«fi II MI KHHSHftHIa H SHI BOH H 111 I 1 I H is 8$$ rnWTWjTfTnfTTrfin Wm HI H 1 I §1 Ml mMMUHS 3 ^i- N- H. THE QUARTERLY JOURNAL GEOLOGICAL SOCIETY OF LONDON. EDITED BY THE ASSISTANT-SECRETARY OF THE GEOLOGICAL SOCIETY. Quod si cui mortalium cordi et curie sit non tantum inventis hserere, atqu« iis uti, sed ad ulteriora penetrare ; atque non disputando adversarium, sed opere naturam vincere ; denique non belle et probabiliter «opinari, sed certo et ostensive scire; tales, tanquatn veri scientiarum filii, nobis ( si videbitur) seadjungant. — Novum Organum, Prcefatio. VOLUME THE SIXTY-THIRD. 1907. LONDON : LONGMANS, GREEN, AND CO. PARIS : CHAELES KLINCKSIECK, 11 RUE DE LILLE. SOLD ALSO AT THE APARTMENTS OF THE SOCIETY. MDCCCCVII. xw?-9/ £tst OF THE OFFICERS OF THE GEOLOGICAL SOCIETY OF LONDON. Elected February 15th, 1907. Sir Archibald Geikie, K.C.B., Sc.D,, D.C.L., LL.D., Sec.E.S. Wic&&xt&iBmt£. John Edward Marr, Sc.D., F.E.S. I Aubrey Strahan, Sc.D., F.E.S. Prof. William Johnson Sollas, Sc.D., I J. J. Harris Teall, M.A., D.Sc, F.R.S. LL.D., F.E.S. I Prof William Whitehead Watts, M.A., I Prof. Edmund Johnstone Garwood, M. A. m!Sc, F.R.S. I dfowtgn §tmux)). C«aslu«r. Sir John Evans, K.C.B., D.O.L., LL.D., I Horace Woollaston Monckton, Treas.L.S. F.E.S., F.S.A.', F.L.S. I Henry Howe Arnold-Bemrose, J.P., M.A. Prof.SainuelHerbertCox.F.C.S.,A.E.S.M. Sir John Evans, K.C.B., D.O.L., LL.D., F.E.S., F.S.A., F.L.S. Prof. Edmund Johnstone Garwood, M.A. Sir Archibald Geikie, K.C.B., Sc.D., D.C.L., LL.D., SecE.S. Wilfrid H. Hudleston, M.A.,F.E.S.,F.L.S. Finlay Loriraer Kitchin, M.A., Ph.D. George William Lamplugh, F.E.S. Prof. Charles Lapworth, M.Sc, LL.D., F R S EichardLydekker, B.A., F.E.S. John Edward Marr, Sc.D., F.E.S. Horace Woollaston Monckton, Treas.L.S. Frederick William Eudler, I.S.O. Prof. William Johnson Sollas,Sc.D.,LL.D., F.E.S. Leonard James Spencer, M.A. Aubrey Strahan, Sc.D., F.E.S. Charles Fox Strangways. J. J. Harris Teall, M.A, D.Sc, F.E.S. Eichard Hill Tiddeman, M.A. Prof. William Whitehead Watts, M.A. M.Sc, F.E.S. Henry Woods, M.A= Arthur Smith Woodward, LL.D., F.E.S. Horace Bolingbroke Woodward, F.E.S. &£Jstetant*i?>e<:retan>, Clerk, Etbrartau, antr Curator L. L. Belinfante, M.Sc. SUstetantsI in Office, Hibrarg, antf ijHuSnnn. W. Eupert Jones. Clyde H. Black. Alec Field. STANDING PUBLICATION COMMITTEE. Sir Archibald Geikie, President. Prof. W. W. Watts. Prof. E. J. Garwood. Prof. S. H. Cox. Dr. F. L. Kitchin. Mr. G. W. Lamplugh. Mr. E. Lydekker. Dr. J. E. Marr. Mr. H. W. Monckton. Secretaries. Prof. W. J. Sollas. Mr. L. J. Spencer. Dr. A. Strahan. Dr. J. J. H. Teall. Mr. H. Woods. Dr. A. Smith Woodward. TABLE OF CONTENTS. Page Andrews, Dr. Charles William. Note on the Cervical Vertebra of a Zeuglodon from the Barton Clay of Barton Cliff (Hamp- shire) 124 Arber, E. A. Newell. On the Upper Carboniferous Rocks of West Devon and North Cornwall 1 Arnold-Bemrose, Henry Howe. The Toadstones of Derbvshire : their Field-Relations and Petrography (Plates XIX-XXII) . . 241 Baldwin- Wiseman, William Ralph. The Influence of Pressure and Porosity on the Motion of Sub-Surface Water (Plate V) . . 80 Bolton, Herbert. On a Marine Fauna in the Basement-Beds of the Bristol Coal-field (Plate XXX) 445 Bonney, Prof. Thomas George. On the Southern Origin attri- buted to the Northern Zone in the Savoy and Swiss Alps .... 294 Buckman, Sydney S. Brachiopod Morphology : Cineta, Eudesia, and the Development of Ribs (Plate XXIV) 338 . On the Correlation of the Bath-Doulting Strata with those of Dorset .'.'..'.. 424 Davies, Dr. Arthur Morley. The Kimeridge Clay and Corallian Rocks of the Neighbourhood of Brill, Buckinghamshire (Plate I) 29 Davison, Dr. Charles. The Swansea Earthquake of June 27th, 1906 (Plate XXV) 351 . The Ochil Earthquakes of September 1900 to April 1907 (Plate XXVI) 362 Douglas, James Archibald. On Changes of Physical Constants which take place in certain Minerals and Igneous Rocks, on the Passage from the Crystalline to the Glassy State ; with a short Note on Eutectic Mixtures 145 «2 IT TABLE OF CONTENTS. Page Evans, Oswald Habdey. Notes on the Raised Beaches of Taltal (Northern Chile) 64 Habmeb, Fbederic William. On the Origin of certain CaSon- like Valleys associated •with Lake-like Areas of Depression (Plates XXXI-XXXV) 470 Haebison, Prof. John Btjrchmobe. The Coral-Rocks of Bar- bados (Plate XXIH) 318 Hinslow, Rev. Prof. George. On the Xerophytic Characters of certain Coal-Plants, and a Suggested Origin of Coal-Beds 282 Hooley, Reginald Waltee. On the Skull and greater Portion of the Skeleton of Goniopholis crassidens from the Wealden Shales of Atherfield, Isle of Wight (Plates II-IV) 50 Jukes-Beowne, Aleeed John. The Age and Origin of the Plateaux around Torquay 106 Lamplugh, Geoege William. The Geology of the Zambezi Basin around the Batoka Gorge, Rhodesia (Plates XXVII) . . 162 Mawson, Joseph, & A. S. Woodwabd. On the Cretaceous Forma- tion of Bahia (Brazil), and on Vertebrate Fossils collected therein (Plates VI-VIII) 128 Oldham, Richabd Dixon. The Constitution of the Interior of the Earth, as revealed by Earthquakes : (Second Communication). Some New Light on the Origin of the Oceans 344 Paekinson, John. The Post-Cretaceous Stratigraphy of Southern Nigeria 308 — . The Geology of the Oban Hills (Southern Nigeria) 313 . The Crystalline Rocks of the Kukuruku Hills (Southern Nigeria) 317 Reynolds, Prof. Sidney Hugh. A Silurian Inlier in the Eastern Mendips (Plate XVIII) 217 Richaedson, Linsdall. The Inferior Oolite and Contiguous De- posits of the Bath-Doulting District (Plates XXVHI & XXIX) 383 . The Inferior Oolite and Contiguous Deposits of the District between the Rissingtons and Burford 437 Stopes, Maeie C. The Flora of the Inferior Oolite of Brora, Sutherland (Plate XXVII) 375 Walkee, the late John Francis, & L. Richaedson. Remarks on the Brachiopoda from the Fullers' Earth 426 Washington, Dr. Heney S. The Titaniferous Basalts of the Western Mediterranean : a Preliminary Notice 69 TABLE OF CONTENTS. Y Page Woodward, Dr. Arthur Smith. On a New Dinosaurian Reptile (Scleromochlus Taylori, gen. et sp. nov.) from the Trias of Lossiemouth, Elgin (Plate IX) 140 f & J, Mawson. On the Cretaceous Formation of Bahia (Brazil), and on Vertebrate Fossils collected therein (Plates VI- VO) 128 PROCEEDINGS. Proceedings of the Meetings i, lxx Annual Report viii Lists of Donors to the Library xiii List of Foreign Members xxiv List of Foreign Correspondents xxv List of Wollaston Medallists xxvi List of Murchison Medallists xxviii List of Lyell Medallists xxx List of Bigsby Medallists xxxii List of Prestwich Medallists xxxii Applications of the Barlow-Jameson Fund xxxiii Awards of the Daniel-Pidgeon Fund xxxiii, lxxvi Financial Report xxxiv Award of the Medals and Proceeds of Funds xli Anniversary Address of the President 1 Special General Meeting lxxiii, lxxvi CORKIGENDA. Page 322, fig. 4 represents an exposure above that shown in fig. 2 on the same page. Page 434, in title of fig. 6, for ' Hudlestonei ' read ' HuMestoni! LIST OF THE FOSSILS DESCRIBED AND FIGURED IN THIS VOLUME. Name of Species. Formation. Locality. Page Serpala convoluta tetragona Spirorbis midfordensis, sp. hot., fig. 7 Aeanthothyris doidtingensis, sp. nov., pi. xxviii, figs. 1 a- lc midfordensis, sp. nov., pi. xxviii, figs. 2 a-2 c Amboccelia aff. TJrii, pi. xxx, figs. 6 a & Qb Aulacothyris Mandelslohi, pi. xxviii, figs. 3a-3c Chonetes cf. hardrensis, pi. xxx, fig. 4 sp., pi. xxx, figs. 1-3 Cineta orbicularis, pi. xxiv, fig.l pernummus, nom. nov., pi. xxiv, fig. 2 Dictyothyris subreticidata . . . Eudesia orbictdaris, pi. xxiv, fig. IS Flabellothyris flabellum, pi. xxiv, fig. 12 Ismenia Munieri, pi. xxiv, fig. 10 Murchisona, pi. xxiv, fig. 9 POLYCH^TA. j Zone of Exogyra virgida f Lower Kime- |_ ridge Clay ... i Inferior Oolite. . Brachiopoda. I }. Fullers' Earth.. I ) I Coal-Measures. \ Fullers' Earth.., J L Coal-Measures. , Fullers' Earth... ] Fullers' Earth., i Inferior Oolite J Bid's Hill, Brill Midford , ( | Farmcombe -{ Quarry j Doulting-Bridge (^ Quarry Ashton Vale ... f Doulting-Bridge 1 Quarry \ Ashton Vale ... Somerset 47 46-47 435 426 427 459 427-28 r -{457 ^ 458-59 339, 343 342 428-29 341, 343 341, 343 341 341 FOSSILS DESCEIBED AND FIGURED. Name of Species. Formation. Locality. Page Beachiopoda {continued). . XXIV, fig. 11 ."-" languid mytiloides Orbiculoidea nitida Orniihella cadornensis, pi. xxviii, figs. 4 a & 4& ornithocephala, pi. xxviii, figs. 5 a &, 5 b Productus concinnus, mut., pi. xxx, figs. 5 a & 5 b Bhynchonella plateia, sp. nov., pi. xxviii, figs. 8 a-8 c Smithi voluta, sp. nov., pi. xxviii, figs. 7a & lb Walkeri, sp. nov., pi. xxviii, figs. 6 a-6 d Terebratula dcncltingensis, sp. nov., pi. xxix, figs. 1 a-\ c... globata, pi. xxix, figs. 4a-4e lenthayensis, sp. nov., pi. xxix, figs. 2a&2b maxillata, pi. xxix, figs. 3a-Sc spharoidalis WhitaJceri, pi. xxiv, figs. 8a&8b Triqonella Fleuriaztsa, pi. xxiv, &6 ! THgonellina pectunculus, gen. nov., pi. xxiv, fig. 7 Zeilleria emarginata quadnfida, pi. xxiv, figs. 4a&46 cf. quadrifida, pi. xxiv, fig. 5 subquadrifida, pi. xxiv, fig. 3 Coal-Measures. Fullers' Earth.. Coal-Measures. V Fullers' Earth. White Jura. Fullers' Earth. Ashton Vale Midford ^Dyrham Ashton Yale /'Farmcombe Quarry . . Somerset Farmcombe Quarry .. Wellow .... Farmcombe Quarry . Whatley Lenthay Whatley ^ Somerset Farmcombe 341 f 456-57 1457 429-30 430 459 431 431 430-31 431-32 432 433-34 432 433 433 341 ! 339-40 1,340, 342 434 339, 343 J 343 [343 Lamellibeanchiata. Astarte, 5 spp. (including A. ovata, A. monsbeliardensis, & A. pulla ?) Cyprina cyreniformis (?) Lima semipunctata (?) ? Mactromya brevis Modiola, sp. nov., pi. xxx, fig. 11 Nucida . Map showing the plateau-areas and their probable former connexion across Torbay 120 Posterior surface of a cervical vertebra of Zeuglodon WanMyni. 125 Xiv PROCESS-BLOCKS A^D OTHER ILLUSTRATIVE FIGURES. Fig. Page Map showing the localities [near Bahia] where Cretaceous fossils were found 129 Outline-restoration of the skeleton of Scleromochlus Taylori ... 141 1. Apparatus used for melting igneous rocks, by means of an electric current 147 2. Curves showing the relation between the specific gravity of crystal and the melting-points of crystal and glass 156 1. Diagrammatic section illustrating the general features of the plateau [Zambezi basin] t 170 2. Sketch-plan showing the loop of the Deka River at the great fault, near the confluence of the Rondulu River 177 3. Sketch -diagram of the fault along the Deka River, about a mile below the railway-bridge, looking north-eastwards 177 4. Section about halfway down in the cleft at the eastern end of the Chasm at the Victoria Falls 188 5. Sketch-plau of the Batoka Gorge at the Tshimamba Cataracts. 189 6. Sketch-plan of the gorge of the Karamba River, from above Kalonga's Cleft to its confluence with the Zambezi 190 7. Profile of the river-bed at the waterfall above Kalonga's Cleft ; 190 8. Bird's-eye view looking up the Karamba Valley, from near Kalonga's Cleft 191 1 . Map of the Silurian inlier in th e Eastern Mendips 220 2. Sunnyhill Quarry, Stoke Lane, looking south-westwards 224 3. Section of Sunnyhill Quarry 225 4. View of part of the new quarry in the coarse ashy con- glomerate, south-east of Moon s Hill, Stoke Lane, showing the subangular character of some of the blocks 228 5. Rough plan of the trenches dug near the Rifle-Butts, Beacon Hill 229 6. Section passing southwards from Beacon Plantation 234 7. Section from Tadhill House to Bottiehead Springs 234 8. Section a quarter of a mile south-west of Tadhill Farm 236 Vertical sections showing the relative positions of the toad- stones in the Carboniferous Limestone and Yoredale Series of Derbyshire 249 1. Section across the Lepontine Alps 296 2. Section in the Chablais Alps 298 process-blocks and other illustrative figures. xv Fig. Page 3. Diagram to scale, showing the strip of sediraentaries in which movement is supposed to be set up by pressure of additional material 300 4. Possible outline of the Alps after the pre-Miocene uplift 300 5. Outline of the Alps after the post-Miocene uplift 300 Sketch-map of Southern Nigeria 310 1. Sketch-map of the Oban Hills [Nigeria] 314 2. Diagrammatic section from Uwet north-eastwards, showing the relations of the igneous rocks 316 1. Section at Conset Point, eastern face 320 2. Conset north-western Point 322 3. Exposure (in the railway-cutting) above that shown in fig. 1... 322 4. Exposure (in the railway-cutting) above that shown in fig. 2... 322 5. Section at My Lady's Hill, at the point marked ' Rock ' on the map, PI. XXIII , 322 6. Prof. J. W. Spencer's section 323 7. Section from Conset Point to My Lady's Hill 323 8. Section at Thicket Hill 323 9. Section at Bushy Park 326 10. Sections in Mapp's Quarry 326 1 1 . Section from Villa Nova to Mount Tabor , 330 12. Sections in Blackman's Gully 330 13. Section at Mount-Wilton Hill 331 Map of the epicentral areas of the Swansea earthquake 354 1. Earthquakes of Sept. 17th and Sept, 22nd, 1900 [map] 363 Earthquake of July 23rd, 1905 [map] 365 o 3. Earthquakes of Oct. 8th, Dec. 28th, and Dec. 30th, 1906 [map] 369 Epidermis-cells of living and fossil Ginkgo 380 1. Diagram, to show the probable relationship of the ' Con- glomerate-Bed ' to the underlying deposits in the neighbour- hood of Doulting 392 2. View in Vallis Vale, showing the Inferior Oolite resting uncon- f ormably upon the Carboniferous Limestone 402 PROCESS-BLOCKS AXD OTHER ILLUSTRATIVE FIGURES. Fig. Page 3. View of quarry in Vallis Yale, showing the Inferior Oolite resting unconformably upon the Carboniferous Limestone... 403 4. Sketch-section showing the relations of the Inferior-Oolite Beds of the Bath-Doulting district to the deposits above and below them 422 5. Ostr ea Knorri, Yoltz 423 6. Araberleya Htcdlestoni, sp. nov 434 7. Spirorbis midfordensis, sp. nov 435 Diagrammatic section from the ' Eed Ash ' or ' Little Vein ' seam to the end of the exploration-branch in the Ashton- Vale Colliery 452 1. View of Bath and the valley of the Avon, from the north-east. 472 2. The entrance to the gorge at Ironbridge, seen from the west... 473 3. Contour-map of the Vale of Pickering and the Malton Gorge. 476 4. Contour-map of the neighbourhood of Harrington Dingle, an overflow -channel near Chirburv 482 Folding Tables. II. Descriptive section in road-cutting, Midford, near Bath, facing 408 III. Descriptive section in trial-shaft at Timsbury Sleight, facing 416 VI. List of fossils from the Inferior Oolite of the Bath-Doulting district, facing 436 TIL List of fossils from the Fullers' Earth of the Bath-Doulting district, facing 436 PROCEEDINGS OF THE GEOLOGICAL SOCIETY OE LONDON. SESSION 1906-1907. November 7th, 1906. Sir Aechieald Geikie, D.C.L., Sc.D., Sec.E.S., President, in the Chair. Arthur E. Andrew, Imperial Institute, South Kensington, S.W. ; Stanislas Napier Bell, Derby (Tasmania) ; Thomas Henry Davies, Queen Margaret Gold-Mines, Bulong (Western Australia) ; Stanley Charles Dunn, Assoc. R.S.M., Sudan Government-Geologist, Khartum (Sudan) ; William Thomas Griffiths, Assoc.E.S.M., Sibpur College, Calcutta ; Isaac Hodges, Whitwood, Normanton ; P. K. Majumdar, M.I.M.E., 45 George Eoad, Edgbaston, Birmingham ; Leonard Edward Beard Pearse, 79 Gordon Eoad, Ealing, W. ; Charles Blades Coverdale Storey, M.A., E.L.S., E.E.G.S., Lancaster, and 24 a Portland Place, W. ; Edward Brough Taylor, M.Inst.C.E., Caxton House, Westminster, S.W. ; and John Eobert Eobinson Wilson, M.Inst.C.E., H.M. Inspector of Mines, 182 Chapeltown Eoad, Leeds, were elected EeJlows of the Society. The List of Donations to the Library was read. The following communications were read : — 1. ' The Upper Carboniferous Eocks of West Devon and North Cornwall.' By E. A. Newell Arber, M.A., E.L.S., E.G.S. 2. ' The Titaniferous Basalts of the Western Mediterranean.' By Dr. Henry S. Washington, For.Corr.Geol.Soc. vol. lxiii. a il PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. I907, The following specimens, photographs, and maps were ex- hibited : — Specimens from the Upper Carboniferous rocks of West Devon and North Cornwall, and lantern-slides, exhibited by E. A. Jewell Arber, M.A., F.L.S., F.G.S., in illustration of his paper. Photographs taken in Japan and at San Francisco, 1906, exhibited and presented by Ivan A. Stigand, B.A., F.G.S. A photograph of a section in Barbados, showing soil formed by volcanic dust (?), resting upon the Coral-Formation of the island, exhibited on behalf of G. Hughes, F.C.S., by the Secretary. Geological Survey of England & Wales : 1-inch Map, n. s., Sheets 110, 123, and 357 *& 360, colour-printed, presented by the Director of H.M. Geological Survey. Geological Commission of the Cape of Good Hope : Geological Map of the Colony, on the scale of 3| miles to the inch — Sheet 1, by A. TV. Eogers, E. H. L. Schwarz, & A. L. Da Toit, presented by the above-mentioned Commission. November 21st, 1906. Sir Archibald Geieie, D.C.L., Sc.D., Sec.E.S.. President, in the Chair. The List of Donations to the Library was read. The following communications were read : — 1. 'The Kimeridge Clay and Corallian Eocks of the Neigbour- hood of Brill (Buckinghamshire).' Bv Arthur Morlev Davies, A.E.C.S., B.Sc, F.G.S. 2. l On the Skull and greater Portion of the Skeleton of Gonio- plioTis crassidens from the Wealden Shales of Atherfield (Isle of Wight).' By Eeginald Walter Hooley, F.G.S. The following specimens, etc. were exhibited : — Jurassic fossils and specimens of selenite, from near Brill (Buck- inghamshire), exhibited by A. M. Davies, A.E.C.S., B.Sc, F.G.S., in illustration of his paper. Skull of Goniopholis crassidens, exhibited by B. W. Hooley, F.G.S.. in illustration of his paper. A photograph of a specimen of Siigmaria, bearing on its fractured surface an impression of Lepidodendron Sternbergii, found in the grounds of the South Yorkshire Asvlum, near Sheffield, exhibited on behalf of Mr. H. W. B. Cotterill. Vol. 63.] PROCEEDINGS 07 TUT. GEOLOGICAL SOCLE1T. December 5th, 1906. Sir Archibald Gelkie, D.C.L., Sc.D., Sec. U.S., President, in the Chair. Capt. Henry Alford, Dalcross Castle (Inverness-shire) ; Stanley Claude Bailey, Assoc. M.Inst. C.E., The Laurels, Banstead Road, Ewell (Surre}T) ; Benjamin Alfred Baker, 11 Westbury Park, Durdham Down, Bristol ; Asok Bose, c/o Messrs. Thomas Cook & Son, London ; Moses Bruines Cotsworth, Acomb, York; Samuel Rennie Haselhurst, B.Sc, Lecturer in Geology & Geography, 14 Edith Street, Tynemouth ; Douglas R. Home, 30 Lexham Gardens, W. ; H. Cecil Jones, Geological Survey of India, Calcutta ; William John Lakeland, Hsipau, Northern Shan States (Upper Burma) ; Frederic Maurice Lavanchy, 30 St. Augustine's Avenue, Croydon ; Guy Pilgrim, B.Sc, Geological Survey of India, Calcutta; William Edmund Francis Powney, Chief Chemist to the Egyptian Govern- ment, c/o G. T. Holloway, 57 Chancery Lane, W.C. ; and Arthur Beeby Thompson, A.M.I.Mech.E., Leadenhall Buildings, Leadenhal] Street, E.C., were elected Fellows of the Society. The List of Donations to the Library was read. The following communications were read : — 1. ' On the Geological Conditions which have contributed to the Success of the Artesian Boring for Water at Lincoln.' By Prof. Edward Hull, M.A., LL.D., F.R.S., F.G.S. 2. ' Notes on the Raised Beaches of Taltal (Northern Chile).' By Oswald Hardey Evans, F.G.S. The following specimens, etc. were exhibited : — Specimens from the Lincoln boring, exhibited by Percy Griffith, M.Inst.C.E., F.G.S., in illustration of Prof. E. Hull's paper. Specimens and drawings, exhibited by 0. H. Evans, F.G.S., in illustration of his paper. International Geological Congress Map of North America, and lantern-slides illustrative of the Excursions of the International Geological Congress, Mexico, 1906, exhibited by Maurice M. Allorge, Lie. es Sc, F.G.S. PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. I907. December 19th, 1906. Sir Aechlbald Gelkte, D.C.L., Sc.D., Sec.E.S., President, in the Chair. Hansaburo Hunter, Assoc.E.S.M., 24 & 25 Fenchurch Street, E.C., and 29 Kobe (Japan) ; Lawrence G. Hutchison, Assoc.E.S.M., P.O. Box 371, Auckland (New Zealand) ; George Blundell Long- staff, M.A., M.D., Highlands, Putney Heath, S.W., and Twitchen, Mortehoe, E.S.O. (North Devon); Murray Stuart, Yesta House, Lodge Eoad, Birmingham ; and Ivor Thomas, B.Sc, Ph.D., Assistant- Palaeontologist to the Geological Survey, Museum, Jermyn Street, S.~W., and Glanamman (Caermarthenshire), were elected Fellows ; Count Hermann zu Solms-Laubach, Professor of Botany in the University of Strasburg (Alsace), was elected a Foreign Member ; and Prof. William Morris Davis, Harvard University, Cambridge (Mass.), U.S.A., was elected a Foreign Correspondent of the Society. The List of Donations to the Library was read. The following communications were read : — 1. ' The Post-Cretaceous Stratigraphy of Southern Nigeria.' By John Parkinson, B.A., F.G.S. 2. ' The Geology of the Oban Hills (Southern Nigeria).' By John Parkinson, B.A., F.G.S. 3. 'The Crystalline Eocks of the Kukuruku Hills (Central Province of Southern Nigeria).' By John Parkinson, B.A., F.G.S. The following specimens and maps were exhibited : — Eock-specimens and microscope-sections from Southern Nigeria, exhibited by John Parkinson, B.A., F.G.S., in illustration of his papers. General Geological Map of Eumania, Sheets 28, 29, & 34, uTm' 1906, presented by Dr. G. Stefanescu, Director of the Geolo- gical Survey of that kingdom. Tol. 63.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. V January 9th, 1907. Sir Archibald Geikie, D.C.L., Sc.D., Sec.R.S., President, in the Chair. Capt. Francis Ivan Leslie Ditmas, M.I.M.E., United Forces 'Club, 117 Piccadilly, W. ; Frederick Alldis Eastaugh, Forty Hill, Enfield; John Jervis Garrard, Mutual Buildings, Smith Street, Durban (Natal) ; and John Hilder Woodhead, 3 College Mansions, Winchester Avenue, Brondesbury, jST.W., were elected Fellows of the Society. The following Fellows, nominated by the Council, were elected Auditors of the Society's Accounts for the preceding year : — •Charles Fox Strang ways and Capt. Arthur W. Stiffe. The List of Donations to the Library was read. The following communications were read : — 1. ' On the Cretaceous Formation of Bahia (Brazil) and on the Vertebrate Fossils contained therein.' By Joseph Mawson, F.G.S., and Arthur Smith Woodward, LL.D., F.R.S., F.L.S., F.G.S. 2. ' On a New Dinosaurian Reptile from the Trias of Lossie- mouth. Elgin/* By Arthur Smith Woodward, LL.D., F.R.S.. F.L.S., F.G.S. The following specimens were exhibited : — Lower Cretaceous fossils from Bahia (Brazil), collected by Joseph Mawson, F.G.S., exhibited by him and by A. Smith Woodward, IjL.D., F.R.S., F.L.S., F.G.S., in illustration of their paper. Upper Cretaceous vertebrate fossils from Northern Brazil, and a specimen of Stereosternum tumidum from the Permo-Carboniferous of Sao Paulo (Brazil), exhibited by A. Smith Woodward, LL.D., F.R.S., F.L.S., F.G.S. A new Leptolepid fish from the Wealden of Southwater, Hors- ham (Sussex), exhibited by A. Smith Woodward, LL.D., F.R.S., F.L.S., F.G.S. Two specimens of a new Dinosaurian reptile, obtained by Mr. William Taylor, from the Trias of Lossiemouth, Elgin, ex- hibited by A. Smith WToodward, LL.D., F.R.S., F.L.S., F.G.S., in illustration of his paper. VOL. LXIII. vi PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [May I907,. January 23rd, 1907. Sir Archibald Geieie, D.C.L., Sc.D., Sec.E.S., President, in the Chair. The List of Donations to the Library was read. The following communication was read : — ' On the Geolog3T of the Zambezi Basin around the Batoka Gorge (Rhodesia).' By George William Lamplugh, F.R.S., F.G.S. With Petrographical STotes by Herbert Henry Thomas, M.A., B.Sc.r F.G.S. The following specimens, maps, etc. were exhibited : — Specimens from the Zambezi Basin around the Batoka Gorge (Ehodesia), together with photographs and lantern-slides, exhibited by G. W. Lamplugh, F.R.S., F.G.S., in illustration of his paper. " Lantern-slides, exhibited by H. H. Thomas, M.A., B.Sc, F.G.S., in illustration of the petrographical notes accompanying Mr. Lamplugh's paper. Fossils from Mombasa and the neighbouring mainland, exhibited by M. E. Frames, F.G.S., G. W. Lamplugh, F.R.S., F.G.S., and H. B. Muff, B.A., F.G.S. The following specimens found in the 'Roberts Victor ' diamond- mine, about 20 miles east of Boshof (Orange River Colony), were exhibited by E. H. V. Melvill, F.G.S., namely : — I. Oxidized kimber- lite, locally known as ' yellow ground.' II. ' Cyanite-garnet-rock.r It is the only specimen, a portion of a small rounded boulder, found in the mine ; but smaller pebbles are occasionally found. An extract from a letter received from Prof. Dr. R. Beck, of Freiberg, describing the specimen,, is printed in the Transactions of the Geological Society of South Africa, 1906. III. Garnet-rock found in the same mine ; the boulders are plentiful, and measure occasionally 2 feet in diameter. Thirty-five quarter-sheets of the 6-inch Geological Survey-map of Staffordshire, surveyed by G. Barrow, W. Gibson, T. I. Pocock, & C. B. Wedd, 2nd editions, presented by the Director of H.M. Geological Survey. February 6th, 1907. J. E. Marr, Sc.D., F.R.S., Vice-President, in the Chair. James Stanley Diggle, The Hollies, Heywood (Lancashire) ; George Allan Frost, 16 Homesdale Road, Bromley (Kent); Richard Samuel Johnson, Public Works Department, Cradock (Cape Colony) ; Ezra Masillamani, B.A., B.Sc, A.R.C.S., Geologist to the Travancore Government, Trivandrum (Southern India); William Dicks Shuard, Yol. 63.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. VU B.Sc, L.C.P., Mackenzie Park, Slough; Gavin Hildick Smith, Thornleigh, Lichfield Road, Walsall ; Bernard Smith, B.A., Geological Survey, 28 Jermyn Street, S.W. ; and Samuel Shepheard Stanley, Pair View House, Harbury, Leamington, were elected Pellows of the Society. The List of Donations to the Library was read : — The following communications were read : — 1. ' Note on the Cervical Vertebra of Zeuglodon from the Barton Clay of Barton Cliff (Hampshire).' By Charles William Andrews, B.A., D.Sa, P.R.S., F.G.S. 2. ' The Origin and Age of the Plateaus around Torquay.'" By Alfred John Jukes-Browne, B.A., P.G.S. The following specimens and maps were exhibited : — A cervical vertebra of Zeuglodon Wanklyni from Barton Cliff, exhibited by Dr. C. W. Andrews, B. A., F.ft.S., P.G.S., in illustration of his paper. Specimens of vertebras of Prozeuglodon atrox, from the Middle Eocene of Egypt, exhibited by Dr. C. W. Andrews, B.A., F.R.S., P.G.S. Geological Survey of England and Wales : Geological Map, 1 inch = 1 mile, n.s., Sheet 341, West Pleet (Dorset) Drift, by A. Strahan (colour-printed, 1907) ; and Index Map, 1 inch = 4 miles, Sheets 8 & 12, Drift (colour-printed, 1907), presented by the Director of H.M. Geological Survey. 62 ANNUAL GENERAL MEETING, February 15th, 1907. Sir Archibald G-eikie, D.C.L., LL.D., Sc.D., Sec.R.S., President, in the Chair. Eeport of the Council foe 1906. The generally-flourishing condition of the Society was marked in the past year by a welcome increase in the Xumber of Fellows. In 1906 the Fellows elected numbered 51 (as compared with 48 in 1905), and 38 of these paid their Admission-Fees before the end of the year. Moreover, 12 Fellows who had been elected in the previous year paid their Admission-Fees in 1906, making the total Accession of new Fellows within the twelve months under review amount to 50. Setting against this number a loss of 38 Fellows (27 by death, 7 by resignation, and 4 by removal from the List, under Bye-Laws, Sect. VI, Art. 5), it will be noted that there is an increase in the dumber of Fellows of 12 (as compared with a decrease of 12 in 1905, and of 3 in 1904). The total dumber of Fellows is thus increased to 1251, made up as follows : — Compounders, 273 (7 less than in 1905) ; Con- tributing Fellows, 946 (20 more than in 1905, and 12 more than in 1904) ; and Xon-Contributing Fellows, 32 (1 less $han in 1905). Turning now to the Lists of Foreign Members and Foreign Correspondents, we have to deplore the loss, through an unfor- tunate lift-accident, of 1 Foreign Member, the venerable Prof. Eugene Eenevier ; and also the loss of 1 Foreign Correspondent, Prof. S. L. Penfield. Moreover, at the end of 1905, there had remained two vacancies in the List of Foreign Correspondents. These vacancies were, in part, filled by the transfer of Count Hermann zu Solms-Laubach from the List of Foreign Correspondents to that of Foreign Members ; and by the election of Prof. J. M. Clarke, Prof. W. M. Davis, and Dr. J. J. Sederholm as Foreign Cor- respondents. At the end of 1906 there was still one vacancy in the List of Foreign Correspondents. With regard to the Income and Expenditure of the Society during Vol. 6$.'] AMSUAL REPORT. ix the year 1906, the figures set forth in detail in the Balance-Sheet may be summarized as follows : — The actual Eeceipts, excluding the Balance of .£305 2s. 9d. brought forward from the previous year, amounted to .£2943 18s. 6d., being £82 9s. 6d. less than the estimated Income. On the other hand, the total Expenditure during the same period amounted to £3032 19s. Sd., being ,£141 18s. 4cZ. less than the estimated Expenditure for the year, and £89 Is. 2d. in excess of the actual Receipts, the year closing with a Balance in hand of .£216 Is. 7d. The principal item in regard to wThich the Expen- diture exceeded the sum provided in the Estimates was that of Miscellaneous Printing (excess <£20 19s. lid.). On the other hand, no Expenditure was incurred in respect of Ventilation (for which £90 0s. Od. had been allowed) or in respect of the History of the Geological Society (for which £50 0s. Od. had been allowed). Mr. H. B. Woodward has completed the 'History,' and is now engaged in passing it through the press. The illustrations are being prepared under the supervision of Prof. E. J. Garwood, and Mr. E. S. Hemes has undertaken the section connected with the Charter and the Bye-Laws. A Committee has been appointed to make the necessary arrange- ments in connexion with the forthcoming celebration of the Centenary of the foundation of this Society. The celebration is to take place in the latter days of September, and it is hoped that there will be a numerous attendance of Delegates from kindred institutions in this county and abroad. The Council have to announce the completion of Yol. LXII and the commencement of Yol. LXIII of the Society's Quarterly Journal. Full particulars in regard to Mr. C. Davies Sherborn's admirably- compiled Card- Catalogue of the Library are set forth in the appended Report from the Library-and-Museum Committee. The fourth Award from the Daniel -Pidgeon Trust-Fund was made, on May 9th, 1906, to Miss Helen Drew, Newnham College, Cambridge, who proposed to examine the relationship of the Caradoc and Llandovery rocks in South Wales, between the Llandeilo and Fishguard districts. The following Awards of Medals and Funds have also been made by the Council : — The Wollaston Medal is awarded to Prof. William Johnson Sollas, F.B..S., in recognition of the value of his 'researches concerning the mineral structure of the Earth,' and particularly of his valuable contributions to the sciences of Petrology and Palaeontology. The Murchison Medal, together with a Sum of Ten Guineas from the Murchison Geological Fund, is awarded to Mr. Alfred Harker, F.R.S., in recognition of his valuable contributions to Geological Science by means of his Penological Memoirs, especially those relating to the Isle of Skye. The Lyell Medal, together with a Sum of Twenty-Five Pounds from the Lyell Geological Fund, is awarded to Dr. Joseph X PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1907, Frederick Whiteaves, ' as a mark of honorary distinction, and as an expression on the part of the Council that he has deserved well of the Science,' by his prolonged researches on the Geology and Palae- ontology of Canada. The Bigsby Medal is awarded to Mr. Arthur William Rogers, M.A., as an acknowledgment of his eminent services to Geology, especially in relation to the Geological Survey of Cape Colony. The Balance of the Proceeds of the Wollaston Donation-Fund is awarded to Dr. Arthur Vaughan, B.A., as an acknowledgment of the value of his investigations into the Zonal Sequence of the Lower Carboniferous Rocks, and to encourage him in further research. The Balance of the Proceeds of the Murchison Geological Fund is awarded to Dr. Felix Oswald, as an acknowledgment of his investigations into the Geology of Armenia, and of his exertions in overcoming the difficulties which he encountered in the publication of his results. A moiety of the Balance of the Proceeds of the Lyell Geological Fund is awarded to Mr. Thomas Crosbee Cantrill, B.Sc, in recognition of the value of his contributions to our knowledge of the Palaeozoic Pocks of Wales and the Forest of Wyre, and to encourage him in further research. The other moiety of the Balance of the Proceeds of the Lyell Geological Fund is awarded to Mr. Thomas Sheppard, F.G.S., as an acknowledgment of the excellent work accomplished by him on the Geology of Eastern Yorkshire, and as an encouragement to further research. RePOKT OE THE LlBEAEY-AlSrD-MuSEUM COMMITTEE EOR 1906. The Committee have pleasure in reporting that the Additions made to the Library during the year under review have maintained, both in number and in importance, the standard of previous years. During the past twelve months the Library has received by donation 239 Volumes of separately-published Works, 309 Pamphlets and detached Parts of Works, 289 Volumes and 70 detached Parts of Serial Publications, and 24 Volumes of Newspapers. The total Number of Accessions to the Library by Donation is thus found to amount to 552 Volumes, 309 Pamphlets, and SO detached Parts. Moreover, 52 Sheets of Geological Maps were presented to the Library, including 28 Folios of the ' Geologic Atlas of* the United States ' ; 9 Sheets received from the Geological Survey of Sweden ; 6 Sheets from the Geological Survey of England & Wales (one being a general geological map of the British Isles) ; 3 Sheets from the Geological Survey of Rumania ; and 2 from that of Japan. Messrs. J. B. Harrison & C. W. Anderson presented their geological map of parts of the Essequibo and Cuyuni Rivers (British Guiana) ; and single-sheet Maps were received from the Vol. 6$.~] ANNUAL EEPOKT. X ■Geological Surveys of Scotland, the Cape Colony, the Transvaal Colony, Queensland, and Alabama. Among the Books and Pamphlets mentioned in the foregoing- paragraph, especial attention may" be directed to the following ■works: — Vol. II of Miss Hertha Sollas's translation of Suess's ' Face of the Earth ' ; the second and final volume of the monograph on the Rocks of Cape-Colville Peninsula (N.Z.), by Prof. W. J. Sollas & Dr. A. McKay ; the new edition of Sir Boverton Redwood's great monograph on ' Petroleum & its Products ' ; Capt. H. G. Lyons's ' Physiography of the^River Nile' ; Dr. R. D. M. Verbeek's * Description geologique de file d'Ambon ' ; ohe 5th edition of Prof. G. A. J. Cole's ' Aids to Practical Geology ' ; Mr. J". H. Sears's monograph on the Physiography, Geology, etc. of Essex County (Mass.) ; M. L. Cayeux's ' Structure & Origine des Gres du Tertiaire parisien ' ; the second edition of Sir Archibald Geikie's ' Pounders of Geology ' ; the Scientific Reports of the French Government Expedition to the Sahara ; the Geological Report on the Country traversed by the South Australian Government's prospecting Expedition to the North-West Territory ; Dr. C. W. Andrews's Catalogue of the Tertiary Vertebrata of the Fayum in the Natural History Museum ; Mr. E. A. Newell Arber's Catalogue of the Glossopteris-Flora in the same Museum ; the geology of the following counties, forming part of the Victoria History of the Counties of England : Bedfordshire, Berkshire, Derbyshire, Devon, Durham, Somerset, and Warwickshire; the Geological Survey- Memoirs on the Scilly Isles, Sidmouth & Lyme Regis, Stoke-upon- Trent, Macclesfield & Congleton, and Mid- Argyll ; the Memoirs on the Water-Supply of Suffolk and that of the East Riding of York- shire ; Dr. A. Strahan's ' Guide to the Geological Model of the Isle of Purbeck ' ; and the 2nd edition of Mr. H. B. Woodward's Memoir on ' Soils & Sub-Soils of London & its Neighbourhood/ Moreover many valuable publications, too numerous to particularize in this place, were received from the Geological Surveys and other Government Departments of the Cape Colony, the Transvaal Colony, Natal, the various States of the Commonwealth of Australia, New Zealand, Mysore, British Guiana, Newfoundland, New Jersey, Iowa, Ohio, the United States, Finland, Russia, etc., and from the New York State Museum, the Bergen Museum, and the Indian Museum, Calcutta. The Books and Maps, enumerated above, were the gift of 169 Personal Donors ; 129 Government Departments and other Public Bodies ; and 175 Societies and Editors of Periodicals. The Purchases, made on the recommendation of the standing Library Committee, included 37 Volumes and 9 detached Parts of separately-published Works ; 40 Volumes and 9 Parts of Works published serially ; and 15 Sheets of Maps. In consequence of certain suggestions, made by Dr. F. A. Bather, for improvement in the method of binding books in the Society's Library, a ' Binding Sub-Committee ' was appointed on March 8th, 1905 ; and, after considering the very carefully-compiled statistics Xii PKOCEEDIXGS OF THE GEOLOGICAL SOCIETY. [Ma}' I907,. and other data brought before them by Dr. Bather, the Sub- Committee recommended that the use of calf be discontinued, and that it be replaced in part by pigskin, mountain sheepskin, and other leathers, and in part by better classes of cloth than those hitherto used, the binders being required to pledge themselves to strict compliance with the regulations in the matter of binding prescribed by the Society of Arts. The necessary specifications were drawn up by Dr. Bather, and a great improvement is now discernible in the bindings in the Library, — the total expenditure involved re- maining apparently much the same as before the adoption of more durable forms of binding. The Committee are of opinion that the Society is deeply indebted to Dr. Bather for his strenuous exertions in this matter. The Expenditure incurred in connexion with the Library during the year 1906 was as follows : — £ s. d. Books, Periodicals, etc. purchased 63 11 0 Binding of Books and Mounting of Maps. . . . 146 18 5 =£210 9 5 The Card-Catalogue of the Library, begun in 1901, has now, thanks to the unremitting labour devoted to it by Mr. C. D. Sherborn, been brought into a sufficiently-forward state to be of general use to the Fellows. It comprises the whole of the 1881 Catalogue, the 'separata' listed annually since that date, and all the entries in ' Geological Literature ' from 1894 to the end of 1905. As soon as the editing of the existing material is complete (a task which will reduce some 140,000 cards to about 80,000, and so allow room for the annual accessions for some years to come), an attempt will be made to extract the geological material from the Periodical and Academical literature of the past. The Catalogue is, therefore, practically complete from 1894, it contains a large number of Entries relating to earlier years, and will gradually become more and more complete. Museum. For the purpose of study and comparison, the Society's Collections were visited on 27 occasions during the year, the contents of about 84 drawers being thus examined. The permission of the Council having been duly obtained, about 43 specimeus were lent during 1906 to various investigators. ISTo expenditure has been incurred in connexion with the Museum during the past year. Vol. 63.] ANNUAL REPORT. Xlii The appended Lists contain the Names of Government Depart- ments, Public Bodies, Societies, Editors, and Personal Donors, from whom Donations to the Library have been received during the year under review : — I. Government Departments and other Pitblic Bodies. Alabama. — Geological Survey, Montgomery (Ala.). American Museum of Natural History. New York. Argentina. — Ministerio de Agricultura, Buenos Aires. Australia (S.). See South Australia, etc. Austria. — Kaiserlich-Konigliche Geologische Keichsanstalt. Vienna. Bavaria. — Konigliches Bayerisches Oberbergamt. Munich. Belgium. — Academie Boyale des Sciences, des Lettres & Beaux- Arts de Belgique. Brussels. . Musee Royal d'Histoire Naturelle. Brussels. Bergen. — Bergens Museum. Berlin. — Konigliche Preussiscbe Akademie der Wissenschaften. Birmingham, University of. Bohemia. — Naturwissenschaftliche Laudesdurchforschung. Prague. . Royal Museum of Natural History. Prague. Bristol. — Public Library. British Columbia.— Department of Mines, Victoria (B.C.). British Guiana.— Department of Mines, Georgetown. British South Africa Company. London. Buenos Aires. — Museo Naeional de Buenos Aires. California, University of. Berkelejr (Cal.). Cambridge (Mass.). — Museum of Comparative Zoology, Harvard College. Canada. — Geological & Natural History Survey. Ottawa. , High Commissioner for. London. Cape Colony. — Department of Agriculture : Geological Commission. Cape Town. . South African Museum. Cape Town. Chicago. — 'Field' Columbian Museum. C6rdoba (Argentine Republic). — Academia Nacional de Ciencias. Cracow. — Academie des Sciences. (Akademie Umiejetnosci.) Denmark.— Commission for Ledelsen af de Geologiske og Geograpbiske Underso- gelser i Gronland. Copenhagen. . Kongelige Danske Videnskabernes Selskab. Copenhagen. Dublin. — Royal Irish Academy. Egypt. — Department of Public Works : Geological Survey. Cairo. Finland. — Finlands Geologiska Undersokning. Helsingfors. France. — Ministere des Travaux Publics. Paris. . Museum d'Histoire Naturelle. Paris. Germany. — Kaiserlicke Leopoldinisch-Carolinische Deutsche Akademie der Naturforscher. Halle an der Saale. Great Britain. — Army Medical Department. London. . British Museum (Natural History). London. . Colonial Office. London. ■ . Geological Survey. London. . Home Office. London. . India Office. London. Holland. — Departement van Kolonien. The Hague. Hull. — Municipal Museum. Hungary. — Konigliche Ungarische Geologische Anstalt (Magyar Foldtani Tarsulat). Budapest. India. — Geological Survey. Calcutta. . Indian Museum. Calcutta. . Surveyor-General's Office. Calcutta. Iowa Geological Survey. Des Moines (Iowa). Ireland. — Department of Agriculture & Technical Instruction. Dublin. Italy. — Reale Comitato Geologico. Rome. Japan. — Earthquake-Investigation Committee. Tokio. . Geological Survey. Tokio. PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [May 1907, Jassy, University of. Kansas. — University Geological Surve}-. Lawrence (Kan.). Kingston (Canada). — Qneen's College. London. — City of London College. . Imperial Institute. . Royal College of Surgeons. . University College. Magdeburg. — Museum fur Natur- und Heimatkunde. Melbourne (Victoria). — National Museum. Mexico. — Institute Geologico. Mexico City. Michigan College of Mines. Houghton (Mich.). Milan. — Reale Istituto Lombardo di Scienze & Lettere. Missouri. — Bureau of Geology & Mines. Jefferson City (Mo.). Montana University. Missoula (Mont.). Munich. — Konigliche Bayerische Akademie der Wissenschaften. Mysore Geological Department. Bangalore. Nancy. — Academie de Stanislas. Naples. — Accademia delle Scienze. Natal. — Department of Mines. Pietermaritzburg. . Geological Survey. Pietermaritzburg. . Government Museum. Pietermaritzburg. Newcastle-upon-Tyne. — Armstrong College. New Jersey. — Geological Survey. Trent-ham (N.J.). New South Wales, Agent-General for. London. . Department of Mines & Agriculture. Sydney (N.S.W.). . Geological Survey. Sydney (N.S.W.). New York State Museum. Albany (N.Y.). New Zealand. — Department of Mines. Wellington (N.Z.). . Geological Survey. Wellington (N.Z.). Norway. — Geological Survey. Christiania. Nova Scotia. — Department of Mines. Halifax (N.S.). Ohio Geological Survey. Columbus (Ohio). Padua. — Reale Accademia di Scienze, Lettere & Arti. Paris. — Academie des Sciences. Perak Government. Taiping. Peru. — Ministerio de Fomeuto. Lima. Pisa, Royal University of. Portugal. — Commissao dos Trabalhos geologicos. Lisbon. Prussia. — Ministerium fur Handel & Gewerbe. Berlin. . Konigliche Preussische Geologische Landesanstalt. Berlin. Queensland, Agent-General for. London. . Department of Mines. Brisbane. . Geological Survey. Brisbane. Redruth School of Mines. Rhodesia. — Chamber of Mines. Bulawayo. Rhodesian Museum. Bulawayo. Rio de Janeiro. — Museu Nacional. Rome. — Reale Accademia dei Lincei. Russia. — Comite Geologique. St. Petersburg. . Section Geologique du Cabinet de S.M. l'Empereur. St. Petersburg. South Australia, A gent- General for. London. -. Geological Survey. Adelaide. Spain. — Comision del Mapa Geol6gico. Madrid. Stockholm. — Kongliga Svenska Vetenskaps Akademi. Sweden. — Sveriges Geologiska Undersokning. Stockholm. Switzerland. — Geologische Kommission der Schweiz. Berne. Tasmania.— Secretary for Mines. Hobart. Tokio. — Imperial University. . College of Science. Transvaal. — Geological Survey. Pretoria. ■ -■ Mines Department. Pretoria. Turin. — Reale Accademia delle Scienze. United States.— Department of Agriculture. Washington (D.C.). . Geological Survey. Washington (D.C.). . National Museum. Washington (D.C.). Upsala, University of. Vol. S^.'] ANNUAL REPORT. Victoria (Austral.). Agent-General for. London. ( ). Department of Mines. Melbourne. ( ). Geological Survey. Melbourne. Vienna. — Kaiserliche Akademie der Wissenschaffcen. Washington (D.C.).— Smithsonian Institution. ■ Territory (U.S.A.). — Geological Survey. Olympia (Wash.). West Indies. — Imperial Agricultural Department. Bridgetown (Barbados). Western Australia, Agent-General for. London. . Department of Mines. Perth (W.A.). . Geological Survey. Perth (W.A.). Wisconsin. — Geological & Natural History Survey. Madison (Wise). II. Societies and Editors. Acireale. — Accademia di Scienze, Lettere & Arti. Adelaide. — Royal Society of South Australia. Agram. — Societas Historico-Naturalis Croatica. Alnwick. — Berwickshire Naturalists' Club. Basel. — Naturforschende Gesellschaft. Bath.— Natural History & Antiquarian Field-Club. Belgrade. — Servian Geological Societ}'. Berlin. — Deutsche Geologische Gesellschaft. . Gesellschaft Naturforschender Freunde. . ' Zeitschrift for Praktische Geologic' Berne. — Schweizerische Naturforschende Gesellschaft. Bishop Auckland. — Wearside Naturalists' Field-Club. Bombay Branch of the Royal Asiatic Society. Bordeaux. — Societe Linneenne. Boston (Mass.). — American Academy of Arts & Sciences. . Boston Society of Natural History. Bristol Naturalists' Society. Brooklyn (N. Y.) Institute of Arts & Sciences. Brunswick. — Verein fur Naturwissenschaft zu Braunschweig. Brussels. — Societe beige de Geologie, de Paleontologie & d'Hydrologie. Budapest. — Foldtani Kozlony. Buenos Aires. — Sociedad Cientifica Argentina. Bulawayo. — Rhodesian Scientific Association. Caen. — Societe Linneenne de Normandie. Calcutta. — Asiatic Society of Bengal. . ' Indian Engineering.' Cambridge Philosophical Society. Cape Town. — South African Association for the Advancement of Science. . South African Philosophical Society. Cardiff. — South Wales Institute of Engineers. Chambeiy. — Societe d'Histoire Naturelle de Savoie. Chicago. — ' Journal of Geology.' Christiania. — Norsk Geologisk Forening. . ' Nyt Magazin for Naturvidenskaberne.' Colombo. — Ceylon Branch of the Royal Asiatic Society. Colorado Springs. — ' Colorado College Studies.' Croydon Natural History & Scientific Society. Denver. — Colorado Scientific Society. Dijon. — Academie des Sciences, Arts & Belles Lettres. Dorpat (Jurjew). — Naturforschende Gesellschaft. Dresden. — Naturwissenschaftliche Gesellschaft. ■. Verein fur Erdkunde. Edinburgh Geological Society. . Royal Scottish Geographical Society. . Royal Society. Ekaterinburg. — Societe Ouralienue d' Amateurs des Sciences Naturelles. Falmouth. — Royal Cornwall Polytechnic Society. Frankfurt am Main. — Senckenbersische Naturforschende Gesellschaft. xv PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May I907,. Freiburg im Breisgau. — Naturforschende Gesellschaft. Geneva. — Societe de Physique & d'Histoire Naturelle. Giessen. — Oberhessisclie Gesellscliaft far Natur- & Heilkunde. Glasgow. — Geological Society. Gloucester. — Cotteswold Naturalists' Field-Club. Gratz. — Naturwissenschaftlicher Verein fur Steiermark. Haarlem. — Societe Hollandaise des Sciences. Halifax (N.S.). — Nova Scotian Institute of Science. Hamilton (Canada) Scientific Association. Hanau. — AVetterauische Gesellschaft fur Gesammte Naturkunde. Havre. — Societe Geologique de Normandie. Helsingfors. — Societe geographique de Finlande. Hereford. — Woolbope Naturalists' Field-Club. Hermannstadt. — Siebenbiirgischer Verein fur Naturwissenschaft. Hertford. — Hertfordshire Natural History Society. Hull Geological Society. Indianapolis (Ind.). — Indiana Academy of Science. Johannesburg. — Geological Society of South Africa. Kiev. — Societe des Naturalistes. Lancaster (Pa.).- — -; Economic Geology.' Lausanne. — Societe Vaudoise des Sciences Naturelles. Lawrence (Kan.). — ' Kansas University Bulletin.' Leeds Geological Association. . Philosophical & Literary Society. . Yorkshire Geological & Polytechnic Society. Leicester Literary & Philosophical Society. Leipzig. — ' Zeitschrift fur Krystallographie & Mineralogie.' Liege. — Societe Geologique de Belgique. . Societe Royale des Sciences. Lille. — Societe Geologique du Nord. Lima. — 'Revista de Ciencias.' Lisbon. — Sociedade de Geographia. Liverpool Geological Society. 3 . Literary & Philosophical Society. London. — ' The Athenaeum.' . British Association for the Advancement of Science. . British Association of Waterworks Engineers (now The Association of Water-Engineers). Chemical Society. ' The Chemical News.' ' The Colliery Guardian.' ' The Geological Magazine.' Geologists' Association. Institution of Civil Engineers. Institution of Mining & Metallurgy. Iron & Steel Institute. Linnean Society. 'The London., Edinburgh. & Dublin Philosophical Magazine.' Mineralogical Society. ' The Mining Journal.' ' Nature.' Palaeontographical Societv. ' The Quarry.' Ray Society. ' Records of the London & West-Country Chamber of Mines.' Royal Agricultural Society. Ro3Tal Geographical Society. Royal Institution. Royal Meteorological Society. Royal Microscopical Society. Royal Photographic Society. Royal Society. Society of Arts. Society of Biblical Archaeology. 'The South-Eastern Naturalist' (S.E. Union of Scientific Societies). Victoria Institute. ' Water.' Zoological Societv. Vol. 63^ ANNUAL REPORT. Xvii Manchester Geological & Mining- Society. . Literary & Philosophical Society. Melbourne (Victoria). — Australasian Institute of Mining Engineers. . Royal Society of Victoria. . 'The Victorian Naturalist.' Mexico. — Sociedad Cientifica ' Antonio Alzate.' Moscow. — Societe Imperiale des Naturalistes. New Haven (Conn.). — ' The American Journal of Science.' New York. — Academy of Sciences. . American Institute of Mining Engineers. . ' Science.' Newcastle-upon-Tyne. — Institution of Mining Engineers. . North-of- England Institute of Mining & Mechanical Engineers. ■. University of Durham Philosophical Society. Northampton. — Northamptonshire Natural History Society. Nurnberg. — Naturhistorische Gesellschaft. Oporto. — Academia poly teen ica. [Coimbra.] ■Ottawa. — Royal Society of Canada. Paris. — Commission Praneaise des Glaciers. . Societe Francaise de Mineralogie. . Societe Geologique de France. . ' Spelunca.' Penzance. — Royal Geological Society of Cornwall. Perth. — Perthshire Society of Natural Science. Philadelphia. — Academy of Natural Sciences. . American Philosophical Society. Pisa. — Societa Toscana di Scienze Naturali. Plymouth. — Devonshire Association for the Advancement of Science. Rennes. — Societe Scientifique & Medicale de l'Ouest. Rochester (N.Y.). — Academy of Science. . Geological Society of America. Rome. — Societa Geologica Italiana. Rugby School Natural History Society. •Santiago de Chile. — Sociedad Nacional de Mineria. . Societe Scientifique du Chili. Sao Paulo. — Sociedade Scientifica. •Scranton (Pa.). — 'Mines & Minerals.' St. John (N.B.). — Natural History Society of New Brunswick. St. Petersburg. — Russische Kaiserliche Mineralogische Gesellschaft. Stockholm. — Geologiska Forening. Stratford. — Essex Field-Club. -Stuttgart. — ' Centralblatt fur Mineralogie, Geologie & Palaontologie.' . ' Neues Jahrbuch fur Mineralogie, Geologie & Palaontologie.' . Oberrheinischer Geologischer Vereiu. . Verein fur Vaterlandische Naturkunde in Wiirttemberg. . ' Zeitschrift fur Naturwissenschaften.' Sydney (N.S.W.). — Linnean Society of New South Wales. -. Rojral Society of New South Wales. Toronto. — Canadian Institute. Toulouse. — Societe d'Histoire Naturelle. Truro. — Rotyal Institution of Cornwall. Vienna. — 'Beitrage zur Palaontologie & Geologie ffisterreich-Ungarns & des Orients.' . ' Berg- & Huttenmanniscb.es Jahrbuch.' . Kaiserlich-Konigliche Zoologisch-Botanische Gesellschaft. Washington (D.C.).— Acadeury of Sciences. . Biological Society. . Philosophical Society. Wellington (N.Z.). — New Zealand Institute. Wiesbaden. — Nassauischer Verein far Naturkunde. York. — Yorkshire Philosophical Society. PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [May 1907, III. Personal Donors. Aineghino, F. Ami, H. M. Anderson, C. W. Andersson, J. G. Arber, E. A. N. Arnold-Bemrdse, H. H. Arsandaux, H. Avebury, Lord. Balcb, H. E. Baldwin, W. Baldwin-Wiseman , W .E . Bandelier, A. F. Basedow, H. Bayer, F. Blount, B. Blumer, S. Bodenbender, G. Bourcart, F. E. Branner, J. C. Brooks, A. H. Brougb, B. H. Brown, H. Y. L. Buckman, S. S. Bullen, Rev. E. A. Campbell, W. Cantrill, T. C. Carulla, F. J. E. Cayenx, L. Cbapman, F. Cbesneau, G. Clarke, J. M. Cole, G. A. J. Collet, L. Condon, T. Cooniaraswamy, A. K. Cross, J. Cunningham-Craig, E.H. Dalton, W. H. Daly, E. A. Davis, W. M. Davison, C. Derwies, Mme. Vera de. Dollfus, G. F. Duparc, L. Fisber, E. F. Fisber, Eev. 0. Fox, H. Gagel, C. Gaudry, A. Geikie, Sir Archibald. Gentil, L. Gilbert. G. K. Gcebel, K. Green well, A. Gugenhard, M. HaiTison, J. B. Harrison, W. J. Hatch, F. H. ! Heim, A. i Henriksen, G. Hodson, G. Hogben, G. : Holland, F. I Hopkinson, J. Hornnnff, F. Hull, E. i Hume, W. F. j Issel, A. I Jensen, A. S. ! Jentzsch, A. I Jervis, the late W. F. I Jones, T. E. Jorissen, E. Karpinski, A. I Keidel, H. ( Kerr, W. I Kingsmill, T. W. i Kitson, A. E. j Klein, C. j Knox, A. ; Lacroix, A. Lambe, L. M. Lanrplugh, G. W. Eemoine, P. Lewis, F. J. Loblejr, J. L. Loewinson-Lessing, F. Longstaff, Mrs. Jane. Lowe, H. J. McKay, A. MacLaren, J. M. Marriott, H. F. Martel, E. A. i Martin, E. A. Maslen. A. J. 1 Matley, C. A. Mellor, E. T. j Merrill, G. P. ! Merzbacber, G. Michel Levy, A. Monckton, H. W. I Montessus de Ballore. F. de. Muret, E. Nares, Sir George. Nathorst, A. G. Newton, E. T. Newton, R. B. Omori, F. Parkinson, J. Pearce, F. Pirie, J. H. H. Pjetursson, H. Plotts, W. Preiswerk, H. Pritchard, G. B. Eeade, T. M. Eeed, H. F. Eeid, C. Ei chard son, L. Eichthofen, Baroness F. von. Eosenbusch, H. Eothpletz, A, Eutot, A. Sacco, F. Salter, A. E. Salter, Miss Maiy. Sandberg, C. Sarasin, C. Sawyer, A. E. Scalia, S. S chaffer, F. von. Schmidt, H. Scott, D. H. Sears, J. H. Seward, A. C. Sheppard, T. Sherborn, CD. Solly, E. H. Springer, H. F. Steinmann, G. Stobbs, J. T. Strangways, C. Fox. Suess, E. Sulva, E. Sutcliffe, G. E. Tassin, W. Termier, P. Thompson, B. Thoroddsen, Th. Tobler, A. Tornquist, S. L. Twelvetrees, W. H. Uhlig, V. Ussher, W. A. E. Vaughan, A. Verbeek, E. D. M„ Walford, E. A. Walther, J. Ward, the late J.. Warren, S. H. Weicher, W. Whitaker, W. Wieland, G. E, Wilckens, 0. Woodward, H. Woodward, H. B. Woolacott, D. Wortman, J. L. Wright, J. Yol. 6^.~\ ANNUAL REPORT. xix Comparative Statement of the Number oe the Society at the Close of the Years 1905 and 1906. Compounders Contributing Fellows Non-Contributing Fellows . . Dec. 31st, 1905. Dec. 31st. 1906. 280 273 926 . . . . ' 946 33 32 1239 1251 Foreign Members 40 40 Foreign Correspondents .... 38 39 1317 J 330 Comparative Statement, explanatory of the Alterations in the Number of Fellows, Foreign Members, and Foreign Correspondents at tlie close of the years 1905 and 1906. Number of Compounders, Contributing and Non- 1 -. ^on Contributing Fellows, December 31st, 1905 . . J Add Fellows elected during the former year and 1 - 9 paid in 1906 J lZ Add Fellows elected and paid in 1906 38 1289 Deduct Compounders deceased 12 Contributing Fellows deceased 14 Non-Contributing Fellow deceased 1 Contributing Fellows resigned 7 Contributing Fellows removed 4 — 38 1251 Number of Foreign Members and Foreign Cor- 1 _o respondents, December 31st, 1905 . . J ' Deduct Foreign Member deceased 1 Foreign Correspondent deceased .... 1 Foreign Correspondent elected 1 -, Foreign Member J — 3 75 Add Foreign Member elected 1 Foreign Correspondents efected .... 3 — 4 — 79 1330 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May I907, Barron, T. Churchill, G. G. Clarke, C. B. De Bance, C. E. Dickinson, W. •Garnett-Botfield, AY Deceased Fellows. Compounders (12). E. Hanibly, C. H. B. Langtree, C. AY. ITorris, J. F. Perazzi, Commendatore C. Ricarde-Seaver, Major F. I. Trotter, C. Resident and other Contributing FeUovjs (14). Blake, Eev. J. F. Cunnington, AY. Dewes, H. Dutton, H. B. Emary, P. Eream, Prof. AY. Froglev, J. H. Goodchild, J. G. Goss, W. H. Harris, G. F. Jervis, Car. W. Leighton, T. Ward. J. AYolf, G. de. Non-contributing Fellow (1). Sowerby, W. Deceased Foreign Member (1). Benevier, Prof. E. Deceased Eoeeigx Correspondent (1). Penfield, Prof. S. L. Brown, J. W. Bullock, J. H. Card, G. W. Datta, P. N. Fellows Resigned (7). ! Farrar, S. H. j Slee, W.H.J. I Thompson, W. Vol. 63.] ANNUAL RErORT. Fellows Removed (4). Don, Dr. J. R. Doudas. E. A. Freeman, T. K. Fry, G. M. The following Personage was elected a Foreign Member during the year 1906: — Sohns-Laubach, Count Hermann zu, of Strasburg. The following Personages were elected Foreign Correspondents during the year 1906 :— Prof. John M. Clarke, of Albany, N.Y. (U.S.A.). Prof. William Morris Davis, of Cambridge, Mass. (U.S.A.). Dr. Jakob Johannes Sederliolm, of Helsingfors. After the Reports bad been read, it was resolved : — That they be received and entered on the Minutes of the Meeting, and that such parts of them as the Council shall think fit be printed and circulated among the Fellows. It was afterwards resolved : — That the thanks of the Society be given to Mr. R. S. Herries, retiring from the office of Vice-President. VOL. LXIII. XXil PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [MayiQ^y, That the thanks of the Society be given to Prof. T. G. Bonney, Mr. E. S. Herries, Mr. PhiJip Lake, Mr. Bedford McNeill, and the Eev. IL H. AYinwood, retiring from the Council. After the Ballo ting-Glasses had been closed, and the Lists examined by the Scrutineers, the following gentlemen were declared to have been duly elected as the Officers and Council for the ensuing year : — Vol. 63.-] ANNUAL REPORT. OFFICEES AND COUNCIL.— 1907. PRESIDENT. Sir Archibald Geikie, D.C.L., Sc.D., LL.D., Sec.E.S. VICE-PRESIDENTS. John Edward Marr, Sc.D., F.E.S. Prof. William Johnson Sollas, Sc.D., LL.D., F.E.S. Aubrey Strahan, Sc.D., F.E.S. J. J. Harris Teall, M.A., D.Sc, F.E.S. SECRETARIES. Prof. William W. Watts, M.A., M.Sc, F.E.S. Prof. Edmund J. Garwood, M.A. FOREIGN SECRETARY. Sir John Evans, K.C.B., D.C.L., LL.D., F.E.S., F.L.S. TREASURER. Horace Woollaston Monckton, Treas. L.S. COUNCIL. H. H. Arnold-Bemrose, J.P., M.A. Prof. S. H. Cox, F.C.S., Assoc. E.S.M. Sir John Evans, K.C.B., D.C.L., LL.D., F.E.S. Prof. Edmund J. Garwood, M.A. Sir Archibald Geikie, D.C.L., Sc.D., LL.D., Sec.E.S. W.H.Hudleston,M.A.,F.E.S.,F.L.S. Finlay Lorimer Kitchin, M.A., Ph.D. George William Lamplugh, F.E.S. Prof. Charles Lap worth, M.Sc, LL.D., F.E.S. Richard Lvdekker, B.A., F.E.S. John Edward Marr, Sc.D.. F.E.S. Horace W. Monckton, Treas.L.S. Frederick William Eudler, I.S.O. Prof. William Johnson Sollas, Sc.D.. LL.D., F.E.S. Leonard James Spencer, M.A. Aubrey Strahan, Sc.D., F.E.S. Charles Fox Strangways. J. J. H. Teall. M.A., D.Sc, F.E.S. Eichard Hill Tiddeman, M.A. Prof.W.W.Watts,M.A.,M.Sc;F.E.S. Henry Woods, M.A. Arthur Smith Woodward, LL.D., F.E.S., F.L.S. HoraceBolingbrokeWoodward,F.B.S. c2 XXIV PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1907. LIST OF THE FOREIGN MEMBERS OF THE GEOLOGICAL SOCIETY OF LONDON, in 1906. Date of Election. 1874. Prof. Albert Jean Gaudry, Pans. 1877. Prof. Eduard Suess, Vienna. 1880. Geheimrath Prof. Ferdinand Zirkel, Leipzig. 1884. Commendatore Prof. Giovanni Capellini, Bologna. 1885. Prof. Jules Gosselet, Lille. 1886. Prof. Gustav Tschermak, Vienna. 1888. Prof. Eugene Eenevier, Lausanne. {Deceased.) 1890. Geheimrath Prof. Heinrich Kosenbusch, Heidelberg. 1891. Prof. Charles Barrois, Lille. 1893. Prof. Walderaar Christofer Brcegger, Christiania. 1893. M. Auguste Michel-Levy, Paris. 1893. Dr. Edmund Mojsisovics von Mojsvar, Vienna. 1893. Prof. Alfred Gabriel Nathorst, Stockholm. 1894. Prof. George J. Brush, New Haven, Conn. (U.S.A.). 1894. Prof. Edward Salisburv Dana, New Haven, Conn. (U.S.A.). 1895. Prof. Grove Karl Gilbert, Washington, B.C. (U.S.A.), 1895. Dr. Friedrich Schmidt, St. Petersburg. 1896. Prof. Albert Heim, Zurich. 1897. M. Edouard Dupont, Brussels. 1897. Dr. Anton Eritsch, Prague. 1897. Prof. Albert de Lapparent, Paris. 1897. Dr. Hans Eeusch, Christiania. 1898. Geheimrath Prof. Hermann Credner, Leipzig. 1898. Dr. Charles Doolittle Walcott, Washington. B.C. (U.S.A.). 1899. Prof. Marcel Bertrand, Paris. (Beceased.) 1899. Senhor Joaquini Felipe Nery Delgado, Lisbon. 1899. Prof. Emmanuel Kayser, Marburg. 1899. M. Ernest Van den Broeck, Brussels. 1899. Dr. Charles Abiathar White, Washington, B.C. (U.S.A.). 1900. M. Gustave F. Dollfus, Paris. 1900. Prof. Paul Groth, Munich. 1900. Dr. Sven Leonhard Toernquist, Lund. 1901. M. Alexander Petrovich Karpinsky, St. Petersburg. 1901. Prof. Alfred Lacroix, Paris. 1903. Prof. Albrecht Penck, Berlin. 1903. Prof. Anton Koch, Budapest. 1904. Prof. Joseph Paxson Iddings, Chicago (U.S.A.). 1904. Prof. Henry Fairfield Osborn, New Fork (U.S.A.). 1905. Prof. Louis Dollo, Brussels. 1905. Prof. August Rothpletz, Munich. 1906. Prof. Count Hermann zu Solms-Laubach, Strasburg. Vol. 63.] ANNUAL EEPOBT. XXV LIST OF THE FOREIGN CORRESPONDENTS OF THE GEOLOGICAL SOCIETY OF LONDON, in 1906. Date of Election. ] 874. Prof. Igiuo Cocchi, Florence. 1879. Dr. II. Emile Sauvage, Boulogne-sur-Mer. 1889. Dr. Rogier Diederik Marius Yerbeek, The Hague. 1890. Geheimer Bergratli Prof. Adolpli von Kcenen, Gottingen. 1892. Prof. Johann Lehmann, Kiel. 1893. Prof. Alexis P. Pavlow, Moscow. 1893. M. Ed. Rigaux, Boulogne-sur-Mer. 1894. M. Perceval de Loriol-Lefort, Campagne Frontenex, near Geneva. 1894. Dr. Francisco P. Moreno, La Plata. 1894. Prof. J. H. L. Vogt, Christiania. 1895. Prof. Constantin de KroustchofF, St. Petersburg. 1896. Prof. Samuel L. Penfield, New Haven, Conn. ( U. S. A.). (Deceased.) 1896. Prof. Johannes Walther, Halle an der Saale. 1897. M. Emmanuel de Margerie, Paris. 1897. Prof. Count Hermann zu Solms-Laubacli, Strasburg. (Elected Foreign Member?) 1898. Dr. Marcellin Boule, Paris. 1898. Dr. W. H. Dall, Washington, B.C. (U.S.A.). 1899. Dr. Gerhard Holm, Stockholm. 1899. Prof. Theodor Liebisch, Gottingen. 1899. Prof. Franz Loewinson-Lessing, St. Petersburg. 1899. M. Michel F. Mourlon, Brussels. 1899. Prof. Gregorio Stefanescu, Bucharest. 1899. Prof. Rene" Zeiller, Paris. 1900. Commendatore Prof. Arturo Issel, Genoa. 1900. Prof. Ernst Koken, Tubingen. 1900. Prof. Federico Sacco, Turin. 1901. Prof. Friedrich Johann Becke, Vienna. 1902. Prof. Thomas Chrowder Chamberlin, Chicago, III. (U.S.A.). 1902. Dr. Thorvaldr Thoroddsen, Copenhagen. 1902. Prof. Samuel Wendell Williston, Chicago, III. (U.S.A.). 1903. Geheimer Bergrath Prof. Carl Klein, Berlin. 1903. Dr. Einil Ernst August Tietze, Vienna. 1904. Dr. William Bullock Clark, Baltimore (U.S.A.). 1904. Dr. Erich Dagobert von Drygalski, Charlottenburg. 1904. Prof. Giuseppe de Lorenzo, Naples. 1904. The Hon. Frank Springer, Burlington, Iowa (U.S.A.). 1904. Dr. Henry S. Washington, Locust, N.J. ( U.S.A.). 1905. Prof. Bundjiro Koto, Tokyo. 1906. Prof. John M. Clarke, Albany, N. Y. ( U.S.A.). 1906. Prof. William Morris Davis, Cambridge, Mass. (U.S.A.). 1906. Dr. Jakob Johannes Sederholm, Helsingfors. xxri PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. [^Lay I9°7 ' ■> AWARDS OF THE WOLL ASTON MEDAL UNDER THE CONDITIONS OF THE ' DONATION FUND ' ESTABLISHED BY WILLIAM HYDE WOLLASTON, M.D., F.R.S., F.G.S., etc. To promote researches concerning the mineral structure of the Earth, and to enable the Council of the Geological Society to reward those individuals of any country by whom such researches may hereafter be made,' — ' such individual not being a Member of the Council.' 1843. 1831. Mr. William Smith. 1835. Dr. Gideon A. Mantell. 1836. M. Louis Agassiz. 1837 ICapt. T. P. Cautley. ( Dr. H. Falconer. 1838. Sir Richard Owen. 1839. Prof. C. G. Ehrenberg. 1840. Prof. A. H. Dumont. 1841. M. Adolphe T. Brongniart. 1842. Baron Leopold von Buch. M. Erie de Beaumont. M. P. A. Dufrenoy. 1844. The Rev. W. D. Conybeare. 1845. Prof. John Phillips. 1846. Mr. William Lonsdale. 1847. Dr. Ami Boue. 1848. The Very Rev. W . Buckland 1849. Sir Joseph Prestwich. 1850. Mr. William Hopkins. 1851. The Rev. Prof. A. Sedgwick. 1852. Dr. W. H. Fitton. M. le Vicomte A. d'Archiac, M. E. de Verneuil. 1854. Sir Richard Griffith. 1855. Sir Henry De la Beche. 1856. Sir William Logan. 1857. M. Joachim Barrande. J Herr Hermann von Meyer 18°8- 1 Prof. James Hall. 1859. Mr. Charles Darwin. 1860. Mr. Searles V. Wood. 1861. Prof. Dr. H. G. Bronn. 1862. Mr. R. A. C. Godwin- Austen. ! 1863. Prof. Gustav Bischof. 1864. Sir Roderick Murchison. 1865. Dr. Thomas Davidson. 1866. Sir Charles Lyell. 1867. Mr. G. Poulett Scrope. 1868. Prof. Carl F. Naumann. 1869. Dr. Henry C. Sorby. 1853. 1870. Prof. G. P. Deshayes. 187].. Sir Andrew Ramsay. 1872. Prof. James D. Dana. 1873. Sir P. de M. Grey Egerton. 1874. Prof. Oswald Heer. 1875. Prof. L. G. de Koninck. 1876. Prof. Thomas H. Huxley. 1877. Mr. Robert Mallet. 1878. Dr. Thomas Wright. 1879. Prof. Bernhard Studer. 1880. Prof. Auguste Daubree. 1881. Prof. P. Martin Duncan. 1882. Dr. Franz Ritter von Hauer. 1883. Dr. William Thomas Blanford. 1884. Prof. Albert Jean Gaudry. 1885. Mr. George Busk. 1886. Prof. A. L. O. Des Cloizeaux. 1887. Mr. John Whitaker Hulke. 1888. Mr. Henry B. Medlicott. 1 889. Prof. Thomas George Bonney. 1890. Prof. W. C. Williamson. 1891. Prof. John Wesley Judd. 1892. Baron Ferdinand von Richthofen. 1893. Prof. IS'evil Story Maskelyne. 1894. Prof. Karl Alfred von Zittel. 1895. Sir Archibald Geikie. 1896. Prof. Eduard Suess. 1897. Mr. Wilfrid H. Hudlestou. 1898. Prof. Ferdinand Zirkel. 1899. Prof. Charles Lapworth. 1900. Prof. Grove Karl Gilbert. 1901. Prof. Charles Barrois. 1902. Dr. Friedrich Schmidt. 1903. Prof. Heinrich Rosenbusch. 1904. Prof. Albert Heim. 1905. Dr. J. J. Harris Teall. 1906. Dr. Henry Woodward. 1907. Prof. William J. Sollas. Vol. 63. ANNUAL REPORT. AWARDS BALANCE OF THE PROCEEDS OF THE WOLLASTON < DONATION-FUND.' 1831. Mr. William Smith. 1833. Mr. William Lonsdale. 1834. M. Louis Agassiz. 1835. Dr. Gideon A. Mantell. 1836. Prof. O. P. Deshayes. 1838. Sir Richard Owen. 1839. Prof. C. G. Ehrenberg. 1840. Mr. J. De Carle Sowerby. 1841. Prof. Edward Forbes. 1842. Prof. John Morris. 1843. Prof. John Morris. 1844. Mr. William Lonsdale. 1845. Mr. Geddes Bain. 1846. Mr. William Lonsdale. 1847. M. Alcide d'Orbigny. J Cape-of-Good-Hope Fossils. 184b' }M. Alcide d'Orbigny. 1849. Mr. William Lonsdale. 1850. Prof. John Morris. 1851. M. Joachim Barrande. 1852. Prof. John Morris. 1853. Prof. L. G. de Koninck. 1854. Dr. Samuel P. Woodward. 1855. Drs. G. and F. Sandberger. 1856. Prof. G. P. Deshayes. 1857. Dr. Samuel P. Woodward. 1858. Prof. James Hall. 1859. Mr. Charles Peach. 1 Prof. T. Rupert Jones. 186°- IMr. W.K.Parker. 1861. Prof. Auguste Daubree. 1862. Prof. Oswald Heer. 1863. Prof. Ferdinand Senft. 1864. Prof. G. P. Deshayes. 1865. Mr. J. W. Salter. 1866. Dr. Henrv Woodward. 1867. Mr. W. H. Baily. 1868. M. J. Bosquet. 1869. Mr. William Carruthers. 1870. M. Marie Rouault. 1871. Mr. Robert Etheridge. 1872. Dr. James Croll. 1873. Prof. John Wesley Judd. 1874. Dr. Henri Nyst. 1875. Prof. Louis C. Miall. 1876. Prof. Giuseppe Seguenza. 1877. Mr. Robert Etheridge, Jun. 1878. Prof. William Johnson Sollas. 1879. Mr. Samuel Allport. 1880. Mr. Thomas Davies. 1881. Dr.RamsayHeatleyTraquair. 1882. Dr. George Jennings Hinde. 1883. Prof. John Milne. 1884. Mr. Edwin Tulley Newton. 1885. Dr. Charles Callaway. 1886. Mr. J. Starkie Gardner. 1887. Dr. Benjamin Neeve Peach. 1888. Dr. John Home. 1889. Dr. Arthur Smith Woodward. 1890. Mr. William A. E. Ussher. 1891. Mr. Richard Lydekker. 1892. Mr. Orville Adelbert Derby. 1893. Mr. John George Goodchild. 1894. Mr. Aubrey Strahan. 1895. Prof. William W. Watts. 1896. Mr. Alfred Harker. 1897. Dr. Francis Arthur Bather. 1898. Prof. Edmund J. Garwood. 1899. Prof. John B. Harrison. 1900. Dr. George Thurland Prior. 1901. Mr. Arthur Walton Rowe. 1902. Mr. Leonard James Spencer. 1903. Mr. L. L. Belinfante. 1904. Miss Ethel M. R. Wood. 1905. Mr. H. H. Arnold-Bemrose. 1906. Dr. Finlay Lorimer Kitchin. 1907. Dr. Arthur Vaughan. Xviil PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [May I907, AWARDS OF THE MURCHISON MEDAL UNDER THE CONDITIONS OF THE 'MURCHISON GEOLOGICAL FUND/ ESTABLISHED UNDER, THE WILL OE THE LATE SIR RODERICK IMPEY MURCHISON, Bart., E.R.S., E.G.S. To be applied in every consecutive year, in such manner as the Council of the Society may deem most useful in advancing Geological Science, whether by granting sums of money to travellers in pursuit of knowledge, to authors of memoirs, or to persons actually employed in any enquiries bearing upon the science of Geology, or in rewarding any such travellers, authors, or other persons, and the Medal to be given to some person to whom such Council shall grant any sum of money or recompense in respect of Geological Science.' 1873. Mr. William Davies. 1874. Dr. J. J. Bigsby. 1875. Mr.W. J. Henwood. 1876. Mr. Alfred R. 0. Selwyn. 1877. The Rev. W. B. Clarke. 1878. Prof. Harms Bruno Geinitz. 1879. Sir Frederick M'Coy. 1880. Mr. Robert Etheridge. 1881. Sir Archibald Geikie. 1882. Prof. Jules Gosselet. 1883. Prof. H. R. Goeppert. 1884. Dr. Henry Woodward. 1885. Dr. Ferdinand von Rcemer. 1886. Mr. William Wbitaker. 1887. The Rev. Peter B. Brodie. 1888. Prof. J. S. Newberry. 1889. Prof. James Geikie. 1890. Prof. Edward Hull. 1891. Prof. Waldemar C. Brcegger. 1892. Prof. A. H. Green. 1893. The Rev. Osmond Fisher. 1894. Mr. William T. Aveline. 1895. Prof. Gustaf Lindstroem. 1896. Mr. T. Mellard Reade. 1897. Mr. Horace B. Woodward. 1898. Mr. Thomas F. Jamieson. J Dr. Benjamin N. Peach. 1899. jDr> j^ Etae. 1900. Baron A. E. Nordenskiceld. 1901. Mr. A. J. Jukes-Browne. 1902. Mr. Frederic W. Harmer. 1903. Dr. Charles Callaway. 1904. Prof. George A. Lebour. 1905. Mr. Edward John Dunn. 1906. Mr. Charles T. dough. 1907. Mr. Alfred Harker. Vol. 63.] ANNUAL EEPORT. AWARDS OF THE BALANCE OF THE PROCEEDS OF THE 'MURCHISON GEOLOGICAL FUND.' 1873. Prof. Oswald Heer. 1874. Mr. Alfred Bell. 1874. Prof. Ralph Tate. 1875. Prof. H. Govier Seeley. 1876. Dr. James Croll. 1877. The Rev. John F. Blake. 1878. Prof. Charles Lapworth. 1879. Mr. James Walker Kirkby. 1880. Mr. Robert Etheridge. 1881. Mr. Frank Rutley. 1882. Prof. Thomas Rupert Jones. 1883. Dr. John Young. 1884. Mr. Martin Simpson. 1885. Mr. Horace B. Woodward. 1886. Mr. Clement Reid. 1887. Mr. Robert Kidston. 1888. Mr. Edward Wilson. 1889. Prof. Grenville A. J. Cole. 1890. Mr. Edward B. Wethered. 1891. The Rev. Richard Baron. 1892. Mr. Beebv Thompson. 1893. Mr. Griffith J. Williams. 1894. Mr. George Barrow. 1895. Mr. Albert Charles Seward. 1896. Mr. Philip Lake. 1897. Mr. Sydney S. Buckman. 1898. Miss Jane Donald. 1899. Mr. James Bennie. 1900. Mr. A. Vaugkan Jennifers. 1901. Mr. Thomas's. Hall. 1902. Mr. Thomas H. Holland. 1903. Mrs. Elizabeth Gray. 1904. Dr. Arthur Hutchinson. 1905. Mr. Herbert Lister Bowman. 1906. Dr. Herbert Lapworth. 1907. Dr. Felix Oswald. XXX PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May I907, AWARDS OF THE LYELL MEDAL UNDER THE CONDITIONS OF THE 'LYELL GEOLOGICAL FUND/ ESTABLISHED UNDER THE WILL AND CODICIL OF THE LATE SIR CHARLES LYELL, Bart., F.R.S., F.G.S. The Medal ' to be cast in bronze and to be given annually ' (or from time to time) 'as a mark of honorary distinction and as an expression on the part of the governing body of the Society that the Medallist (who may be of any country or either sex) has deserved well of the Science,' — ' not less than one third of the annual interest [of the fund] to accompany the Medal, the remaining interest to be given in one or more portions, at the discretion of the Council, for the encouragement of Geology or of an}' of the allied sciences by which thej' shall consider Geology to have been most materially advanced, either for travelling expenses or for a memoir or paper published, or in progress, and without reference to the sex or nationality of the author, or the language in which any such memoir or paper may be written.' There is a further provision for suspending the award for one year, and in such case for the awarding of a Medal to ' each of two persons who have been jointly engaged in the same exploration in the same country, or perhaps on allied subjects in different countries, the proportion of interest always not being less to each Medal than one third of the annual interest.' 1876. Prof. John Morris. | 1893. Mr. Edwin Tulley Newton. 1877. Sir James Hector. j 1894. Prof. John Milne. 1878. Mr. George Busk. 1895. The Rev. John F. Blake. 1879. Prof. Edmond Hebert. \ 1896. Dr. Arthur Smith Woodward. 1880. Sir John Evans. 1897. Dr. George Jennings Hinde. 1881. Sir J. William Dawson. 1898. Prof. Wilhelm Waagen. 1882. Dr. J. Lycett. 1899. Lt.-Gen. C. A. McMahon. 1883. Dr. W. B. Carpenter. 1900. Dr. John Edward Marr. 1884. Dr. Joseph Leidy. 1901. Dr.Ramsay Heatley Traquair. 1885. Prof. H. Govier Seeley. f Prof. Anton Fritsch. 1886. Mr. William Pengelly. "* I Mr. Richard Lydekker. 1887. Mr. Samuel Airport. 1903. Mr. Frederick William Rudler. 1888. Prof. Henry A. Nicholson. ! 1904. Prof. Alfred Gabriel Nathorst. 1889. Prof. W. Boyd Dawkins. | 1905. Dr. Hans Reusch. 1890. Prof. Thomas Rupert Jones. 1906. Prof. Frank Dawson Adams. 1891. Prof. T. McKenny Hughes. 1907. Dr. Joseph F. Whiteaves. 1892. Mr. George H. Morton. Vol. 62.] ANNUAL REPORT. AWARDS OF THE BALANCE OF THE PROCEEDS OF THE 'LYELL GEOLOGICAL FUND.' 1876. Prof. John Morris. 1877. Mr. William Pengeily. 1878. Prof. Wilhemi Waagen. 1879. Prof. Henry A. Nicholson. 1879. Dr. Henry Woodward. 1880. Prof. F. A. von Quenstedt. 1881. Prof. Anton Fritsch. 1881. Mr. G. R. Vine. 1882. The Rev. Norman Glass. 1882. Prof. Charles Lapworth. 1883. Mr. P. H. Carpenter. 1883. M. Ed. Rigaux. 1884. Prof. Charles Lapworth. 1885. Mr. Alfred J. Jukes-Browne. 1886. Mr. David Mackintosh. 1887. The Rev. Osmond Fisher. 1888. Dr. Arthur H. Foord. 1888. Mr. Thomas Roberts. 1889. M. Louis Dollo. 1890. Mr. Charles Davies Sherborn. 1891. Dr. C. I. Forsyth Major. 1891. Mr. George W. Lamplugh. 1892. Prof. John Walter Gregory. 1892. Mr. Edwin A. Walford. 1893. Miss Catherine A. Raisin. 1893. Mr. Alfred N. Leeds. 1894. Mr. William Hill. 1895. Prof. Percy Fry Kendall. 1895. Mr. Benjamin Harrison. 1896. Dr. William F. Hume. 1896. Dr. Charles W. Andrews. 1897. Mr. W. J. Lewis Abbott. 1897. Mr. Joseph Lomas. 1898. Mr. William H. Shrubsole. 1898. Mr. Henry Woods. 1899. Mr. Frederick Chapman. 1899. Mr. John Ward. 1900. Miss Gertrude L. Elles. 1901. Dr. John William Evans. 1901. Mr. Alexander McHenry. 1902. Dr. Wheelton Hind. 1903. Mr. Sydney S. Buckman. 1903. Mr. George Edward Dibley. 1904. Dr. Charles Alfred Matley. 1904. Prof. Sidney Hugh Reynolds. 1905. Mr. E. A. Newell Arber. 1905. Mr. Walcot Gibson. 1906. Mr. William G. Fearnsides. 1906, Mr. Richard H. Solly. 1907. Mr. T. Crosbee Cantrill. 1907. Mr. Thomas Sheppard. xxxn PEOCEEDIISTGS OP THE GEOLOGICAL SOCIETY. [May I907, AWARDS OF THE BIG SB Y MEDAL, FOUNDED BY THE LATE Db. J. J. BIGSBY, F.E.S., F.G.S. To be awarded biennially ' as an acknowledgment of eminent services in any depart- ment of Geology, irrespective of tbe receiver's country; but be must not be older than 45 years at bis last birthday, thus probably not too old for further work, and not too young to have done much.' 1877. Prof. Othniel Charles Marsh. 1879. Prof. Edward Drinker Cope. 1881. Prof. Charles Barrois. 1883. Dr. Henry Hicks. 1885. Prof. Alphonse Renard. 1887. Prof. Charles Lapworth. 1889. Dr. J. J. Harris Teall. 1891. Dr. George Mercer Dawson. 1893. Prof. William Johnson Sollas. 1895. Mr. Charles D. Walcott. 1897. Mr. Clement Reid. 1899. Prof. T. W. E. David. 1901. Mr. George W. Lamplugh. 1903. Dr. Henry M. Ami. 1905. Prof. John Walter Gregory. 1907. Mr. Arthur W. Rogers. AWARDS OF THE PRESTWICH MEDAL, ESTABLISHED UNDER THE WILL OF THE LATE SIR JOSEPH PRESTWICH, F.R.S., F.G.S. To apply the accumulated annual proceeds ... at the end of every three years, in providing a Gold Medal of the value of Twenty Pounds, which, with the remainder of the proceeds, is to be awarded ... to the person or persons, either male or female, and either resident in England or abroad, who shall have done well for the advancement of the science of Geology ; or, from time to time to accumulate the annual proceeds for a period not exceeding six years, and apply the said accumulated annual proceeds to some object of special research bearing on Stratigraphical or Physical Geology, to be carried out by one single individual or by a Committee; or, failing these objects, to accumulate the annual proceeds for either three or six years, and devote such proceeds to such special purposes as may be decided.' 1903. John Lubbock, Baron Avebury. 1906. Mr. William Wrhitalrer. Vol. 63.-] ANNUAL 11EP0ET. XXX111 AWARDS OF THE PROCEEDS OF THE BARLOW- JAMESON FUND, ESTABLISHED UNDER THE WILL OF THE LATE Dr. H. C. BARLOW, F.G-.S. The perpetual interest to be applied every two or three years, as may be approved by the Council, to or for the advancement of Geological Science.' 1879. Purchase of Microscope. 1881. Purchase of Microscope - Lamps. 1882, Baron C. von Ettingshausen. 1884. Dr. James Croll. 1884. Prof. Leo Lesquereux. 1886. Dr. H. J. Johnston-Lavis. 1888. Museum. 1890. Mr. W. Jerome Harrison. 1892. Prof. Charles Mayer-Eyniar. 1893. Purchase of Scientific In- struments for Capt. F. E, Younghusband. 1894. Dr. Charles Davison. 1896. Mr. Joseph Wright. 1896. Mr. John Storrie. 1898. Mr. Edward Greenly. 1900. Mr. George C. Crick. 1900. Prof. Theodore T. Groom. 1902. Mr. William M. Hutchings. 1904. Mr. Hugh J. LI. Beadnell. 1906. Mr. Henry 0. Beasley. AWARDS OF THE PROCEEDS OF THE 'DANIEL-PIDGEON FUND/ FOUNDED BY MRS. PIDGEON, IN ACCORDANCE WITH THE WILL OF THE LATE DANIEL PIDGEON, P.G.S. An annual grant derivable from the interest on the Fund, to be used at the discretion of the Council, in whatever way may in their opinion best promote Geological Original Kesearch, their Grantees being in all cases not more than twenty-eight years of age.' 1903. Prof. Ernest Willington Skeats. 1904. Mr. Linsdall Richardson. 1905. Mr. Thomas Vipond Barker. 1906. Miss Helen Drew. XXxiv PEOCEEDIN-&S OF THE GEOLOGICAL SOCIETY. [May I907, Estimates for INCOME EXPECTED. £ s. d. £ s. d. Compositions 205 0 0 Due for Arrears of Admission-Fees 94 10 0 Admission-Fees, 1907 228 12 0 323 2 0 Arrears of Annual Contributions 140 0 0 Annual Contributions, 1907, from Resident and Non-Resident Fellows 1780 0 0 Annual Contributions in advance 50 0 0 1970 0 0 Sale of Quarterly Journal, including Longmans' Account 160 0 0 Sale of History of the Geological Society 50 0 0 Sale of Transactions, General Index, Library- Catalogue, Museum - Catalogue, Hutton's ' Theory of the Earth ' vol. iii, Hochstetter's ' New Zealand,' and List of Fellows 6 0 0 Dividends on £2500 India 3 per cent. Stock . . 75 0 0 Dividends on £300 London, Brighton, & South Coast Railway 5 per cent. Consolidated Pre- ference-Stock 15 0 0 Dividends on £2250 London & North-Western Railway 4 per cent. Preference-Stock 90 0 0 Dividends on £2800 London & South- Western Railway 4 per cent. Preference-Stock 112 0 0 Dividends on £2072 Midland Railway 2| per cent. Perpetual Preference-Stock 51 16 0 Dividends on £267 6s. 7d. Natal 3 per cent. Stock. 8 0 0 351 16 0 3065 18 0 Estimated excess of Expenditure over Income 247 0 0 £3312 18 0 Vol. 63.^ FINANCIAL REP0KT. XXXV the Year 1907. EXPENDITURE ESTIMATED. £ 5. (I. £ s. d. House-Expenditure : Taxes 15 0 Fire-insurance 15 0 0 Electric Lighting and Maintenance 50 0 0 Gas 12 0 0 Fuel SO 0 0 Furniture and Repairs 25 0 0 House-Repairs and Maintenance 50 0 0 Annual Cleaning 15 0 0 Tea at Meetings 20 0 0 Washing and Sundry Expenses 35 0 0 252 15 0 Salaries and Wages, etc. : Assistant-Secretary 350 0 0 ,, half Premium Life-Insurance... 10 15 0 Assistant-Librarian 150 0 0 Assistant-Clerk 150 0 0 Junior Assistant 80 0 0 House-Porter and Upper Housemaid 95 0 0 Under Housemaid 48 18 0 Charwoman and Occasional Assistance 10 0 0 Accountants' Fee 10 10 0 905 3 0 Office-Expenditure : Stationery 35 0 0 Miscellaneous Printing, etc 50 0 0 Postages and Sundry Expenses 80 0 0 165 0 0 Library (Books and Binding) 220 0 0 Library-Catalogue : . Cards 20 0 0 Compilation 50.0 0 70 0 0 Publications: Quarterly Journal, including Commission on Sale 1000 0 0 Postage on Journal, Addressing, etc 90 0 0 Record of Geological Literature 1 40 0 0 List of Fellows 35 0 0 Abstracts, including Postage 110 0 0 ^History of the Geological Society 175 0 0 1550 0 0 ^Centenary Expenditure ' 150 0 0 * These items are in the nature of capital expenditure, or are not likely to recur. £3312 18 0 HORACE W. MONCKTON, Treasurer. January 25th, 1907. XXXvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1907, Income and Expenditure during the EECEIPTS. £ s. d. £ s. d. To Balance in the hands of the Bankers at January 1st, 1906 288 15 7 ,, Balance in the hands of the Clerk at January 1st, 1906 16 7 2 305 2 9 ,, Compositions 177 2 0 ,, Admission-Fees : Arrears 75 12 0 Current 233 2 0 303 14 0 ,, Arrears of Annual Contributions . . . . 88 11 6 „ Annual Contributions for 1906 : — Eesident Fellows 1768 4 0 Non-Resident Fellows , 7 17 6 .. Annual Contributions in advance .... 50 80 1915 1 0 „ Publications : Sale of Quarterly Journal : * Vols, itolxi 105 5 3 VoLlxii 49 3 10 154 9 1 „ General Index (Quarterly Journal) . 15 0 „ Abstracts 1 0 „ Record of Geological Literature ... 19 0 „ List of Fellows 4 0 „ Transactions 10 0 „ Hutton's'Theorv of the Earth,' vol. iii 2 6 3 16 „ Miscellaneous Eeceipts 8 12 6 „ Repayment of Income Tax (1 year) 17 11 8 „ Interest on Deposit Account 10 12 3 ... Prestwich Trust-Fund, part repayment of advance for Die of Medal 14 10 0 „ Dividends (less Income-Tax) : — =£2500 India 3 per cent. Stock 71 5 0 £'300 London, Brighton, & South Coast Rail- way 5 per cent. Consolidated Prefer- ence-Stock 14 5 0 £'2250 London & North-Western Railway 4 per cent. Preference-Stock 85 10 0 £2800 London & South-Western Railway 4 per cent. Preference-Stock 106 8 0 £2072 Midland Railway 2\ per cent. Per- petual^ Preference- Stock 49 4 2 £267 6s. Id. Natal 3 per cent. Stock 7 12 4 334 4 6 A further sum of £81 8s. od. is due from Long- .£3249 1 3 mans & Co. for Journal- Sales. -— Vol. 63.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. lxxiii April 17th, 1907. Sir Archibald Geikie, D.C.L., Sc.D., Sec.B.S., President, in the Chair. Allan Arthur Davidson, Mining Engineer, c/o the Bank of Tarapaca & Argentina, Coquimbo (Chile) ; Hugh Michell Luttman- Johnson, Mining Engineer, Rand Club, Johannesburg (Transvaal) ; James Henry Ronaldson, Consulting Mining Engineer, P.O. Box 5224, Johannesburg (Transvaal) ; Francis L. G. Simpson, Mining Engineer, Mohpani Mines, Central Provinces (India) ; and John Edward Wilson, Dunholm, Ilkley-in-Wharfedale (Yorkshire), were elected Eellows of the Society. The List of Donations to the Library was read. The President announced that a Special Genera] Meeting would be held on Wednesday, May 15th, 1907, at 7.30 p.m., for the purpose of considering and voting on the following proposed New Section, and Alterations in existing Sections, of the Bye-Laws : — Proposed jS"ew Section oe the Bye-Laws — Associates. ' 1. — Any woman who has distinguished herself as a geological investigator, or who has shown herself able and willing to communicate to the Society- original and important geological information, or who has exercised signal liberality towards the Society, and is desirous of being elected, provided she be a British subject, or be domiciled in the British dominions or their dependencies, may, subject to the provisions hereinafter contained, be elected an Associate, the number elected being limited to forty. ' 2. — A book shall be kept at the House of the Society, in which Fellows may enter the names and qualifications of women whom such Fellows recommend as Associates, together with a statement that any woman so recommended is desirous of being elected. '■ 3. — So soon as convenient after a name has been entered in the book, the Council shall, provided there be a vacancy, consider whether such name shall be submitted to a ballot of the Fellows as an Associate ; or, if there be more names entered in the book than there are vacancies, the Council shall select which, if any, of such names shall be so submitted to ballot. ' 4. — The name or names so selected shall be read aloud at two Ordinary General Meetings, and balloted for at the next Ordinary General Meeting, under the same regulations as with Candidates for Admission into the Society as Fellows, so far as such regulations are applicable ; but the Certificate shall be in a form similar to that permitted in the case of Foreign Members and Foreign Correspondents, except that it must state that the Candidate is desirous of becoming an Associate. ' 5. — The Secretary shall without delay inform every newly-elected Associate of the fact of her Election, and shall at the same time send her a printed copy •of the Obligation, No. II in Appendix B, except that the word ' an Associate ' shall be therein substituted for ' a Fellow,' together with a copy of the Charter and Bye-Laws of the Society, a list of the Fellows and Associates, and a Card announcing the days on which the Society will hold its meetings during the Session, 1 6. — So soon as such newly elected-Associate has paid her Contribution for the current year and has returned the Obligation, signed by herself and .addressed to the Secretary at the House of the Society, but not before, she VOL. lxiii. q lxxiv PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [Aug. I907, shall be entitled to such privileges as are hereinafter set forth, and her name shall be entered in the list of Associates ; but, unless she pay the Contribution for the current year, and return the Obligation signed and addressed as afore- said -within two calendar months from the day of her Election, or within such further time as the Council may grant upon special cause to them shown, the election of such Associate shall be void. « 7. — Section V (Withdrawing and Eemoval of Fellows) shall apply, as nearly as may be, to Associates. ' 8.— Associates shall not be liable to pay any Admission-Fee. ' 9.— The Annual Contribution to be paid by Associates shall be One Pound One Shilling, due on each successive 1st of January, and payable in advance for the current year. The further provisions of Section VI (Contributions of Fellows) shall apply, a3 nearly as may be, to Associates. • 10. — Associates shall be entitled to be present but not to vote at Ordinary General Meetings ; and at such parts of the Annual General Meetings as may be attended by visitors in accordance with the regulations of the Council for the time being in force, but they shall not be entitled to vote or to propose questions or to comment on the Eeport of the Council or affairs of the Society at such Annual General Meetings ; they shall be entitled to introduce Visitors at Ordinary General Meetings, subject to such regulations as the Council may make from time to time ; to receive such of the Publications of the Society as are sent free of charge to Fellows, and to purchase other Publications of the Society at the reduced prices allowed to Fellows ; and, under such limitations as the Council may deem expedient, to have personal access to the Library, Museum, and all other public rooms in the House of the Society, and to borrow books, maps, plates, drawings, or specimens, belonging to the Society ; but they shall have no share or interest in the property of the Society, nor shall they have any other privileges enjoyed by Fellows, except as expressly herein provided. ' 11. — Associates shall be bound by the Charter and Bye-Laws of the Society, and by all regulations and orders made and issued from time to time by the Council in accordance with the powers conferred on them by the Charter and Bye-Laws. ' 12. — A Register of Associates shall be kept in the same manner as that of Fellows, Foreign Members, and Foreign Correspondents.' Proposed Alterations in existing Bye-Laws. (a) That Bye-Law VI, Art. 4 be repealed, and the following substi- tuted : — ' Every Fellow, if elected before June 30th, shall be subject to the Contribution for the current year ; but, if elected in November or December, he shall pay no Contribution nor shall he be entitled to receive the Publications for the current year.' (b) That in Bye-Law XIII, Art. 18 ' and by cheques .... other Members' be repealed, and the following substituted : — ' and by cheques drawn and signed in such manner as the Council shall direct.' The following communications were read : — 1. ' The Toadstones of Derbyshire : their Field-Relations and Petrography.' By Henry Howe Arnold-Bemrose, J.P., M.A., F.G.S. 2. ' Data bearing on the Age of Niagara Falls.' x By Prof. Joseph William Winthrop Spencer, A.M., Ph.D., F.G.S. 1 Withdrawn by permission of the Council. Vol. C^.^ PROCEEDINGS OF THE GEOLOGICAL SOCIETY. lxXV The following specimens and maps were exhibited : — Eock-specimens, lantern-slides, and microscope rock-sections, exhibited by H. H. Arnold-Bemrose, J.P., M.A., F.G.S., in illus- tration of his paper. A boulder of gneiss (weighing 3 lbs. 5 oz.) from the Rhynckonella- Cuvieri Chalk of Cuxton, Rochester, exhibited by G. E. Dibley, E.G.S. Sheets 59, 60-62, 65, 74 & 75, and 83 of the 1-inch geological map of No^a Scotia, presented by the Director of the Geological Survey of Canada. May 1st, 1907. Sir Archibald Geizie, D.C.L., Sc.D., Sec.E.S., President, in the Chair. The List of Donations to the Library was read. The President read, for the second time, the announcement convening a Special General Meeting for "Wednesday, May 15th, 1907, at 7.30 p.m., to consider and vote on a proposed New Section, and on Alterations in existing Sections of the Eye-Laws. The following communications were read : — 1. ' On the Xerophytic Character of Coal-Plants, and a Suggested Origin of Coal-Beds.' Ey the Eev. Prof. George Henslow, M.A., F.L.S., E.G.S. 2. ' Petrological Notes on the Igneous Eocks lying to the South- East of Dartmoor.' x By Harford John Lowe, E.G.S. The following specimens and maps were exhibited : — Specimens of plants, sections, and lantern-slides, exhibited by the Eev. Prof. G. Henslow, M.A., E.L.S., E.G.S., in illustration of his paper. Hand-specimens and microscope-sections of igneous rocks from the district south-east of Dartmoor, exhibited by H. J. Lowe, E.G.S. , in illustration of his paper. Twelve sheets of the 6 -inch Geological-Survey Map of Scotland : n. s., Edinburgh, presented by the Director of H.M. Geological Survey. 1 Withdrawn by permission of the Council. Ixxvi PKOCEEDLXGS OF THE GEOLOGICAL SOCIETY. [Aug. I907, May 15th, 1907. Sir Archibald Geikie, D.C.L., Sc.D., Sec.B.S., President, in the Chair. George Guillaume Andre, Assoc.M.Inst.C.E., Bosemount, Frittenden (Kent) ; Frederic Ernest Coe, c/o The Bank of Africa, Johannesburg (Transvaal) ; Arthur Leighton Finch, B.Sc. (Lond.), Widnes Secondary School, Appleton Road, Widnes ; Cecil Sidney Ramsden, M.Inst.M.E., Park Hill, Worsley, near Manchester ; and Edwin James Yallentine, Fairlight, Forest Road, Chingford (Essex), were elected Fellows of the Society. The List of Donations to the Library was read. The President announced that the Council had resolved to award the Proceeds of the Daniel-Pidgeon Fund for 1907 to Miss Ida L. Slatee, B.A. (Dublin), jSTewnham College, Cambridge, who proposes to investigate the Lower Palaeozoic rocks in the neighbourhood of Llandeilo. The following communication was read : — ' On the Origin of certain Canon-like Yalleys associated with Lake-like Areas of Depression/ By Frederic William Harmer, F.G.S., F.B.Met.S. The following maps, etc. were exhibited : — MS. maps and lantern-slides, exhibited by F. W. Harmer, F.G.S., F.B.Met.S., in illustration of his paper. Coloured Ordnance-Survey Maps of four Counties, exhibited by Prof. W. W. Watts, M.A., M.Sc, F.B.S., Sec.G.S. Four sheets of the Geological-Survey 6-inch Map of Cumberland, presented by the Director of H.M. Geological Survey. A photograph of the James D. Dana Monument, Dana Park, Albany (N.Y.), presented by Prof. J. M. Clarke, LL.D., F.C.G.S. At a Special General, Meeting, held at 7.30 p.m., the proposed JNTew Section of the Bye-Laws instituting Lady-Associates was rejected by 34 votes to 32. The following proposed Alterations in the Bye-Laws were authorized — (a) unanimously, and (b) by 45 votes to 13 : — (a) That Bye-Law VI, Art. 4 be repealed, and the following substituted : — ' Every Fellow, if elected before the 30th of June, shall be subject to the Contribution for the current year ; but, if elected in November or December, he shall pay no Contribution nor shall he be entitled to receive the Publications for the current year.' .(b) That in Bye-Law XIII, Art. 18 ' and by cheques other Members' be repealed, and the following substituted: — ' and by cheques drawn and signed in such manner as the Council shall direct.' Vol. 63.^ PROCEEDINGS OF THE GEOLOGICAL SOCIETY. lxXVli June 5th, 1907. Sir Archibald Gelkie, D.C.L., Sc.D., Sec.R.S., President, in the Chair. The List of Donations to the Library was read. The Names of certain Fellows of the Society were read out for the first time, in conformity with the Bye-Laws, Sect. VI, Art. 5, in consequence of the Non-Payment of the Arrears of their Con- tributions. The following communications were read : — 1. ' A Marine Fauna in the Basement-Beds of the Bristol Coal- fields.' By Herbert Bolton, F.R.S.E., F.G.S. 2. ' Brachiopod Morphology : Cincta, Eudesia, and the Develop- ment of Bibs.' By S. S. Buckman, F.G.S. The following specimens and maps were exhibited : — Marine fossils from the basement-beds of the Bristol Coalfield, exhibited by H. Bolton, Esq., F.R.S.E., F.G.S., in illustration of his paper. Thirteen sheets of the 6-inch Geological-Survey Map of Scotland : Edinburghshire, presented by the Director of H.M. Geological Survey. June 19th, 1907. Aubrey Strahan, Sc.D., F.R.S., Vice-President, in the Chair. Percy George Hammall Boswell, 359 Woodbridge Road, Ipswich ; Thomas Owen Bosworth, B.A., St. John's College, Cambridge ; Robert John Browne, M.I.M.E., Eastern Coal Co. Ltd., Jharia (E. I. R.), Bengal ; James William Dunn, 10 Addingham Road, Mossley Hill, Liverpool ; G. B. Hill, 370 Gillott Road, Edgbaston, Birmingham; Benjamin Morgan, B.Sc, 115 Brondesbury Road, Queen's Park, N.W. ; Frederick William Smith, Duart, Wotton Without, Gloucester ; James Allan Thomson, B.A. (Oxon.), B.Sc. (N.Z.), University Museum, Oxford ; Ernest W. Vredenburg, Assoc. R.C.S., Geological Survey of India, Calcutta ; and Leonard Johnston Wills, B.A., The Gables, Barnt Green, near Birmingham, were elected Fellows of the Society. The List of Donations to the Library was read. The Names of certain Fellows of the Society were read out for the second time, in conformity with the Bye-Laws, Sect. VI. Art. 5, in consequence of the Non-Payment of the Arrears of their Con- tributions. vol. lxiii. h lxXViii PKOCEEDIXGS OF THE GEOLOGICAL SOCIETY. [Aug. IQO7. The following communications were read : — 1. 'The Inferior Oolite and Contiguous Deposits of the Bath- Doulting District.' By Linsdall Richardson, F.G.S. 2. ' The Inferior Oolite and Contiguous Deposits of the District between the Rissingtons and Burford.' By Linsdall Richardson, F.G.S. 3. ' The Flora of the Inferior Oolite of Brora (Sutherland).' By Miss M. C. Stopes, D.Sc, Ph.D. (Communicated by Prof. J". W. Judd, C.B., F.R.S., F.G.S.) 4. ' The Constitution of the Interior of the Earth as revealed by Earthquakes (Second Communication) : Some Xew Light on the Origin of the Oceans.' By Richard Dixon Oldham, F.G.S. 5. ' The Swansea Earthquake of June 27th, 1906.' By Charles Davison, Sc.D., E.G.S. 6. < The Ochil Earthquakes of September 1900 to April 1907/ By Charles Davison, Sc.D., F.G.S. Fossil plants and lantern-slides were exhibited by Miss M. C. Stopes, D.Sc, Ph.D., in illustration of her paper. Vol. 63. j FINANCIAL REPOBT. XXXvii Year ended December 81st } 1000. PAYMENTS. By House-Expenditure: £ s. d. £ $. d. Taxes ... 15 0 Fire-insurance 15 0 0 Electric Lighting and Maintenance 49 3 4 Gas 13 16 2 Fuel 33 9 3 Furniture and Repairs 23 1 3 House-Repairs and Maintenance 5 1 5 Annual Cleaning 9 16 6 Tea at Meetings 22 2 6 Washing and Sundry Expenses 33 16 0 206 1 5 „ Salaries and Wages : Assistant-Secretary 350 0 0 ,, half Premium Life-insurance... 10 15 0 Assistant-Librarian 150 0 0 Assistant-Clerk 150 0 0 Junior Assistant 80 0 0 House-Porter and Upper Housemaid 95 5 3 Under Housemaid 47 18 0 Charwoman and Occasional Assistance 7 19 0 Accountants' Fee 10 10 0 902 7 3 „ Office-Expenditure: Stationery 19 16 10 Miscellaneous Printing 70 19 11 Postages and Sundry Expenses 71 9 10 Murchison and Lyeil Medals 11 2 0 173 8 7 ,, Library (Books and Binding) 210 9 5 ,, Library-Catalogue : Cabinets 64 0 0 Cards 14 14 4 Compilation , 50 0 0 128 14 4 ,, Publications: Quarterly Journal, Vols, i-lxi, Commission on Sale thereof 9 19 10 Quarterly Journal, Vol. lxii, Commission on Sale thereof 3 3 9 Paper, Printing, and Illustrations 1009 15 6 Postage on Journal, Addressing, etc 102 6 6 Record of Geological Literature 140 1 0 List of Fellows 35 2 0 Abstracts, including Postage Ill 10 1 1411 18 8 ,, Balance in the hands of the Bankers at December 31st, 1906 214 10 3 „ Balance in the hands of the Clerk at December 31st, 1906 Ill 4 216 1 7 We have compared this Statement with the Books and Accounts presented to us, and find them to agree. ARTHUR W. STIFFE, { j r, 0. FOX STRANG WATS, M«**™- £3249 1 3 HORACE W. MONCKTON, Treasurer. January 2oth, 1907. vol. lxiii. d Lib rH r" *5 . <5J ^> co ■5 4 - 1 ■KB O 3J so Q O © S o > ce ■SCO ^* co coh< i—l ^ S c=£H E S ^ O © fl a 2.S o * hh -a « CO aJ— < ffl ffl r^tu 32 rH a lilt o „ EH - =rt O O CO CM 1 GC NCJIO 1 os 1 t— 1 o Xi-i 1— CM CM 8 1 «rt o -1 o o ~ ci 5 33 > 5- r^J o £ F "3 . -< SB & o o o < Ph © co _ej ' © ^ pq © - •^ 2 ^ © ^•"3 a^ 3^ S ^3 P ^* CM o o x E o 15 O < Ph c/L' pp jo x ^ ^ ?, SI | CO «H — ~ 5 *S S2 « ^ co co co O ^* »-0 CO O .-s O :1 CO .S o ~ 3 a H §^ s © «i>> >sj o a ^ 13 © w a o a ■^ © S ^"^ ^ a a Sac 2 2 © § PQP P4 " CO >>» l~" < --So ^ a .« 'M 5 -i.*;^ ©" pqp K O o I P Eh © co.SP ^ a § © Q. © a © risi oa 3 e ^ 05 ^"t © a x^ S o EH CO Ttf os co i—i aTtMO pq -H r^ r— 1 ^ O cm ■ ■»■> _- < H s^ o Ci Co** M ^ H t-H i— i i2 cj cq oo cd 3*1 h? • a <; • r-i 3 a> o CD t-5 o 3 CD .2 o 1-1 5 1o Ph ^ & § fl ^ U cS CD CD 56 _i "t^ r-1 "S — ' •H Ii y )> A PH CD .2 O OS h3 «Ph r-t CD CO ^-^ c?> hS4" c3 CD p a a M f>-j H 9 °~ f^I00 s I -+-> -^ C- 1 •« i a. 2^ JH Jj (t rH Oi CD S O >— ! r- Bank s Inco 8 per Meda Incon CD * £" -4-t -5^-S o ° -*-3 -r, c ^ a alance ividen £700 eceive epayn r pp p - * H h1 H ^ i Z o o o • By Cost of Medal ] f Award to the Medallist ' 25 0 „ First Award from the Balance of the Fund .. Second Award from the Balance of the Fund „ Balance at the Bankers' at December 31st, 1906 Barlow-Jameson Fund d.\ By Award Trust-Account. Receipts. £ To Balance at the Bankers' at January 1st, 1906 30 4 3 Dividends (less Income-Tax) on the Fund invested in £468 Great Northern Railway 3 per cent. Debenture- „ Stock 13 6 10 „ Repayment of Income-Tax (1 year) 14 0 Payments. Balance at the Bankers' at December 31st' 1906 Receipts. To Bnlnnce nt the Banters' nt January 1st, 1000 ,. Dividends (less Income-Tax) on the Fund in £210 Cardiff' 3 per cent. Stock ,, Repayment of Income-Tax (1 y-ear) £9 12 2 ' Geological Relief- F Receipts. £ s f; To Balance at the Bankers' at January 1st, 1906 22 10 11 „ Dividends (less Income-Tax) on the Fund invested in £139 3s. 7(7. India 3 per cent. Stock 3 19 4 YV. Whitaker 6 13 0 Trust- Account. Payukkts. By Balance at the Bankers' at December !3lst, 1901'. Trust-Account. Payments. !y Grant. , Balance at the Bankers' at De iber31st, 1906 Donation from Mr „ Bepaymeut of Income-Tax (1 year) £33 Receipts. To Balance at the Bankers' at January 1st, 1906 ., Dividends (less Ineome-Tax) on the Fund invested ... ±700 India 3 per cent. Stock ]9 i ,, Deceived from Medallist ,, Repayment of Income- Tax (1 year) Trust-Accoun'j ' Prestwich Trust-Fund. £ s. d. | !4 3 11 By Part Gost of Die Payments. Wyon, Medal Award ' .' ' , ]~ 0 ° „ Purchase of £12 11a. 5d. India 3 per cent." Stool 1 0 9 1 >} Balance at the Bankers' at December 31st, 1906 . 22 3 0 . 22 3 0 . 53 12 10 £123 19 10 £ i. d. 2 2 0 31 5 9 10 'Daniel-Pidgeon Fund Receipts. £ To Balance at the Bankers' at January 1st, 1906 ... 10 „ Dividends (less Income-Tax) on the Fund invested i,', £1019 U 2tf. Bristol Corporation 3 per cent. Stock. 29 o ]0 „ Repayment oi Income-Tax (1 year) j 10 « s. d. 0 11 Trust-Account. Payments. By Award „ Balance at the Bankers' at December 31-1. 1906 We have compared this Statement with the Books and Accounts presented to us, and find then, to agree HORACE W. MONCKTON, Treasure, A|;T1|ui; w ^ January 25th, 1907. C. FOX' STKANI ; W.A VS, £ *. d. 30 1 1 I 16 0 J I xl PEOCEEDISGS OF THE GEOLOGICAL SOCIETY. [May I907, Statement relating to the Society's Property : December 31st, 1906. £ s. d. £ s. d* Balance in the Bankers' hands, December 31st, 1906: On Current Account 214 10 3 Balance in the Clerk's hands. December 81st, 190G 111 4 216 1 7 Due from Messrs. Longmans & Co., on account of Quarterly Journal, Vol. LXII, etc 81 8 5 Arrears of Admission-Fees 75 12 0 Arrears of Annual Contributions 205 19 0 281 11 0 £579 1 0 Funded Property, at cost price : — £2500 India 3 per cent. Stock 2623 19 0 £300 London, Brighton, & South Coast'Rail- way 5 per cent. Consolidated Preference- Stock 502 15 3 £2250 London & North- Western Railway 4 per cent. Preference-Stock 2898 10 6 £2800 London & South- Western Railway 4 per cent. Preference-Stock 3607 7 6 £2072 Midland Railway 2| per cent. Per- petual Preference-Stock 1850 19 6 £267 6s. 7d. Natal 3 per cent. Stock 250 0 0 11,733 11 \N.B. — The above amount does not include the value of the Collections, Library, Furniture, and Stock of unsold Publications.] HORACE W. MONCKTON, Treasurer January 25th, 1907. Vol. 6^.~] ANNIVERSARY MEETING WOLLASTON MEDAL. xli Award of the Wollaston Medal. In presenting the Wollaston Medal to Prof. William Johnson Sollas, F.R.S., the President addressed him as follows : — Professor Sollas, — f* The Council of the Geological Society has this year awarded the Wollaston Medal to you, in recognition of the value of your varied and prolonged contributions to the development of Geology. There is hardly a department of our science into which you have not carried the light and impulse of your brilliant and versatile genius. You have united in no ordinary way the qualifications of an accomplished petrographer, an excellent palaeontologist, an able stratigrapher, and a philosophical mineralogist, and to this wide range of accomplishment you have added an originality and inventiveness which have introduced notable improvements into the processes of research. I regard it as a special honour and pleasure that it has fallen to me to be the medium of presenting this medal to you. You have long been one of my most esteemed friends, and I trust that I may be allowed, even in this public place, to add my own personal felicitations to those of, I am sure, all the Fellows of the Society that the highest honour which we have to bestow should now be conferred upon you. If the award is a recognition of past services in the cause of our beloved science, you will, we hope, accept it as no less an augury that we look forward with confidence to much, fresh work from your hands in the future. We hope to see a flourishing School of Geology growing up at Oxford under your fostering care, and to welcome from you in the years to come many memoirs, not less suggestive and important than those with which you have already enriched the literature of geology. Prof. Sollas, in reply, said : — Mr. President, — I deeply appreciate the honour 'conferred upon me by the Council; and if, by any means, I could be reconciled to the sense of my own insignificance, awakened by the recollection of the many illustrious names that have preceded me in this place before the President's Chair, it would be by your kind, I fear too kind, words, and the favour with which they have been received by the Fellows of the Society. Xlii PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [May I907,, It is by no merit of mine that I am a lover, an ardent lover oil Geology, for I feel, perhaps with a lover's partiality, that our' gracious mistress, bountiful as she is fair, requires only to be seen as she truly is to captivate at once all hearts. I have found in her service a perpetual delight, and if your kind wishes should be fulfilled shall ever continue to do so, for she repays our constancy with a variety that never stales. I know how close is the interest taken by you, Sir, in the cause of Geology at Oxford, it has been a frequent source of encourage- ment to me, and the hope you now express is that which lies nearest to my own heart. As a teacher I increasingly feel with advancing years how great is my debt to my masters, Huxley, Ramsay, Bonney, and, Sir, yourself, for I have been a diligent student of your teaching ever since the appearance of ' The Scenery of Scotland ' in 1865. But to you, Sir, and to my revered tutor, I am indebted not only for direct instruction, but for the light of example, the privilege and stimulus of friendship, and indeed for those very opportunities by which I stand here to-day. I count it therefore not the least of my good fortune that I receive the, Wollaston Medal from your hands. AwAED OF THE MURCHISON MEDAL. The rEESiDENT then presented the Murchison Medal to Mr. Aleeei> Haekee, F.R.S., addressing him in the following words: — Mr. Haekee, — The Murchison Medal has been assigned to you as a testimony; of the Council's appreciation of the importance of your contribu- tions to Petrographical and Structural Geology. You had already distinguished yourself by your studies in Cleavage, by the zeal and success with which you had thrown yourself into the pursuit of petrographical research along those modern paths in which this department of our science has been so transformed and enlarged, and lastly by the skill which you had shown in the field-investiga- tion of the ancient igneous rocks of North Wales and of part of the Lake District. With this reputation already established and yearly growing, you were induced, at my request, to enter the Geological Survey. Although the circumstances under which you Yol. 6^.~] ANNIVERSARY MEETING MURCHISON MEDAL. xKii joined that service formed a new departure in its usages, I have always felt that on no part of my long connexion with the Survey could I look back with more satisfaction than on the arrangements which enabled us to secure your services. You speedily acquired the skill of a practised surveyor, and among the hills of Skye and Rum you had an opportunity of mapping some of the most complicated and deeply-interesting pieces of volcanic geology in this country. Having had from time to time opportunities of visiting you on the ground, I can bear witness both to the bodily vigour and endurance and to the geological enthusiasm and insight with which you climbed crags and peaks on which no geologist had set foot before you. The maps and memoirs which you have produced of these portions of the Inner Hebrides will always remain as a monument of your prowess as a field-geologist and petrographer. In handing you this Medal, which bears the honoured name of Murchison, let me wish you, on the part of the Council and of the Society at large, health, leisure, and opportunity, that you may enjoy a long, useful, and distinguished career. Mr. Harker replied as follows : — Mr. President, — I wish, in response to what you have said, to express my very sincere acknowledgments to the Council for the distinction which they have conferred upon me. The pleasure with which I first received news of this honour has since been enhanced by the knowledge that my gratification is shared by friends and fellow- workers, and it is now crowned by the graceful words with which you have accompanied the presentation. In my work in Skye, to which you have made kind reference, it has been my privilege to tread ground rendered classic by the labours of some of the masters of our science ; and I hold it peculiarly appropriate, as it is eminently pleasing to myself, that this mark of the generous appreciation of the Council should be conveyed by one of those my predecessors — by one, moreover, who first directed my steps in a field which he had already made his own. That the work has been a labour of love I need not say to any geologist who has felt the fascination of the West Highlands — least of all, Sir, to yourself. Where the work is its own reward, so flattering a recognition as this might perhaps be deemed an unearned addition. I take leave, however, to regard it as in some Xliv PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May I907, part an encouragement for the future, and with it I must accept the responsibility of justifying to the best of my powers the choice of the Council. To me, finally, this Medal will be in a special sense a memento of the ten }*ears which I spent so pleasantly on the Geological Suryey of Scotland : not only because the Medal itself was founded by a former Chief of the Surrey, and comes to me from the hand of one of his successors ; but also because this Award adds my name to a list which includes those of yourself, who, as Director-General, despatched me to the island which you knew so well ; of Dr. Home, head of the Scottish branch, my constant friend and counsellor ; of Dr. Peach, my immediate superior on the Suryey ; and (last year) of Mr. Clough, the colleague who initiated me into the craft of geological surveying, setting a standard to which, I fear, his pupil has not often attained. A WARD OP THE LtELL MEDAL. In handing the Lyell Medal, awarded to Dr. Joseph Frederick Whiteaves, F.R.S.Can., to Lord Strathcoxa, for transmission to the recipient, the President addressed him as follows : — Lord Strathcoxa, — The Lyell Medal of the Geological Society is this year awarded to Dr. Joseph Frederick TThiteaves, as a mark of the Council's appreciation of his prolonged and valuable contributions to the Geology and Palaeontology of Canada. As a young man, before he settled in the Xew World, he had already shown his scientific bent by several published papers on the land and freshwater mollusea and on the fossils of some of the Oolitic formations of Oxfordshire. Half a century ago he transferred his home and his geological energy to Canada, and from that time until now his scientific activity has known no pause. In 1876 he was appointed to succeed the illustrious Billings as Palaeontologist to the Geological Survey of Canada. In that official capacity he found increased opportunity of studying the fossils that were brought to the Survey Museum from the eastern provinces, from Manitoba, and from the far shores of the Pacific Ocean. Thus every fossiliferous formation in the wide Dominion has come under his review, and he has described many new forms in various grades of the animal kingdom. Following Yol. 6^.~] ANNIVERSARY MEETING BIGSBY MEDAL. xlv the path so admirably opened up by bis predecessor, Dr. Whiteaves has amply sustained the scientific reputation of the Canadian Geological Survey, and has made solid contributions of great value to Palaeontology. In requesting you, Lord Strathcona, as High Commissioner for Canada, to be so good as to transmit this Medal and its accompany- ing cheque to our esteemed colleague in Ottawa, I would beg you at the same time to assure him that the Geological Societ}- values his services to our science, takes an interest in his welfare, and sends its cordial wishes for the continued prosperity of the great scientific institution in which he has laboured so long, and to the renown of which he has so greatly contributed. Lord Strathcona, in reply, expressed the pride and pleasure which he felt in receiving the medal on behalf of a palaeontologist, the great value of whose work had been known to him for many years. He recalled the inception of the Canadian Geological Survey under Sir William Logan, and remarked that, in showing its appreciation of the merits of Dr. Whiteaves, one of the most indefatigable workers on that Survey, the Council of the Society had done honour to the Survey and to Canada. Award of the Bigsby Medal. The President then handed the Bigsby Medal, awarded to Mr. Arthur William Rogers, M.A., to Mr. G. W. Lampllgh: for transmission to the recipient, addressing him as follows : — Mr. Lamfltjgh, — The Bigsby Medal has been adjudicated by the Council to Mr. A. W. Rogers, in appreciation of his important labours in South African Geology. For more than ten years he has been at work in Cape Colony ; not infrequently under difficulties which, in older countries like our own, can hardly be realized. His nume- rous reports, whether prepared by himself alone or conjointly with his colleagues on the Geological Commission, and published in the -Commission's annual volumes, have materially increased our know- ledge of the geological structure of the southern part of the African continent. Besides these official memoirs, he has published alone, and also in conjunction with his able colleague, Prof. E. H. L. Schwarz, xlvi PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [May I907,. in the ' Transactions of ne South African Philosophical Society,*" some important papers in which striking evidence has been brought forward in favour of old glaciation during more than one geological period in South Africa. His volume published in London two- years ago, under the title of 'An Introduction to the Geology of Cape Colony,' reveals the patient and cautious character of his work, and shows how firmly and quietly the foundations of our knowledge of' the geological history of that interesting region are being laid. This Medal is always given to one who is not more than 45 years of age and thus, to use the words of its venerable founder, 'probably not too old for further work, and not too young to have done much/ In asking you to be so good as to transmit this Award to Mr. Sogers, I should be glad if you would accompany it with an expression of our good wishes for himself, and of our continued interest in the important and useful work of the Geological Survey which he so- ably superintends. Mr. La3iplegh, in reply, said : — Mr. President,— It gives me deep satisfaction to receive this Medal on behalf of Mr. Pogers, for, like all the geologists who took part in the visit of the British Association to South Africa, I have learned to appreciate very highly the results of his work and to admire the patient sincerity of the worker. Mr. Rogers has sent a letter which, Sir, with your permission, I will read : — ' Geological Commission, South African Museum, Cape Town, Jan. loth, 1907- ' To the Cotjxcix of the Geological Society of London. ' Gentlemen,— 'I thank you most heartily for the honour which you have done me by the award of the Bigsbjr Medal. I take it as a recognition that the geological surve}' of" this Colony has been carried out on sound lines, and as an expression of your hope that the work will continue. ' The official geologists of the present generation in South Africa are more fortunate than their predecessors in having instructions which allow them to work steadily at the geological structure of the country, unhampered by frequent orders to^ investigate some local details of passing interest. Thus a firm foundation is being- laid for future work, both scientific and economic. In Cape Colony, which was the first of the South African countries to institute a systematic survey, the Geological Commissioners have pursued this policy from the commencement of the survey under their control ; 1113' predecessor in charge of the work, Dr. G. S. Corstorphine,. always kept this end in view, and I have done the same. ' In examining the manuscript map (dated 1859) and sections made by the first Vol. 6$.~] ANNIVERSARY MEETING WOLLASION ErJND. xlvil official geologist at the Cape, Andrew Wyley, once a Fellow of this Society, it is impossible not to perceive that, had he been allowed to continue his work, the geology of the Colony would long ago have been well known, even as regards those parts where to-daj" the broad outlines are still uncertain. ' Circumstances prevent the establishment of a lavishly-equipped Survey in this Colony, and there are man}' problems which have to be left almost untouched because their investigation requires too detailed work ; but your award will make Cape geologists feel that their efforts are warmly appreciated, and I believe that my colleagues past and present will share mj- gratification. ' For nryself, I must say that your generous gift will always urge me to do better work, and my onl}- regret is that I am unable to receive the Medal personally from a man whose writings have been a constant source of instruction and pleasure to me ever since Geology began to be the great interest of my life. ' Believe me, ' Yours faithfully, 'Arthur W. Rogers." AWARD OE THE WoLL ASTON DoNATION-FuND. Iii handing the Balance of the Proceeds of the Wollaston Donation-Fund, awarded to Dr. Arthur Vaughan, B.A., to Prof. W, W. Watts, for transmission to the recipient, the President addressed him in the following words : — Professor Watts, — The Balance of the Proceeds of the Wollaston Donation-Fund has been assigned to Dr. A. Vaughan, as a mark of the Council's appre- ciation of the excellence of his contributions to Geologj-, and in particular of his application of the zonal method of stratigraphical classification to the Carboniferous Limestone of this country. I had often wondered why this method, which was so successfully adopted many years ago for the corresponding portion of the Carboniferous system of Belgium, should never have been similarly applied to our own great Limestone-deposit. Dr. Vaughan has now demonstrated, by a careful study of the corals and the brachiopods, how completely it is available here, and the basis of investigation which he has laid so firmly in the Bristol region will doubtless prove to be one upon which the stratigraphy of the Carboniferous Limestone throughout the rest of the British Isles may be satis- factorily worked out. When you transmit to him this Award, will you assure him that the Society looks forward with much interest to the continuation of his important labours ? xlviii PBOCEEDIXGS OF THE GEOLOGICAL SOCIETV. [May I907, AwAED OP THE MlJECHISOX GEOLOGICAL FfXD. The Pbesidext then presented the Balance of the Proceeds of the Murchison Geological Fund to Dr. Felix Oswald, addressing him as follows : — Dr. Oswald, — The Council has awarded to you the Balance of the Proceeds of the Murchison Geological Fund, in recognition of the value of your contributions to our knowledge of the Geology of Armenia. The remarkable volume which you have published on this subject affords ample evidence of your keen powers of observation and of the indomitable courage with which you have done pioneer-work in a little-known country and with which, also, you have laid your results before the world. Your treatise is, in one respect, probably unique in geological literature. To surmount the difficulties presented by the expense of publication, you purchased a hand-press, learned the art of type- setting, and laboriously printed off the whole book, page by page, with your own hand, while the numerous sections, maps, and plates of fossils were likewise drawn, reproduced, coloured, and printed off by yourself. The volume is dedicated to your wife, who will share your pleasure at this recognition of your labours, and to whom with yourself I desire to convey the good wishes of the Geological Society. AWAEDS FBOM THE LVELL GEOLOGICAL FlJXD. In presenting a moiety of the Balance of the Proceeds of the Lyell Geological Fund to Mr. Thomas Ceosbee Caxteill, B.Sc, the Pbesidext addressed him in the following words : — 'O Mr. Caxteill, — The Council has this year awarded to you a moiety of the Balance of the Lyell Geological Fund, in recognition of the quality of your contributions to Geology, more particularly in relation to the strati- graphy of the formations from the base of the Lias down into the older Palceozoic rocks. Your early paper on Wyre Forest afforded good promise of your future success. Since it appeared you have served Yol. 6$.~] ANNIVERSARY MEETING LYELL FUND. xlix for upwards of ten years oh the Geological Survey, where, as I can personally testify, your work has been characterized by remarkable carefulness and precision. It is to me a great gratification to hand this Award to a former Survey colleague, and to wish you continued activity and success in your career. The President then presented the other moiety of the Balance of the Proceeds of the Lyell Geological Fund to Mr. Thomas Sheppard, E.G.S., addressing him as follows : — Mr. Sheppard, — The other moiety of the Balance of the Lyell Geological Eund has been assigned by the Council to you, in acknowledgment of the useful additions made by you to our knowledge of the Pleistocene Geology of East Yorkshire ; of the value of your bibliographical work and your labours in the Hull ALuseum ; and of the excellence of your volume on ' Geological Rambles in East Yorkshire,' which contains much information presented by you in a popular and attractive form. .PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [May I907, THE ANNIVERSARY ADDRESS OF THE PRESIDENT, Sie Archibald Geikie, D.C.L., LL.D., Sc.D., Sec.R.S. Eor many years past it has been usual for the President, on this -Anniversary occasion, to prepare an Address dealing with some ■special subject in geology or with the work of the Society during the past Session. We meet to-day under exceptional circum- stances, which may perhaps warrant some departure from the customary practice. The Society has now attained its hundredth year, and our proceedings during the present Session will naturally have reference to that interesting event in our history. When last February you did me the great and exceptional honour of electing me to fill this Chair for the second time, it was with tacit reference to what should be done in the way of celebrating our centenary. The knowledge that this was so greatly touched me. To be chosen as the spokesman of the oldest geological Society in the world on the occasion of its first great jubilee is indeed a distinction of no common kind. It was with a deep sense of your kindness and my own respon- sibility that I begau some time ago to consider what subject would be specially appropriate, as the selected subject ought certainly to be, to the circumstances in Avhich we this year hold our Anniversary Meeting. I was eventually led to debate in my own mind whether such an address would be more fittingly given now or be held over until the formal celebration of our centenary some months later. Further reflection convinced me that, as I could hardly see my way to prepare, and to inflict on the Society, two addresses in the same year, and as one would certainly be required, in some form, at our coming festival, it would be best to reserve for that occasion what, under ordinary circumstances, would have been spoken now. With regard to the arrangements for the celebration of our centenary, I should like to take this opportunity of making a few remarks to the Society. The Council has appointed a Committee to frame and carry out these arrangements, and this Committee has already begun its duties. Enquiry has shown that the last week in the month of September appears to be, on the whole, the time which will be most generally convenient to Fellows and guests in this country and to visitors from abroad. It is therefore intended that the celebration shall take place at that time. Every Vol. S^.'] ANNIVERSARY ADDRESS OE THE PRESIDENT. H Fellow of the Society will, of course, receive due notice, as well as ■a detailed statement of the arrangements when these have been finally settled. Invitations to attend the meetings will be imme- diately sent out to all our Foreign Members and Foreign Corre- spondents. Geological Societies, Geological Surveys, and learned institutions which have a geological side will be asked to send delegates. Personal invitations will also be addressed to geologists of note in the Old and the xSew World who may not be already enrolled in our foreign lists. It is hoped that to these various invitations there will be a friendly response, either by personal representation or in writing. We may not impossibly be privileged to see a larger company of geologists assembled together here next September than has ever been gathered together in this country before. It is thought that the official programme may extend over three days in London. The arrangements for each of these three days are under consideration, but I may mention now that I propose to give my postponed Address as the piece de resistance of one of the forenoon or afternoon meetings. In that address I shall offer a sketch of the state of geological science outside of Britain at the time when our Society was founded, and indicate the external influences that affected its start. By this choice of a subject I hope to interest our foreign friends, while at the same time in- viting our own Fellows into a domain of the history of science which is perhaps less familiar than it deserves to be. The chronicle of the Society itself during the first hundred years of its existence has been carefully and fully compiled from all available sources by our colleague, Mr. Horace B. Woodward. His volume is now at the printers', and will be in the hands of Fellows in the course of the summer. Excursions to places of geological note in this country will probably be arranged, some to precede and others to follow the meeting here. The various museums and places of interest in London will, of course, be shown to our visitors ; and there will doubtless be no lack of public and private hospitality. It is anti- cipated that the Universities of Oxford and Cambridge will receive our foreign friends. But the details of these various arrangements have still to be worked out. From this bright anticipation of festivities in the near future I must now regretfully turn to the moarnful duty which devolves Hi pkoceeui^gs or the geological society. [May 1907,. upon the President at our Anniversary to record the losses "which the Society and geology at large have sustained during the past twelve months from the thinning of our ranks hy death. By the death of Eugene Bexeviee, the Society loses one of its most esteemed Foreign Members, and geology one of the veterans of last century who notably contributed to the advancement of the science. Born at Lausanne on March 25th, 1831, he remained not only true to his country but faithful also to his native city, for it was there that he spent a long, active, and honoured life, which was sadly and suddenly closed by a fatal accident on the 4th of last May. After his earty education in Switzerland, Benevier was boarded by his father at Stuttgart, where he attended the Polytechnic School, and where he received the impulse towards scientific pursuits which soon became the paramount interest of his career. He had already begun to collect minerals, and he now made the acquaintance of his fellow-student Oppel, who, as an earnest of his future distinction in palasontological research, was already in the habit of gathering fossils. The two young naturalists made ex- changes of their little duplicates, and doubtless by their influence on each other determined their respective vocations in life. There appears at least to be little doubt that, when he left Stuttgart, Benevier's bent towards science was already so strong as to over- master every other tendency. In 1848, when only 17 years old, he climbed among the cliffs of the Diablerets in search of fossils. He seems to have remained about three years at Stuttgart. At the end of that time, and before he was twenty, he felt himself strong enough to venture into the arena of geological authorship by com- municating his first scientific paper to the Societe Yaudoise des Sciences Xaturelles. In this maiden effort, which was an attempt to determine the place of the freshwater molasse in the series of the Tertiary formations, and also in his other early writings, he struck what proved to be the keynote of all his scientific energies, which was a combination of stratigraphical and palgeontological research directed towards the determination of the true order and succession of the stratified rocks. This intimate combination was employed by him with the object of tracing out the history of geographical change and the progress of organic life, in the first instance upon the site of his own beloved Switzerland, and then over the whole surface of the globe. Vol. 6^.~] ANNIVERSARY ADDRESS OF THE PRESIDENT. liii The criticisms made on his first essay taught him that further study was necessary. He therefore in 1851 betook himself to Geneva, in order to attend the instruction given there by the illus- trious palasontologist, P. J. Pictet. Prom that centre he devoted himself to the task of working out the succession of formations in the district of the Perte du Rhone, and, when only two-and- twenty, produced his now famous memoir on that subject. With the view of still further advancing his scientific training he went in 1854 to Paris, in order to place himself under the teaching of Hebert. While in the French capital he wrote, in conjunction with his master, a memoir in which were described the Num- mulitic fossils from his haunts among the Diablerets and other places in Savoy. This paper was read to the Geological Society of Prance in June 1854. Prom Prance he crossed over to England, where he spent some time in studying more especially the fossils of the Lower Greensand and the fauna of Blackdown. This visit gave him a lifelong personal interest in Britain and British geologists. Returning to Lausanne in 1855, he found that his reputation as a promising young man of science had preceded him. In the following year he was appointed to a post in the Academy of Lausanne. At first he gave a course of lectures on zoology, but early in November 1859 he exchanged that subject for geology, which then included physical geography, stratigraphy, palaeontology, mineralogy, and petrography. After 1863 his academic range of subjects was fortunately curtailed ; Mineralogy and Palaeontology were made into distinct Chairs, and Petrography was afterwards also separated. In 1890 the Academy having been transformed into a University, Renevier became Professor of Geology and Palaeontology. Thus for half a century he continued to have charge of the instruction in his own favourite departments of science. He was not a lecturer who by the eloquence and impulse of his language fired his students with enthusiasm. But he gained their attention and sympathy in another way. They could not but be impressed with his whole- hearted devotion to his subject, his eagerness to communicate his knowledge, his indomitable persevering application to the problems of which he sought the solution. They were won over, too, by his personal charm, by his patience, his gentleness, his helpfulness, and by the good humour which brightened all his relations with them. He thus became a living force in the educational progress of his country. vol. lxiii. e Hv PEOCEEDIXGS OF THE GEOLOGICAL SOCIETY. [^lay I907, His success as a teacher depended also, in do small degree, upon the amount and quality of his work as an original and unwearied investigator, and the recognition which this work met with, not only in Switzerland but throughout the scientific world. The fossili- ferous rocks of his native land had early fascinated him, and he consecrated all his mental and bodily energies to their patient study. In his young days, after returning to Lausanne, he would in summer make his way into the Alps to begin there those researches which, late in life, he brought to so excellent a conclusion. There were then still living some of the survivors of the heroic age of geology, whom he was privileged to meet. He used to tell of his acquaintance with Jean de Charpentier, and of the great men whom he had heard disputing with that illustrious glacialist over his theoretical views. He was delighted to recount to his students how one day he was scolded by Leopold von Buch for having ventured to offer to that old geological Spartan the loan of an umbrella. Eenevier had great powers of endurance, which stood him in good stead in his mountain-climbing. He is said to have been able to go through a week of excursions, carrying with him for all meals only a box of some kind of peptone and a little bread. And in his unwarmed museum during winter, when everything was frozen hard outside and inside, he would discourse with his usual enthusiasm on the specimens, while to the shivering students it seemed as if he must get his warmth out of his beloved fossils. He was always at his best in the field. There his gaiety and merriment, his fund of anecdote, and his contagious enthusiasm over everything geolo- gical made him a charming associate to his friends and an inspiriting professor to his students. Having begun at an early age to publish the results of his obser- vations, Eenevier continued all through life to pour forth a copious stream of contributions to geological literature. As the Societe Yaudoise has its seat at Lausanne, and publishes summaries of its proceedings, it supplied to the young student and teacher a constant stimulus and companionship in scientific work, while at the same time it provided an opportunity for making the results of his researches known to the geological world outside. Eventually he became the life and soul of that Society, seldom failing to appear at its meetings, and taking the keenest personal interest in its business. Having such a channel of publication open to him in his own Vol. 6$.^\ ANNIVERSARY ADDRESS OE THE PRESIDENT. - lv town, he availed himself of it freely from his youth onwards. The early volumes of the Society's 'Bulletin' are full of short notices or reports by him, referring either to his own work or to that of other observers. In looking through these volumes one may notice the appreciation which he shows of the progress of geology in Britain One of his first papers, for example, read as far back as July 1855 was a sympathetic summary of the memoirs of Daniel Sharpe on the Cleavage and Foliation of the rocks of the North of Scotland, which had appeared in our Quarterly Journal. A few months later he gave an account to the same Society of his studies in the South of England, to which I have already alluded, and he there referred to the collections of Dr. Fitton, the Geological Society, and the Geological Survey, which had been liberally placed at his service, announcing at the same time that he had himself been so diligent in the search for the fossils of the English Lower Greensand and Blackdown Beds that he had been able to form a collection which, in his opinion, was undoubtedly one of the finest after those just mentioned. Renevier's passion for stratigraphy based on the accurate deter- mination of fossils, so prominently manifest in his earliest writings, found abundant expression through his long and strenuous life. I have referred to his quarto memoir on the Perte du Rhone, which, although the work of so young a man, has become a classic in the history of Swiss geology. It may be taken as the type and fore- runner of all his subsequent labours. A trained and able palaeon- tologist, he well knew how to appreciate and enforce the value of the evidence of fossils in every branch of stratigraphical research. He was less interested in the tectonic structure of the Alps than in unravelling the order of succession among the stratified formations of these mountains. He had indeed shown in early life an appre- ciation of the importance of tectonic studies, when he applied the generalizations of Daniel Sharpe to the interpretation of the crushed and contorted rocks of Switzerland. But his relation to this de- partment of geology became rather that of a keen and watchful critic of the opinions of others, than that of an original observer in the same field. He had for many years been engaged in Alpine research, and had his material in great part ready for publication when an affection of the eyes retarded his progress, and became at last so serious that in 1880 he nearly lost his sight. Not until 1890 did his great quarto monograph on the Hautes Alpes Yaudoises appear as one of e2 lvi PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [May I907, the Livraisons of the Geological Commission of Switzerland. This is undoubtedly Renevier's masterpiece. It was the result of more than a quarter of a century of mental and bodily toil, and will remain an imperishable monument of his genius. Xo one can travel over the ground so well described and so admirably illustrated in this lEemoir without a profound admiration for the enthusiasm, endurance, patience, and skill of the kindly and gentle Professor of Geology at Lausanne. Besides his prolonged application to the task of elucidating the stratigraphy of his native country, Eenevier took a wider view of the subject, and devoted himself with great zeal and unwearied persistence to the still more arduous labour of trying to convert the geological world to his views as to the necessity of introducing greater uniformity into the terminology of geology, more especially in the department of stratigraphy. He was the originator and the prime source of the energy of the Committee formed by the Inter- national Geological Congress for the consideration and codification of this subject. The reports of this Committee bear eloquent witness to the amount of time and thought which he bestowed upon them, and the subject with which they deal. His chief con- tribution to this branch of geological literature is his ' Chronographe Geologique/ which, first issued in 1873-7-1, reached its culminating and gigantic proportions in the second edition published in 1896. There is much that is both attractive and suggestive in the orderly method and symmetrical nomenclature embodied in the huge strati- graphical table in this work. Even where we may be reluctant to see time-honoured stratigraphical and other appellations crushed into the Procrustean bed which Eenevier so skilfully prepared for them, we must admit the wisdom of his general aim, and recognize the good service done by him in holding this laudable aim pro- minently and persistently before the geological world for so many years. One of the duties in which he took more especial pleasure at Lausanne was the supervision and enlargement of the Geological Museum. AYith but slender financial resources he succeeded in forming an admirable collection of fossils and minerals. He was practically its founder, and he watched over its welfare and growth as a father over his child. Each year he would issue a little tract giving an account of the progress of the collections, and distribute copies of it among his friends and correspondents abroad, who were always glad to receive these friendly tokens of the ceaseless activity Tol. 6^.~\ ANNIVERSARY ADDRESS OF THE PRESIDENT. Mi of the Nestor of Swiss geologists. In spite of the insufficient space available for the exhibition of his constantly increasing collection, he had succeeded in making the museum an admirable educational institution. The same love of logical order and symmetry which impelled him to seek the unification of geological nomenclature reigned over all the cases and galleries of his museum. Had he lived a little longer, he would have had the joy of seeing his collections moved into the more spacious quarters designed for them in the University buildings. With every department of scientific enterprise in Switzerland Renevier s}-mpathized, and where possible he took his share of the active work. He was the founder of the Swiss Geological Society, and continued to be its President up to the end of his life. He was a member of the Geological Commission, member of the ' Com- mission des Memoires ' of the Societe Helvetique, and President of the Geological Commission of the Simplon Tunnel. His influence was thus strong and wide in his own country, but his powers were not less appreciated abroad. His constant and active participation in the meetings of the International Geological Congress made him personally well-known to many geologists all over the world. It was, therefore, a fitting recognition of his personal charm and scientific achievements when they chose him as their President for the Congress which met at Zurich in 1894. He was elected a Poreign Correspondent of the Geological Society of London in 1877, and a Foreign Member in 1888. This notice of our departed friend would be inexcusably incom- plete, if it made no allusion to the religious side of his nature. He was a sincere and active Christian, who carried his faith into the details of life, and who delighted in every opportunity of doing good. In his religion he showed some of the same marked indi- viduality as in his science, but while simple, reverent, and firm in his own convictions, he was always tolerant towards the opinions of others. Those who were privileged with Renevier's friendship mourn in him the breaking of one of the last links that connect them with the early leaders of geological science, but still more do they grieve for the loss of one for whom they had the strongest regard and affection, and for whose scientific achievements they had a sincere admiration. Their sorrow is aggravated by the reflection that he retained up to the last so much of his characteristic energy and vivacity, that but for a tragic accident they might have enjoyed Mii PEOCEEDIXGS OP THE GEOIOGICAX SOCIEIT. ^ay I907, his companionship for still some years to come. It had been in- tended to celebrate last year the fiftieth anniversary of his academical work, and we can believe that the occasion would have called forth a world-wide expression of appreciation of the extent and value of his geological achievements as teacher and investigator, and of affectionate regard for him as a man. But the weakness of his eyesight seems to have led him to mistake the door of a lift for the exit 01 the house in which he was. He fell to the bottom, and died next dav. TTe can now only look back upon the remembrance of his friendship, and on the bright example which he has left of a life unceasingly and cheerfully devoted to the cause of science and the furtherance of good works. - No more serious blow has for a long time fallen upon the chemical and mineralogical side of geology than that arising from the death of Sameel Lewis Pexeield. the distinguished Professor in the Sheffield Scientific School of Yale. He was born on 16th January, 1856, at Catskill, on the Hudson Paver, where his father was a prominent citizen, engaged in mercantile and shipping business. He studied at Yale University, and. after taking his degree with honours in 1S77. devoted himself to original research in the department of analytical inorganic chemistry. The researches of Prof. Brush and Edward Dana at Branchville (Connecticut), revealing a remarkable assemblage of new minerals, afforded Pen field the opportunity that ultimately settled his future career. The determination of these minerals was entrusted to him. and gave him a keen interest in the chemical problems which their analysis suggested. Although it was from the chemical side that he approached the subject, and though in 1880-81 he spent some time in Germany, under Fittig of Strassburg, in researches among organic compounds, thus enlarging his grasp of both sides of modern chemistry, it was not strictly as a chemist that he was to attain the position to which he rapidly rose in the scientific world. In the autumn of 1SS1 a fortunate opening occurred in the Sheffield Scientific School, when G. W. Hawes was transferred to the National Museum, and Penfield was appointed to the vacancy as Instructor in Mineralogy. From that time he continued to be actively 1 Pur some of the personal details contained in this notice I am indebted to the kindness of my friend Prof. Lngeon, the devoted pupil and successor of Eenevier. Vol. 63.^ ANNIVERSARY ADDEESS OF THE PRESIDENT. llX engaged in teaching and research within the walls of his Alma Mater, becoming Assistant Professor in 1 888, and full Professor in 1893. Having now thrown himself heart and soul into the prosecution of mineralogical work, and finding the need of more familiarity with the modern methods of optical and microscopical research, he returned to Europe for some months in 1884, in order to work in the Heidelberg Laboratory under Prof. Rosenbusch. He thus admirably equipped himself for attacking mineralogical questions from every side, and for training a school of students in the most advanced modern methods of mineralogical research. His kindly, sympathetic nature, combined with his great scientific attainments, made him a remarkably successful teacher. The amount and the quality of his work are alike remarkable. He not only made known the composition and relations of a number of new and interesting minerals, but he was able to throw fresh light on the true chemical constitution and mineralogical affinities of other species which had long been known, and of some which were of familiar occurrence. His analyses of the Branchville minerals led to the recognition of the probable isomorphism of fluorine and hydroxyl which he afterwards completely demonstrated, and thus showed * that the existence of these isomorphous radicals not only explains the structure of many minerals, but that their presence is of the greatest importance in understanding the mode of formation, especially in magmatic processes.' He was not only a chemical analyst of the first order, but was hardly less distinguished as a crystallographer. His ingenuity and skill as a manipulator enabled him to devise and improve methods and instruments of mineral- ogical research. It may be said that, in every department of investigation into which he entered, he left the record of his keen insight, his originality, and his breadth of view. Penfield's claims to a high place in the ranks of modern science were recognized in his lifetime by the various honours conferred upon him by scientific institutions in his own country and abroad. He was elected a Corresponding Member of our Society in 1896. His health had not been good for about three years, but the disease from which he suffered took a sudden unfavourable turn, and carried him off on the 12th of August, 1906.1 1 This is a brief summary of the memoir by Penfield's f riend and colleague, Prof. L. V. Pirsson, of Yale, in the ' American Journal of Science ' for November 1906. lx PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [May I907, Geoege Cheetham Churchill, who died full of years on October 11th, 1906, was the son of a Nottingham manufacturer, and was born in that town on September 25th, 1822. Educated as a solicitor, he was, while still a boy, deeply interested in natural history, especially entomology. In early manhood the experiments, already begun, of Messrs. J. B. Lawes and J. H. Gilbert, attracted him to the subject of land-treatment ; and he gained an intimate friend in Josiah Gilbert, the artist brother of the latter. After his marriage in 1853, Churchill removed to Manchester, and at the end of ten years found himself able to retire from professional work and devote himself wholly to scientific study. His vacations had for some time been occupied by botanical researches, and in 1856 he and Gilbert, accompanied by their wives, obtained, as they tell us, their first glimpses of the Dolomite Mountains. In 1860 Churchill returned to them alone, and the three following summers were spent by the four friends in wandering among the grand and beautiful scenery which that rock affords, from the Rosengarten to the Karawanken Alps. These journeys bore fruit in ' The Dolomite Mountains/ a joint issue, published in 1864, which at once took a high place in Alpine literature, and in that year Churchill was elected a Fellow of this Society. Left a widower in 1866, he settled finally at Clifton in 1869, after his second marriage. That union was a brief one, but in 1873 he again found a sympathetic companion, who survives him. So long as health permitted, he continued his travels in search of plants, especially Alpine, and in later years largely augmented his herbarium by exchange and purchase. That herbarium, containing altogether above 10,000 species, varieties, and hybrids, now belongs, partly by gifts during life, partly by bequest, to the Royal Botanic Gardens, Kew, which he had greatly aided in forming their fine collection of living Alpine plants. Though he never contributed to our Journal, the chapter on the Dolomite Mountains, which Churchill wrote to that volume, shows that he had not only studied, but had also grasped the literature of the subject. In short, he was a first-rate botanist, no mean geologist, and a man of wide general culture.1 John Frederick Blake was, for many years, one of the most familiar figures at our Meetings, where he read papers and where he often took part in the discussions of the papers of others. He was born at Stoke-next-Guildford on April 3rd, 1839 ; and, after an education at Christ's Hospital, London, went to Caius College, 1 This notice has been kindly contributed by Prof. Bonney. Vol. 63.^ ANNIVERSARY ADDRESS OF THE PRESIDENT. lxi Cambridge, where he had a successful career, coming out first in the Natural Science Tripos of 1862, and fifteenth Wrangler. He was a pupil of Sedgwick, and it was not improbably the influence of that great teacher which ultimately determined the line of his favourite pursuits. The son of a clergyman, he himself took holy orders, and held one or two curacies in succession, until, in 1 865, he was appointed Mathematical Master and Assistant Chaplain at St. Peter's School, York, where he continued for nine years. He had early distinguished himself in Mathematics, having carried off the first prize in that subject at Christ's Hospital. His love for science had been growing during his stay at York, and he at last resigned his post there, at the same time relinquishing all clerical work in order to prosecute scieuce as his vocation. Por some years he gave courses of lectures at various institutions and on various subjects. His range of acquirement was wide, and he found oppor- tunities of exercising it. Thus for four years he lectured on Com- parative Anatomy at the Charing Cross Hospital, and during that period he also gave a course of lectures on the same subject at King's College. He united the qualifications, not usually found in the same individual, of accomplishment both on the biological and on the mathematical and physical sides of science. These exceptional claims were recognized in 1880 by his appoint- ment as Professor of Natural Science at University College, Not- tingham, where for eight years he continued to teach and organize his museum. But circumstances arose which made the post no longer agreeable to him, and he then removed to London, where for some years he became a frequent contributor to the ' Geological Magazine ' and our Quarterly Journal. He also started at that time a periodical of his own, called by him ' Annals of Geology,' in which he gave summaries of the more important contributions to geological literature in each year, not unaccompanied with pungent criticisms of them by himself. This work he continued to issue for four years (1890-93), until, from want of adequate support, it was abandoned. In 1895 he was invited to Baroda, to form and arrange the State Museum there. He took occasion when in India to look into the geology of certain tracts, and on his return published papers on some of the geological features of Cutch. Back in London, he plunged once more into the scientific work which had now become so congenial to him. But those who came into most frequent contact with him noticed some diminution of his former energy and vivacity. His wife, the youngest daughter of the Bev. P. F. Haslewood, lxii PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. May I907, Rector of Smarden, Kent, whom he had married in 1886, died shortly after his departure for Baroda, and this bereavement cast a shadow over the rest of his life. Yet he fought, and fought stoutly, for the opinions he held on questions of keen controversy at the time. But he was always a courteous and kindly combatant, for whom even his keenest opponent could not but have a friendly regard. Prof. Blake's numerous contributions to the literature of our science range over an ample field of geological research. Perhaps his best and most enduring stratigraphical work was that which he devoted to the stratigraphy and palaeontology of the English Secondary formations. His papers on the Kimeridge Clay and on the Portland Kocks of England, published in our Quarterly Journal, are excellent examples of his methods of investigation and will always hold their place in the historical development of our knowledge of these important portions of the geological record. His ' Yorkshire Lias/ written in conjunction with Prof. Ealph Tate, and his Memoir on the ' Corallian Ptocks/ which he prepared conjointly with Mr. W. H. Hudleston, are standard treatises on their respective subjects. In further continuation of these earlier studies, he was engaged in his later years in preparing a monograph on the Eauna of the Cornbrash for the Palseontographical Society, of which only the first part has been published. He did not restrict himself, however, to the Mesozoic formations. Some of his most strenuous labour was devoted to the endeavour to work out the structure and relations of the oldest rocks of Xorth Wales. He tried his hand, too, among the most ancient masses of the Xorth-West Highlands. And, although his conclusions on such matters have not always met with general acceptance, they were usually ingenious and worthy of attentive consideration. The Geological Society is indebted to Prof. Blake for the labour which he spent upon the List of type-specimens in the Society's Museum. This list, which was printed and published, forms a valuable palseontologieal record. His various services to science and to the Society have not passed without formal recognition from us. He was elected a Fellow of the Society in 186S. In 1877 the Murchison Eund was awarded to him : in 1895 he received the Lyell Medal, and he has served on the Council. He died in London on the 7th of July last year. Chaeles Eugene de Eaxce, who entered the Society in 1S69, was born on November 22nd. 1847. His parents, who were both Vol. 6$.~] ANNIVERSARY ADDRESS OP THE PRESIDENT. lxiii French, took refuge in England at the time of the Revolution of 1848. He thus became a domiciled Englishman, and was educated at King's College School, London. At the age of one-and-twenty he joined the Geological Survey of England under A. C. Ramsay, shortly after the great enlargement of the staff in 1867. He was employed in the survey of portions of Cheshire, Elintshire, and Lancashire, and he prepared the published descriptions of the tracts which he had examined. In the course of these official duties his attention was particularly called to the importance of geological structure in regard to questions of water-supply. He was the chief motive power in the British Association's Committee on the Circu- lation of Underground Waters, of which he was Secretary. He also took part in the work of the Congresses convened by the Society of Arts in 1878 and 1879 to consider the question of Water-Supply. The contributions made by him to these meetings formed the basis of a volume which he published in 1882, on ' The Water-Supply of England & Wales.' In this useful compilation the details are given of the several river-basins of the Kingdom, including their length, area, population, and geological structure, together with such other information as the author was able to procure bearing on the main purpose of the book. His attention to questions of water-supply led to his obtaining some amount of employment as a consulting geologist on this subject. At last, in 1898, he gave up his appointment in the Geological Survey, and devoted himself to private practice as a mining and water-engineer at Blackpool. But probably in some degree from bad health, aggravated by domestic unhappiness, he seems to have gradually lost touch with science, and to have dropped out of sight of his old friends, who remember him in his earlier years as a versatile and lively companion. He died from the effects of an accident on April 28th, 1906. The name of Robert Phillips Greg, which, appears in our Obituary-list this year, cannot but excite a thrill of surprise in the minds of many geologists and mineralogists of this country who were under the belief that both the authors of the familiar and indispensable ' Manual of the Mineralogy of Great Britain and Ireland ' had long since passed out of the land of the living Mr. Greg was born at Manchester on March 23rd, 1826, and from his boyhood must have been imbued with a sense of the attractive- ness of minerals. His father, an active and successful member of IxiV PROCEEDINGS OF THE GEOLOGICAL SOCIETY. rMay 1907, the commercial community of Manchester, had purchased, as far back as 1835, the famous collection of minerals which had been formed by Thomas Allan, a wealthy banker in Edinburgh, and which had been studied and named by Haidinger, afterwards the illustrious Director of the Geologische Eeichsanstalt of Tienna. This collection must have arrived at the Manchester merchant's home when young Greg was only some nine years of age, and we can believe that he helped to unpack and arrange the specimens. After his education, partly by private tuition and partly at a school in Brighton, he went in 1843 to Edinburgh University. Two years later, he began his training in business, and, on coming of age in 1847, was taken into partnership by his father. But he does not seem to have inherited his father's devotion to mercantile pursuits. He married in 1857 Louisa, daughter of Mr. S. S. Clair of Liverpool, and in 1871 moved to Coles Park, near Bunting- ford, Hertfordshire, a charming rural property which has been in the family for upwards of 120 years. There he lived the peaceful and beneficent life of an active and useful country squire. But the attractions of the Allan Collection were not allowed by him to remain uncared for. On reaching manhood he began to collect minerals for the further enrichment of the cabinet, until he made it the most complete and valuable private assemblage of minerals in the country. In the course of these acquisitions he became acquainted with another enthusiastic collector, Mr. W. G. Lettsom, and their acquaintance led to their conjoint preparation of the ' Manual,' which was published in 1858. Every student of minerals in this country knows the excellence of this work, which, after half a century, has not yet been superseded. In 1S60 the collection, which he had so greatly enriched, was sold to the Trustees of the British Museum. He wrote but little on mine- ralogical subjects, which, during the last eighteen years of his life, were replaced in his attention by meteorites. His chief contri- butions to science are numerous papers on meteors. He wrote also a book on the Comparative Philology of the Old and Xew 'Worlds, which was published in 1893. He became a Fellow of our Society m 1853, and took an active interest in the formation of the Mineralogical Society, of which he was for ten years the treasurer. He died on the 20th of last August, in the 81st year of his age.1 1 For this notice I am mainly indebted to that prepared for the ' Mine- ralogical Magazine ' by Mr. Gr. F. Herbert Smith, who was so good as to supply me with an advance-proof. Vol. 6t,.~\ ANNIVERSARY ADDRESS Of THE PRESIDENT. lxv John George Goodchild, born near Loudon on May 26th, 1844, was for forty years a member of the Geological Survey, in which he had a more varied experience than usually falls to the lot of most members of that organization. Joining the staff in 1867 as one of the young recruits at that time enlisted in the service, he was engaged for some years chiefly in mapping portions of the North- "Western Counties of England, including tracts near the Lake District. Gifted with a keen eye and an ardent imagination, he quickly seized the dominant structural features of a district, and drew his conclusions as to the tectonic relations of the rocks. These were always ingenious and suggestive, though subsequent more prolonged study of the ground by his colleagues might neces- sitate the modification of lines traced by him on the maps. In his earlier years he was an indefatigable hill- climber, but an affection of the heart eventually deprived him of his powers of exertion until, in the end, such duties had to be assigned to him in the head-office as would relieve him from the strain of field-work. For some time he continued at the Jermyn Street Museum, charged with the preparation of maps for the engraver and various kinds of Memoir work. At last in 1889, when the Geological-Survey collections in the Edinburgh Museum had grown so extensive as to require the constant care of a resident keeper, he was transferred to the staff of the Survey in Scotland and placed in charge of these collections. In this new position Goodchild obtained greater scope for his remarkable and versatile powers. He carried out the arrangement of the Survey collections, and subsequently of the Heddle Mineral Cabinet, with admirable order and clearness, so that they have become a most attractive and instructive assemblage of the rocks, minerals, and fossils of Scotland. While still in London, he had given courses of lectures at Toynbee Hall on geological subjects which were much appreciated. His position in Edinburgh afforded him still further and better opportunity of developing this side of his capacity. He became an effective lecturer there, and conducted popular excursions to places of geological interest in the neighbour- hood. His pen was not less active than his lips. He continued to publish a continuous stream of notes and papers on a wide and diversified circle of subjects. His range of acquirement in natural history was considerable. To his knowledge of birds he added the gift of being able to portray them in drawings of extreme accuracy and artistic effect. He became a Fellow of the Geological Society in 1884, and in 1893 received the Wollaston Fund in recognition of the lxvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. T^Iay 1907, value of his work. One of his latest and most important contribu- tions to science was the editing of the two volumes on Scottish Mineralogy left unpublished by the late Prof. Heddle, a task which involved an almost incredible amount of labour. His health had been failing for some time, and at last after a lingering illness he died on the 21st of last February. William Paget Jeevis was born in 1831 in India, where his father was engaged on the Topographical Survey. He was brought to this country in 1842, and attended lectures at the Royal Institu- tion which appear to have stimulated in him a taste for geology and mineralogy. He would seem to have also acquired some practical knowledge of mining at Hayle in Cornwall, and after his father's death in 1857 to have studied at some of the science-classes of the University of Edinburgh. A year or two afterwards he was appointed Curator of the Italian Industrial Museum at Turin, in the foundation and arrangement of which he had been invited to assist. Prom that time he continued to reside in Italy, and to labour incessantly in gathering information regarding the distribu- tion of useful minerals and rocks, first in Tuscany and then all over Italy. He began to publish notes on this subject at least as early as 1860, for a paper on some of the mineral products of Tuscany by him appears in our Quarterly Journal for that year. His writings are partly in English, but eventually for the most part in Italian. His most important work is his ' Tesori Sotterranei dell' Italia,' which appeared in a succession of volumes between the years 1873 and 1889. These are mainly statistical, giving the occurrence and distribution of rocks and minerals in the various provinces, but with occasional passages of more general interest. The four volumes evince enormous labour, and form a useful compendium of inform- ation. Jervis attended various International Exhibitions as one of the representatives of Italy, such as those of London in 1862, Dublin in 1865, and Paris in 1878. For these and his other services to his adopted country he was created a Cavaliere by the King of Italy. . He had been elected an Ordinary Fellow of our Society as far back as 1860. He died at Turin on February 18th, 1906. We have to chronicle this year the death of one of the oldest Fellows of the Society, William Cunnlstgton, who, born in 1S13, died last February at the advanced age of 93. Though he wrote Vol. 6$.~] ANNIVERSARY ADDRESS OF THE PRESIDENT. lxvii and published a few papers on geological subjects, two of which appeared in our Quarterly Journal, he was best known as a diligent and successful collector of fossils. In that capacity he did good service to the science, and the valuable series of specimens, amount- ing to more than 20,000, which he gathered together, now form part of the treasures of the British Museum and the Museum of Practical Geology in Jermyn Street ; while a portion of them has found a place in the Devizes Museum, of which he was one of the founders and the honorary curator. He will be remembered among those enthusiastic and helpful cultivators of geology to whose industry, as collectors of fossils, so much of our knowledge of the faunas and floras of the English Secondary rocks is due. He joined the Society in 1854, so that he had continued to be a Fellow for more than half a century. George Frederick Harris, born in 1862, turned his attention at an early age to geology and archaeology, and enlarged his experience by travel in Europe, Northern Africa, and the United States. Some of his observations abroad formed the subject of papers published in the ' Geological Magazine.' He devoted much time and thought to the details of Tertiary geology, more especially to the mollusca of foreign Tertiary formations. In conjunction with our Fellow, Mr. Henry "W. Burrows, he published an account of the Eocene and Oligocene divisions of the Paris Basin. He prepared a volu- minous Catalogue of the Tertiary Mollusca of Australia contained in the Geological Department of the British Museum, and added an Appendix to Mr. E. B. Newton's Systematic List of British Oligo- cene and Eocene Mollusca in the British Museum. But besides these and other contributions to the strictly scientific side of geology, he showed a livery interest in the economic applications of our science, which he thought were too little regarded by geologists, especially by those in official positions. For more than twenty years he was a contributor to the ' Builder,' and published in that journal a series of useful articles on ' Building-Stones ' which were afterwards issued as a separate volume. Another practical work of his appeared with the title of ' Granites & Granite-Industries/ while a third was devoted to ' The Science of Brickmakinsr.' Having received a part of his education at the Birkbeck Institution, he continued in after-life to manifest his interest in that establish- ment, and for nearly twenty years was its Lecturer on Geology. He became a Fellow of this Society in 1885. After a prolonged lxviii PROCEEDINGS OF THE GEOLOGICAL SOCIETT. [Ma J I907, illness he died on the 16th of last July at his residence, Thornton Heath (Surrey). In that numerous and active band of observers to whom geology owes so much, who devote their leisure to the collection of the fossils of their own districts, and who place their specimens and their observations at the service of all who can put them to good use, there has for half a century been no one more widely known and respected than John Ward, of Longton (Staffordshire), whose death took place on the 30th of Xovember, 1906, in the 69th year of his age. With untiring zeal and conspicuous success he spent the scanty spare hours of a busy life in the study of the Xorth Staffordshire Coalfield, more especially with a view to the determi- nation of the distribution of its organic remains. He early saw the importance of ascertaining the exact horizons of the fossils dispersed through the strata. More than forty years ago he detected the occurrence of marine organisms in the Coal-Measures of his district. In the course of years he accumulated a fine series of the fossil-fishes of these strata, which were submitted to and described by the most accomplished palaeontologists of the day, and the chief part of which is now among the riches of the British Museum. His collection of the Carboniferous mollusca and plants has likewise supplied important fresh material for the increase of our knowledge of the fauna and flora of the Coal-Measures. Although he was so diligent a collector and knew so well the geological interest and significance of his specimens, he published only a small part of his knowledge in the form of notes, letters, and papers. But his stores of information were ever placed at the disposal of all interested in the subject. His name will be perpetuated in the designation of many fossils which he discovered. He joined our Society in the year 1874 ; and in 1899 he received a moiety of the Lyell Fund, in recognition of the value of his prolonged devotion to geological research. Thomas Leighiox was born in 1858, and, after completing his education at Stuttgart, he entered under his father the bookbinding firm of Leighton, Son, & Hodge, which had been established as far back as 1767. He became a partner in 1889, and in 1898, when his brother quitted the business, he practically took over the entire management. His knowledge of the trade was recognized by his being elected Chairman of the Bookbinding section of the London Vol. 6$.~\ ANNIVERSARY ADDRESS OF THE PRESIDENT. lxix Chamber of Commerce. But, while thus fully immersed in mer- cantile pursuits, he found time to cultivate the taste for natural history which he had shown from his boyhood. It appears to have been after the year 1886 that he gave his special attention to geology, for he then inherited the geological collection and library of his uncle, W. H. Leighton. It was chiefly among the Cretaceous and Tertiary formations that he found scope for his work in the field. He communicated to the Society a paper on ' The Lower Greensand above the Atherfield Clay of East Surrey,' which appeared in the volume of our Quarterly Journal for 1895. He also wrote papers on the same subject and district in the ' Proceed- ings ' of the Geologists' Association, likewise on the Greensand and Tertiary series of the Isle of Wight and on the Barton Beds of the Hampshire Coast. He acted as Excursion Secretary to the Geolo- gists' Association for the six years from 1890 to 1896, and was indefatigable in his attention to the duties of that office. He was elected into the Society in 1S91. His death took place suddenly on November 10th, 1906. The Geological Society having watched with interest and sym- pathy the foundation and vigorous growth of a younger institution devoted to the same scientific aims with itself, I may express our sincere regret that the Geologists' Association should have lost in Percy Emary its indefatigable Secretary, who for nine years devotedly watched over its progress. He was elected a Fellow of the Geological Society in 1897. If he has left no record of original scientific work, the yearly volumes of the Association for which he laboured so hard will remain an enduring monument of his services in the cause of geological advancement. VOL. LXIII. / 1XX PROCEEDIXGS OF THE GEOLOGICAL SOCIETY. [May I907, February 27th, 1907. Sir Archibald Geikie, D.C.L., Sc.D., See.R.S., President, in the Chair. John Gerrard, H.M. Inspector of Mines, Worsley, Man eh ester ; Thomas "Walter Joyce, Borough Engineer's Office, Dartmouth ; and Lawrence William Kershaw, 62 Yivian Road, Harborne, Birming- ham, were elected Fellows of the Society. The List of Donations to the Library was read. The following communications were read : — 1. 'On the Lower Ordovician Succession in Scandinavia.'1 By William George Fearnsides, M.A., F.G.S. 2. 'The Occurrence of Pseudomorphous Pebbles of Pyrites at the Crown-Reef Mine (Witwatersrand).' x By Cuthbert Baring Horwood, A.R.S.M., Assoc.M.Inst.C.E., F.G.S. The following specimens, maps, etc., were exhibited : — Rock-specimens and fossils from the Lower Ordovician of Scandinavia, exhibited by W. G. Fearnsides, M.A., F.G.S., in illustration of his paper. Specimens containing pseudomorphous pebbles of pyrites from the Crown-Reef Mine (Wit.watersrand), exhibited by C. B. Horwood, A.R.S.M., Assoc.M.Inst.C.E., F.G.S., in illustration of his paper. A recent specimen of Beryx splendens, bought in the London Market, probably from the coast of Portugal, a near ally of the Cretaceous fishes now known as Hoplopteryx, exhibited by E. T. Newton, F.R.S., F.G.S. Geological Survey of England &. Wales : 1-inch map, n.s. Sheet 311— Wellington (Drift) by W. A. E. Ussher (colour- printed), presented by the Director of H.M. Geological Survey. Geologic Atlas of the United States Geological Survey : Folios 136-140, 1906, presented by the Director of that Survey. Geological map, in two sheets, 1 inch = 4 miles, 1906, from the Victoria History of the Counties of England : Devon, vol. i, executed and presented by W. A. E. Ussher. Royal Hungarian Geological Survey: 75000 gecuooical maP — Krassova & Teregova, by L. Roth, F. Schafarzik, K. von Adda, & J. Bockh, 1903, presented by the Director of that Survey. Withdrawn by permission of the Council. Vol. 6t).'] proceedings of the geological societi. lxxi March 13th, 1907. Aubrey Strahan, Se.D., F.R.S., Vice-President, in the Chair. Gerald de Parcel! Cotter, B.A., Assistant-Superintendent of the Geological Survey of India, Calcutta ; Arthur Dance, Mining- Engineer, Pretoria (Transvaal) ; Felix Oswald, D.Sc, Iona, Beeston (Nottingham) ; and William Henry Pickering, Chief Inspector of Mines in India, 5 Fancy Lane, Calcutta, were elected Fellows of the Society. The List of Donations to the Library was read. The following communications were read : — 1. ' A Silurian Inlier in the Eastern Mendips.' By Prof. Sidney Hugh Reynolds, M.A., F.G.S. 2. ' On Changes of Physical Constants which take place in certain Minerals and Igneous Rocks, on the Passage from the Crystalline to the Glassy State ; with a short Note on Eutectic Mixtures.' By James Archibald Douglas, B.A., F.G.S. The following specimens, maps, etc., were exhibited : — Rock-sections, specimens, photographs, and lantern-slides, ex- hibited by Prof. S. H. Reynolds, M.A., F.G.S., in illustration of his paper. Lantern-slides, exhibited, by J. A. Douglas, B.A., F.G.S., in illustration of his paper. Nineteen sheets of the 6-inch Geological-Survey map of the Derbyshire & Leicestershire Coalfields, surveyed by C. Fox- Strangways & W. W. Watts; seventy-four sheets of the 6-inch Geological-Survey map of the South- Wales Coalfield, surveved bv T. C. Cantrill, W. Gibson, A. Strahan, & R. H. Tiddeman,"l905"; also 1-inch Geological-Survey map, n.s. Sheet 346, Newquay (Drift) by C. Reid, J. B. Scrivenor, & D. A. MacAlister ; and Sheet 352, Falmouth (Drift) by J. B. Hill, E. E. L. Dixon, & D. A. MacAlister, both sheets colour-printed, 1906, presented by the Director of H.M. Geological Survey. Geologische Karte des Grossherzogthums Hessen, ^Joo* Blatt Yiernheim (Kaferthal) von W. Schottler, 1906, presented by the Director of the Grand Ducal Survey, of Hesse. Ixxii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May I907. March 27th, 1907. Sir Archibald Gelkie, D.C.L., Sc.D., Sec.E.S., President, in the Chair. Richard George Muir Bathgate, Kendwadih, Kusunda P.O., E. I. R. (India) ; Harry Brian-Pearson, 19 Craven Road, Padding- ton, W. ; Thomas Crosbee Cautrill, B.Sc Lond., Geological Survey of England & Wales, 28 Jermyn Street, S.W. ; Satis Chandra De, M.Insfc.M.E., University of Birmingham ; and Hugh Septimus Gordon, 9 St. Germans' Place, Blackheath, S.E., were elected Fellows of the Society. The List of Donations to the Library was read. The following communications were read : — ■ 1. ' On the Southern Origin attributed to the Xorthern Zone in the Savoy and Swiss Alps.' By Prof. T. Gr. Bonney, Sc.D., LL.D., E.R.S., F.G.S. 2. ' The Coral-Rocks of Barbados.' By Prof. John Burchmore Harrison, C.M.G., M.A., F.I.C., F.G.S. The following specimens and maps were exhibited : — Specimens of corals, exhibited by Prof. J. B. Harrison, C.M.G., M.A., F.I.C., F.G.S., in illustration of his paper. Silicified wood bored by moliusca, from a well about 300 feet in the Upper Chalk at Martin, East Langdon, north-north-east of Hover (East Kent "Waterworks), exhibited bv W. Whitaker, B.A., F.R.S., F.G.S. Eleven sheets of the 6-inch Geological-Survey map of Glamor- ganshire, by R. H. Tiddemau & A. Strahan, 1905, presented by the Director of H.M. Geological Survey. Geological-Survey Index-map (1 inch = 4 miles) of Scotland, Sheets 16 & 17, 1907, presented by the Director of H.M. Geological Survey. 1-inch Geological-Survey map, Sheets 143 & 144, Limerick District (Drift) by G. W. Lamplugh, &c, 1907, presented by the Director of the Geological Survey of Ireland. '»M \ \~£T Vol. LXIII. Part 1. FEBRUARY 4th, 1907. No. 249. THE QUARTERLY JOURNAL GEOLOGICAL SOCIETY. KOITED BY THE ASSISTANT-SECRETARY [With Five Plates, illustrating Papers by Mr. A. M. Davies, Mr. R. W. Eooley, and Mr. W. R. Baldwin- Wiseman. LONDON : LONGMANS, GREEN, AND CO. PARIS:— CHARLES KLINCK8IECK, 11 RUE D SOLD ALSO AT THE APARTMENTS OF THE S^IETY Price Five Shillings. LIST OF THE OFFICERS AND COUNCIL OF THE GEOLOGICAL SOCIETY OF LONDON. Elected February 16th, 1906. Sir Archibald Geikie, Sc.D., D.C.L., LL.D., Sec.E.S. Robert Stansfield Hemes, M.A. I Aubrey Strahan, Sc.D., F.R.S. John Edward Marr, Sc.D., F.R.S. | J. J. Harris Teall, M.A., D.Sc, F.R.S. Secretaries. Prof. William Whitehead Watts, M.A., I Prof. Edmund Johnstone Garwood, M.A. M.Sc, F.R.S. dfomgn £?ecretan>. Crtasiurer. Sir John Evans, K.C.B., D.C.l', LL.D., I Horace Woollaston Monckton, Treas.L.S. F.R.S., F.L.S. e©ty)!N] MR. E. A. NEWELL ARBER ON THE UPPER [Feb. I907, Upper f f -^ar(^ rather thick, evenly-bedded Culm Measures. \ EgSesford Grits, j greJ Srits> with shales and slatr [ I beds. ( f Thickly & thinly-bedded, greenish- grey and reddish, much jointed Tivertonand Mor- sandstones, associated with ovoid- chard Types, and \ p a Wl^ng shales Ugbrooke Types. ] Bather thick, grey shales with hard, fe "ne' coarse» anci locally-conglo- meratic sandstones, irregular in 1 association. ( Interbedded, hard, thin, brown- Exeter Type. weathered grits and splintery or broken grey shales (probably a [_ local type). I have recognized both the Eggesford and the Morchard types in various localities ; but I believe them to be simply local variations, and not definite litbological facies constant over wide areas, thus clearly distinguishing a higher from a lower horizon. This conclusion is also in accordance with De la Beche's l obser- vations. He remarks that 'notwithstanding the size of the area in which they are comprised, the uni- formity of the larger part of the carbonaceous rocks, viewed generally, is one of the most remarkable circumstances connected with them, and from which we may infer considerable uniformity in the general conditions under which their constituent mud, silt, sands, and vegetable remains have been accumulated/ I have not observed any typical grits or slates among these Upper Carboniferous rocks, although others speak of such as occurring. The sandstones appear, so far as superficial observation is concerned, to be generally of a fine texture. McMahon2 came to the same conclusion from a study of the rocks near Bude. He speaks of them as being ' very fine-grained rocks,' and adds that 1 some are distinctly arenaceous, and may be called fine-grained earthy sand- stones ; but they pass gradually into argillaceous shales.' Numerous quartz-veins are often conspicuous in the sandstones, as was already noticed by Sedgwick & Murchison.3 They appear, however, to be much more frequent in the rocks to the south of Hartland Point, and in Cornwall. The shales met with in different parts of the coast-line vary con- siderably in their petrological and physical characters. One may distinguish several impersistent types, of which the black splintery and the ovoidally-splittiDg shales are among the more abundant. I have not seen any rocks that show signs of true cleavage, and McMahon 4 also apparently failed to discover any true slates. As is well known, the Upper Carboniferous rocks are highly tilted and folded, and often bent or contorted. Faulting is very common, and is clearly seen in the coast-section, where overthrust- planes are also much in evidence in several localities. Gentle 1 De la Beche (39) p. 123. 2 McMahon (90) pp. 180-109 ; see also Sedgwick & Murchison (40) p. 677. s Sedgwick & Murchison (40) p. 678. McMahon (90) p. 109 ; see also Sedgwick & Murchison (40) p. 679. Vol. 6$.~] CARBONIFEROUS ROCKS OF DEVON AND CORNWALL. 7 folds are rare, while sharp folds predominate. In some cases the anticlines are perfectly regular, and well preserved, though usually faulted through the crest, but with a small downthrow of a few feet or less. One of the best-preserved anticlines is that occurring at Tut Hole in Cockington Cliff, rather more than 2 miles south of Westward Ho ! A rough sketch of this fold, which was described as a 'hut-like contortion near Cockington Head, Bideford Bay/ was figured by De la Beche x in 1839. At present the anticline measures 50 feet in height, 70 feet across the base, but it is to some extent crumbling away above. The rocks consist of alterna- tions of sandstones and shales, occurring in an area in which shale- beds for the most part prevail. I am indebted to Mr. Rogers for carefully measuring the dimensions of the fold. Other anticlines on an even larger scale, and almost equally regular, if not quite so well-preserved, are to be found along the coast, especially to the south of Hartland Point. McMahon a has well described those occurring near Bude. In some parts of the coast-section, sigmoidal and overthrust- folds are extremely conspicuous in the cliffs. The contortions may be so numerous as to be evident in a hand-specimen. Not only can every stage in the formation of these complicated folds be traced, but the rocks concerned show abundant evidence both of crumpling and of compression and crushing. Contorted rocks are especially conspicuous at Dyer's Lookout, near Blackpool Mill, to the north of Hartland Quay, and also at Broadbench Cove, rather more than a mile to the north of Welcombe Mouth, near the border- land of Devon and Cornwall. McMahon 3 has described some of those occurring in the neighbourhood of Bude, and has given a sketch of the contortions at Efford Ditch, to the south of that town. Fig. 1 (p. 8) shows the contorted shales and sandstones exposed in the sea-cliff north of Broadbench Cove. For this photograph I am indebted to Mr. W. H. Friendship, of Bideford. It was taken, with the assistance of Mr. I. Rogers, under great difficulties. The rocks in this district may probably be regarded as typical of the Upper Carboniferous Series of Devon and Cornwall. McMahon has studied the petrology of the rocks around Bude, and has given a chemical analysis of one specimen. It may be of interest to recall that he paid special attention to those beds which had under- gone the greatest amount of crumpling, compression, and crushing, to ascertain whether any mineralogical changes had taken place. The conclusion at which he arrived was that they are practically unaltered. He regarded these deposits as derived, not from the weathering of a pre-existing tract of sedimentary rocks, but ' from the waste of a crystalline area,' the materials of which ' appear to have been deposited in tranquil water undisturbed by strong currents.'4 1 De la Beche (39) p. 123. - McMahon (90) p. 106. 3 McMahon (90) p. 106 & text-fig. on p. 107. 4 McMahon (90) pp. 112, 113. 8 ME. E. A. NEWELL AEBEE ON THE TJPPEE [Feb. 1907, Before passing on to describe the carbonaceous and calcareous rocks, I may point out that this coast-line offers a promising field for the study of certain problems of physical geology. In addition to the influence of earth-movements, so well seen in these beds, the coast-section affords excellent ground for a detailed examination of the effects of marine denudation on highly folded and contorted strata.1 There are also a number of waterfalls along the cliffs, Fig. 1. — Contorted sliales and sandstones in the sea-cliff at Broadbench Cove, north of Welcomhe Mouth (North Devon). both in Devon and in Cornwall, sometimes of quite considerable height and size, which are especially interesting in relation to the dip, the strike, and the folding of the strata, and also to the ' Mouths ' or places where access, natural or artificial, can be gained to the shore. Such would probably repay a close examination. III. The Caebonaceotjs Rocks. These occur in only one district in the whole of the Upper Carboniferous area in Devon and Cornwall. A number of incon- stant bands of ' culm ' — the old Devon name for the impure, smutty coal of the neighbourhood of Bideford — are found in the north of the county, stretching from the coast at Greenacliff through Bide- ford, for a distance of some 12| miles eastward, to Hawkridge Wood, near Chittlehampton. The disposition of these culm-bands is shown 1 See De la Beche (39) chap, xiv, p. 435. Vol. 6^.~\ CARBONIFEROUS ROCKS OF DEVON AND CORNWALL. 9 on De la Beche's map of this part of Devon. They have been repeatedly described, notably by Sedgwick & Murchison,1 De la Beche,2 Townshend Hall,3 and others ; and I have nothing material to add to what has already been said on this subject. An account of the fossil flora associated with the Bideford culm-bands has already appeared elsewhere.4 Attention may, however, be called to the fact that there is no indication that such culm-bands exist on the southern side of the basin. One would rather expect to find them near Bude in Cornwall, or to the south of that place, occupying a similar position on this side of the main syncline to those of the Bideford district in the north. A close examination of the coast-lino has not led to the discovery of any such deposits, and there is no reason to believe that carbonaceous beds, whether of sufficient thickness to be of economic importance or not, are to be found in West Devon or North Cornwall, other than in the Bideford district. In this conclusion, the provisional statement made by De la Beche,5 in 1839, to the same effect, is confirmed. It would appear, however, that some of the dark splintery shale- deposits, especially when weathered, may have been mistaken for beds of culm. No doubt this error is at the base of the local tradition that culm occurs, and has been worked, in the neighbourhood, of Hartland, at a spot near a road still known locally as Coalpit Lane. The results of a special enquiry into the matter, however, have tended to show that no culm exists, nor any trace of culm- workings, similar to those still to be found along the strike of the culm-bands in the Bideford district. Nor can an}^ culm be found in the coast-section, not far distant from this spot. Possibly these rocks may once have been worked, to some small extent, under the belief that they were of a nature similar to those near Bideford, whereas, in reality, they consist of weathered black shales. I am especially indebted to Mr. Rogers for investigating the facts of the matter, to which my attention had been repeatedly called by residents in Devon. As I have already pointed out elsewhere,6 it is in the general absence of carbonaceous deposits that the greatest contrast is to be found between the Upper Carboniferous Series of Devon and the Coal Measures of other British areas. So far as the sand- stones and shales are concerned, there is a general lithological resemblance, which is confirmed by the discovery of numerous marine beds, to be discussed at a later stage in this paper. A study of the state of preservation of the plant-remains found in the higher beds of the trough may perhaps throw some light on the question why this district is so generally barren of carbonaceous deposits. This barrenness is probably not due to any lack of 1 Sedgwick & Murchison (40). 3 De la Beche (39) pp. 124 & 513. 3 Hall (75). 4 Arber (04). 5 De la Beche (39) pp. 102 & 515. 6 Arber (04). 10 ME. E. A. NEWELL AEBEE OX THE UPPER [Feb. I907, material of vegetable origin. On the contrary, plant-impressions are abundant throughout, although extremely fragmentary, and badly preserved.1 There is little indication that their fragmentary nature and decayed aspect are in any way due to the effects of the folding and contortion which these rocks have undergone. The most intelligible explanation appears to me to be that the material, drifted from a neighbouring land-area, was deposited in a region sub- ject to the action of strong currents. In the sandstones themselves, current-markings are extremely frequent. The whole aspect of the plant-remains is explained by the supposition that the vegetable material was repeatedly tossed about and broken up by currents. Such conditions also explain the decayed appearance of the fossils, due to prolonged immersion before they became covered up in the mud or sands of the estuary. The same currents would also tend to sweep away and scatter far and wide any accumulation of material, which if deposited in quieter waters might ultimately have formed coal-seams. In the Bideford district only, the con- ditions of deposition, for some reason or other, appear to have been comparatively free from the disquieting influences of such currents, and thus favourable for a sufficient accumulation of material to form a coal-seam. The better preservation, and more complete nature of the plant-remains in this district, supports this conclusion, which, however, is opposed to that arrived at by McMahon3 | see p. 7 | from a study of the petrology of the Cornish rocks. IV. The Calcareous Rocks. As the result of a close examination of the Upper Carboniferous rocks of Devon and Cornwall, it has been found that calcareous deposits, partly of marine and partly of freshwater origin, are much more abundant than had been previously supposed. It is true that Vancouver in 1808, and Sedgwick & Murchison in 1840, men- tioned the fact that such beds are here and there associated with the sandstones and shales : but. at a later period, it appears to have been imagined that they probably belonged to some portion of the Lower Carboniferous Series, in which limestones have been long known to occur. At least, in 1885, we find Pengelly,3 one of the foremost of Devon geologists, positively asserting that such rocks are unknown in the higher Carboniferous sediments of the Hartland and Clovelly district. Both in Devon and Cornwall, however, not only are concretionary beds, composed of calcareous nodules em- bedded in shales, far from rare; but well marked, if impersistent and inconstant, bands of impure limestone are also present. 1 Sedgwick &c Murchison (40) p. 678. 2 McMahon (90; pp. 112. 113. 3 Pengelly (85) pp. 425-26. Vol. 63.] CAEBONIFEROUS ROCKS OP DEVON ANJ) CORNWALL. 11 (a) The Impure Limestone-Bands. Vancouver,1 in his * Agriculture of the County of Devon,' pub- lished in 1808, mentions the occurrence of these limestones in a number of localities, some of which, such as Chittlehampton, Bishop's Nympton, King's Nympton, and Eomansleigh, etc., are situated on Upper Carboniferous rocks. He states that the lime- stones have been worked in certain of these places. Sedgwick & Murchison 2 remark that ' among the accidental beds we may also notice calcareous shale passing into thin, impure bands of limestone, of which we saw an example near Hather- leigh.' [Also that] ' similar thin impure beds of limestone are found in several other places in the upper culm-measures.' These localities all lie considerably to the east of the district described here, and I have not visited any of them. It seems, however, clear that the occasional occurrence of thin limestone- bands in the Upper Carboniferous rocks of North Devon was known before 1808, although this fact appears to have been lost sight of in more recent times. In a short note, published in 1904,3 1 announced the discovery, by Mr. Eogers, of a well-marked limestone-band, exposed in a sharp anticlinal fold, to be seen in the coast-section a short distance (about 300 yards) east of Mouthmill and Blackchurch Rock, and between 1^ and 2 miles along the coast north-west of Clovelly. This band may be spoken of as the Mouthmill Limestone. It overlies a thick shale-bed containing a very large number of calcareous nodules of all sizes, especially in the upper layers where it adjoins the limestone. The limestone on the north side varies from 9 to 20 inches in thickness. On the south side of the anticline, it isimper- sistent, and soon disappears altogether. Sections of the limestone were kindly examined for me by Mr. J. A. Howe, F.Gr.S., who pronounced the rock to be an impure limestone. The limestone, as well as the nodules in the shale-bed below, contains numerous goniatites, in the form of casts often filled with calcite, as well as other fossils (p. 24). The origin of the limestone appears to be similar to that of the calcareous nodules ; but, the lime being more abundant in the first case, a definite band has been formed. Although the Mouthmill Limestone remains the best example of a limestone that I have seen from the Upper Carboniferous sequence of Devon, other but highly -impure bands have been subsequently discovered, and probably such rocks are not infrequent throughout the extent of these beds. In July 1904, Mr. Eogers, while re- examining the coast-section of Cornborough Cliffs between West- ward Ho ! and Greenacliff in North Devon, recognized a number of lenticular bands of impure limestone. More than twenty have since been identified. The lenticular form of these beds is very 1 Vancouver (1808) pp. 57-63. 3 Sedgwick & Murchison (40) p. 678 ; and footnote on pp. 678-79. s Rogers & Arber (04). 12 MR. E. A. NEWELL ARBER ON THE UPPER [Feb. I907, well seen in the cliffs, their entire length often not exceeding 5 feet, while some are not more than 2 feet long. They vary from 4 to 10 or 12 inches at their greatest width, and thin out to less than an inch at either end. The light-fawn colour of the weathered surface of the bands when dry, and their deeper, brown colour when wet, renders them conspicuous against the dark shales prevailing in this region. Search has been made for similar lenticular bands farther west- ward, in the direction of Clovelly, but they have not been observed so far. One was recognized in Cornwall, however, on the north side of Lower Sharpnose Point, some miles to the north of Bude. The bed in question varied from 21 to 24 inches in thickness, and the weathered surface closely resembled that of the bands occurring near Westward Ho ! A calcareous spring was also observed about 2 miles south of Bude, and north of Phillip's Strand. It issues from the face of the cliff, some 15 to 20 feet above the shore-line, and deposits masses of tufa, several inches thick. Obviously, calcareous rocks, although not observed in the coast-section, must occur not far distant from this spot. McMahon,1 however, failed to find any evidence of such rocks near Bude. The composition of these rocks varies considerably, as to the amount of lime present ; but in all the cases tested they w^ere found to effervesce briskly with an acid. Mr. Howe has very kindly made a preliminary examination of several specimens for me. An example of one of the many bands in the Cornborough Cliffs was pronounced to be an impure limestone. Mr. Howe says that, in section, it appears as a very fine-grained, brownish, opaque rock with a microscopic mottling due to incipient crystallization of a yellow-stained carbonate. Minute fragments of vegetable tissue, pyrites-specks, and quartz-grains are also present. Another, from a thick band in an anticline in the Abbotsham Cliffs, is described as a fine-grained, even-textured sandstone with a muddy calcareous cement. A specimen, typical of one of the smaller bands, is defined as a sandy, calcareous mudstone, in which the sand-grains are exceed- ingly fine but fairly abundant, and the calcareous cement subordinate and local. Parts of the rock do not effervesce with acid. Another, from Abbotsham Cliff, is a fine-grained, muddy, and calcareous sandstone, similar to the last but rather coarser, and more sandy. Fragments of plant-impressions occur in it. The last specimen, also from Abbotsham Cliff, is termed by Mr. Howe a muddy limestone. The only fossils that have been found in these limestone-bands are fairly well-preserved pith -casts of Catamites Suckoivi, Brongn., and fragments of fronds of Alethopteris lonchitica (Schl.), of which several examples have been collected. No goniatites have ever been obtained from them. The original rocks, now converted into 1 McMahon (90) p. 109. Vol. 63.] CARBOXIFEKOUS ROCKS OF DEVON AND CORNWALL. 13 impure limestones, were probably deposited in shallow water, and thus differ, as to the conditions of deposition, from the more marine type of goniatite-bearing limestone at Mouthmill, described above. (b) The Calcareous Nodules and their Fauna. In a previous note, Mr. Rogers and I1 called attention to the occurrence of calcareous nodules in the Upper Carboniferous beds of Devon, containing a marine fauna similar to that which has been found to occur elsewhere in the Coal Measures of Britain.2 Since the appearance of that paper, the distribution of these nodule-beds has proved to be even more extensive than we were aware of at that time. Nodular beds in the Upper Carboniferous rocks of Devon have been briefly noticed by Sedgwick & Murchison, De la Beche, Townshend Hall, and Ussher, but none of these observers were apparently aware of their calcareous nature. De la Beche,5 speaking of the Culm-beds of the Bideford district, states that ' nodules of argillaceous ironstone are often found in the same localities with the shale and anthracite, reminding us of the intermixture of iron-ores and vegetable matter in the bogs and morasses of the present day.' [Further, he speaks of] ' the shale with vegetable compressions and ironstone-nodules on the north side of Cockington Head.' Sedgwick & Murchison 4 also noticed that ' nodules of clay-ironstone are occasionally associated with the hard beds of sandstone ; and sometimes they occur in beds, or rows, subordinate to the shaky bands.' Townshend Hall,'5 in 1876, described nodules from Instow in North Devon, containing fish-remains and goniatites. In 1892 Mr. Ussher mentioned the occurrence of conglomeratic and con- cretionary beds 6 in his detailed description of the coast-section of the Bideford district. The nodular beds occurring in Devon, as in other Carboniferous tracts, are greatly varied. Some nodules are soft, pure sandstone- nodules, with a fair amount of iron, sometimes of a rusty-brown colour when weathered. Others are hard shale-nodules, sometimes also apparently containing a certain percentage of iron. But I have never seen any specimen from Devon or Cornwall that at all resembles the true clay-ironstone nodules, so common in the Midland and Northern coalfields of England, in which well- preserved plant-remains frequently occur. I am inclined to think that the ' argillaceous ironstone ' of De la Beche and the ' clay- ironstones ' of Sedgwick & Murchison mentioned above7 are 1 Eogers & Arber (04). 2 Stobbs & Hind (05) ; also Stobbs (06). 3 De la Beche (39) p. 125. 4 Sedgwick & Murchison (40) p. 678. 5 Hall (76). B Ussher (92) pp. 148, 149, & 153. 7 Greenough, on his Geological Map of England, published in 1819, notices. ' elay-ironstone ' near Clovelly. Probably these nodules were really calcareous, like those which I have obtained at that locality. 14 MR. E. A. NEWELL ARBER ON" THE UPPER [Feb. I907, probably identical with the concretionary structures described here as calcareous nodules, which, both in their composition and in their included fossils, differ entirely from true clay-ironstone nodules, and agree remarkably with the nodular concretions of marine origin found in North Staffordshire, Yorkshire, and Lancashire. The calcareous nodules found in Devon and Cornwall nearly always occur in thin beds of shale, which are 2 to 3 feet thick, or more rarely of greater extent. The nodules vary much in shape and size. The smaller tend to be somewhat globular, the larger are more oval or biconvex in shape. A small nodule may be only 2 inches along its greatest diameter, while a larger one may exceed a foot in length : a length of about 6 inches being an average size. The weathered surface is often somewhat iron-stained, and tends to flake off. They are of a compact texture, hard to the hammer, and break irregularly. They usually effervesce freely on the application of dilute acid. Other nodules, however, also occur which are apparently not calcareous, although closely similar to those under •discussion. The calcareous nodules commonly contain a marine fauna. Casts of goniatites are common, the cast being often filled with calcite. Impressions of lamellibranchs are not infrequent, and, like the goniatites, are irregularly distributed in the nodule. An account of this fauna will be given at a later stage in this paper (p. 23). Obscure plant-fragments are occasionally associated. Mr. Howe has kindly examined one or two typical nodules for me. An example from the north side of Lower Sharpnose Point in Cornwall, is a fine-grained, muddy sandstone, with a little mica : there being enough calcareous cement to cause mild effervescence. Another, also obtained in situ on the west side of Clovelly Harbour, is a siiicified mudstone : it might be called an impure chert. There is a certain amount of calcareous cement, but not much, and the rock scratches glass. A third nodule, containing indications of goniatites, found under Gallantry Bower, north-west of Clovelly, proves to be scarcely calcareous at all, but is probably a decomposed example of a rock like that from Clovelly Harbour. It would appear that most of the Upper Carboniferous rocks in Devon and Cornwall contain a little calcite. McMahon1 found evidence of this mineral in the beds near Bude, and states that veins occur in these rocks stopped with calcite. Probably the amount varies locally, and, where more abundant, the mineral appears to be aggregated into nodular forms or into lenticular bands. The impression left by a detailed examination of the Devon and Cornish coast-line, without however any special petrological study of the beds, is that transitions may probably be found from beds containing little or no calcite to concretionary beds of calcareous nodules, and even to thin, inconstant, and impure limestone- bands.2 1 McMahon (90) p. 109. 2 Compare the characters of the Pendleside Limestones, Hind & Howe (01) p. 395, &c. Yol. 6$.~\ CARBONIFEROUS ROCKS OF DEVON AND CORNWALL. 15 I may now give some account of the distribution of these concretionary beds in the Upper Carboniferous rocks of Devon and Cornwall ; commencing in North Devon, and passing westward and southward into Cornwall. In 1876 the late Townshend Hall1 described the occurrence of nodular beds, containing goniatites and lamellibranchs, at Instow, some 3 miles to the north of Bideford, and at the same time announced the discovery by Mr. W. Porter, of Pilton, of a specimen of Ccelacanthus elegans (Newb.) from the same beds. At a later period, another fish, Elonicliiliys Aitkeni, Traq., was found in this locality. These specimens, all of which are now in the British Museum (Natural History), remained the only fossils known from the Upper Carboniferous of North Devon, with the exception of plant-remains, until the beginning of the present enquiry in 1903. The Instow beds have been again examined on several occasions. The)' lie almost in a direct line with the mouth of the estuary of the Torridge and Taw, rather less than a mile distant, along the right bank of the former river, from Instow Station. The nodule-beds are uncovered only near low water, and at present are much obscured by sand and seaweed. The nodules, although usually washed out by the scour of the tidal river, no doubt occur in definite beds of shale, as in other districts. They are found on either side of a low and much denuded anticline. Nodules containing Gastrioceras carbonarium (von Buch), Dimorphoceras Gilbertsoni (Phill.), and Pterinopecten papyraceus (Sow.), may still be obtained in the neighbourhood of this fold, but fish-nodules are now very rare, and probably were always scarce. Mr. Rogers, however, has had the good fortune to discover a fine and almost perfect specimen of Ccelacanthus elegans (Newb.) in excellent preservation, of which there are only two other examples known from Devon. The fish- nodules are tougher and more compact in texture than the ordinary calcareous nodules, although they contain enough lime to effervesce freely with acid. The only plant-remains found at Instow are imperfect fragments occurring in some of the shell-nodules, chiefly obscure Calamite-casts. Calcareous nodules have also been found in Hubbastone Quarry and at Appledore,2 on the opposite side of the river Torridge. Mr. Ussher 3 has already noticed the concretionary beds at the last- named locality, and also along the coast-line towards Clovelly. On the other hand, I have not observed any calcareous nodules closely associated with the culm-bands of the Bideford district, although De la Beche 4 speaks of nodules of argillaceous ironstone as occurring with the so-called * anthracite ' (see p. 13). The nearest concretionary beds to the culm-bands, with which I am acquainted, are those at Cockington Head near the anticline described on p. 7, which lies nearly a mile to the southward. Two beds of nodules, 1 Hall (76). 2 The names of localities mentioned here are all shown on the 6-inch Ordnance Survey maps of Devon & Cornwall. 3 Ussher (92) pp. 148-53. De la Beche (39) p. 125. 16 ME. E. A. XEWELL ARBER OX THE EPPER [Peb. I907, without goniatites, are found on the west side of Cockington Head, which are probably those noticed by De la Beche,1 and termed ' ironstone-nodules/" On the south side of Cockington Head and Tut Hole, a bed of shale 2 to 3 feet thick occurs, with large nodules containing Gastrioceras and Dimorphoceras, as well as plant- petrifactions. Goniatite-nodules have also been observed at several places between Cockington Head and Clovelly. They occur immediately north of the stream at Babbacombe Mouth, and here and there between Babbacombe and Portledge Mouths. Two beds are also to be found immediately on the west side of Clovelly Harbour. Farther westward, nodules occur at the base of a thick bed of shales on the south-east side of Gallantry Bower. They are also again seen before reaching the Mouthmill-Limestone anticline, and are abundant in the thick shales immediately below the limestone- band (see p. 11). Still farther west towards Hartland Point, similar nodules have been observed in Beckland Cliff, on the west side of AVindburv Point. In the Hartland district they are quite abundant. Thev have been found in Coalpit Lane, and in Hescott Quarry east of Hartland village ; and on the coast, south of Hartland Point, several beds are recorded by Mr. Bogers from Blagdon Cliff, Upright Cliff, Blegberry Cliff, on the south side of Damehole Point, and in Warren Cliff near Hartland Quay. Between Hartland Quay and Marsland Mouth, the latter being the boundary between Devon and Cornwall, nodules occur at Sandhole Beach, about half-a-mile north of Xabor Point, and at Gull Bock Beach on the south side of the same Point. On the south side of Broadbench Cove, still farther towards TTelcombe and Marsland Mouths, a well-marked band of large goniatite- bearing nodules was found. The next locality to be mentioned is north of Shag Bock, near Knap Head, where large nodules were also obtained. Along the Cornish coast-section, similar beds were observed on the north side of Lower Sharpnose Point, and near Sandy Mouth, both to the north of Bude. The farthest point southward, at which these concretionary rocks have been found, is on the south side of Cambeak, near Trevigne, some 4 miles to the north of Boscastle. High Cliff probably stands somewhere near the southern boundary of the Upper Carboniferous rocks in West Cornwall. The beds developed in the bay north of High Cliff, and well seen in the large landslip by which the road passes to the beach, are typical of the Upper Carboniferous Series of Devon and Cornwall, and contain goniatite-bearing nodules. These calcareous beds are thus widely distributed, and of common occurrence, throughout the whole of the Upper Carboni- ferous sequence in both Devon and Cornwall. They commonly contain a marine fauna, especially goniatites. which will be further noticed at a later stage in this paper. 1 De la Beche (39) p. 125. Vol. 63.] CARBONIFEROUS ROCKS OF DETOX AND CORNWALL. 17 V. The Fossil Flora and the Horizon of the Beds. As already stated, the chief object of this enquiry was to discover the horizon of the highest beds of the Upper Carboniferous Series as developed in Devon and Cornwall, by an examination of the fossil plants which they contain. It has also been pointed out that, .although the rocks are everywhere greatly disturbed, and therefore the working-out of the original sequence of the deposits is practically impossible, there is reason to believe that the highest beds are those which occupy roughly the centre of the trough.1 So far as I can distinguish, these beds, as seen in the coast- section, differ neither in lithological aspect (see p. 5) nor in palseontological facies, from those, developed nearer the edges of the basin, which underlie them. It has been seen that the goniatites and other marine invertebrates occurring in calcareous nodules are •distributed practically uniformly throughout the Upper Carboniferous sequence in Devon and Cornwall. Such plant-remains as it has been possible to obtain from the beds occupying the centre of the basin have proved to be species common in the Middle Coal Measures, the horizon to which the Bideford beds also have been shown to belong.2 Unfortunately, the number and preservation of the specimens leave much to be desired. Although fragments of plant-remains are often extremely abundant, and of common occurrence, it is rare to find a specimen, or fragment, sufficiently well preserved to permit of specific identification. In fact, the task of obtaining a representative flora from these rocks proved well nigh hopeless, and such examples as have been procured are the result of much labour, and continuous search spread over many weeks. Of the thousands of ill-preserved fragments that I have seen, I have never found one which in the least recalled any of the typical Upper Coal Measure plants. All the evidence, so far as it is trustworthy, points to the conclusion that the highest beds to be found in the Carboniferous basin of Devon and Cornwall belong to the Middle Coal Measures.' (a) The Plant-Impressions. The following impressions have been obtained from localities which are believed to be situated on higher beds than those found in the Bideford district. Catamites SucJcowi, Brongn. and Calamocladus equisetiformis 1 The general extent of these beds is roughly indicated in Mr. Ussher's recent map (Ussher [01J pi. xvi), where they are shown uncoloured but with a fine hatching, and are marked C5 in the index to the Map. They form the Upper Culm Measures in Mr. Ussher's classification. * Arber (04) p. 316. 3 This horizon is termed the ' Westphalian ' by Mr. Kidston, (05) p. 319, in his revised terminology for the zones of Upper Carboniferous age, founded on palaeobotanical evidence. I regret, however, that I am unable to adopt the new terms proposed, for several reasons, among which I may mention the use of the term Westphalian, which has long been employed on the Continent in a far wider sense than that now adopted by Mr. Kidston. Q. J. G. S. No. 249. c 18 ME. E. A. KEWELL AEBEE ON THE TIPPER [Feb. I907, (SchL), both widely distributed species in the Coal Measures, occur in tbe shales on the shore on the west side of Gauter Point, near Buck's Mill Month. On the west coast, at Speke's Mill Mouth, a short distance to the south of Hartland Quay, the following plants were obtained :^- C'alamocladus cf. 0. equisetiformis (SchL). Annul aria (?) sp. Sphenophyllum sp. Alcthcpteris lonchitica (SchL). Mariopteris muricata (SchL). Lepidophyllum (?) . Stigraaria sp. Farther south, at Embury Beach, between Speke's Mill Month and Welcombe Mouth, a Splienopteris, a Sphenopliyllum, and a Galamite were collected, but the species could not be determined. At Welcombe Mouth, within a mile of the boundary betweeu Devon and Cornwall, the following plant-remains were obtained. Annularia sp. Alethopteris lonchitica (SchL). Sphenoptcris sp. Stigraaria ficoides (Sternb.). Still farther south, in Cornwall, a Calamite was found near Litter Mouth ; and, at Warren Gutter Beach, specimens of Catamites Suckowi, Brongn., and Stigmaria ficoides (Sternb.) were obtained. A more interesting discovery, however, was made on the north side of Higher Sharpnose Point, where a specimen which may be compared with Dactyloilieca plumosa (Artis) was collected. These fossils do not, in themselves, afford sufficient evidence to determine the horizon of the beds. They are, however, from rocks which are known to overlie sediments belonging to the Middle Coal Measures ; and, as already stated, there is a total absence of any plants which are especially characteristic of the Upper Coal Measures. Further, so far as they go, they are indicative of a Middle rather than of an Upper Coal Measure horizon. Nearly all of them have also been found in the richer plant-bearing beds of the Bideford district. Several new localities and new species have also been discovered in the Bideford district, chiefly through the energy of Mr. Bogers. These supplement the already published account of the flora of that district. Neuropteris tenuifolia (SchL), in addition to many other species already recorded from Devon, has been found in the shales closely associated with the culm-band at Greena cliff on the coast, about 2 miles from Bideford. A Splienopteris (which may be compared with Sph. microcarpa, Lesq.) and Neuropteris acuminata (Schl.) were also collected from shales about 100 yards north of the culm-band above mentioned. At Summer Hiscott, a locality already mentioned in my previous paper, Mr. Bogers has obtained Corynepteris Stembergi (Ett.), a Neuropteris like N. stradonitzensis (Andrae), and cones referable to the genus Oalamostachys. At Pitt Quarry, Abbotsham, a Halonial branch of a Lepidophloios has been collected. SpJienopteris Hceninghausi, Brongn., has also been Vol. 6$.] CARBONIFEROUS ROCKS OF DEVON AND CORNWALL. 19> obtained at Pill Head Copse, near Bideford. These new record* all confirm the opinion already published as to the Middle Coal Measure horizon of the beds of the Bideford district. The following species have also been collected from near Bude, in Cornwall, which probably occupies a similar position on the south side of the basin to that of Bideford on the north : — Catamites Supkowi, Brongn. Catamites ramosus (Artis). Sphenopteris obtusiloba Brougn, Stigmaria ficoides (Sternb.). The following is a complete list of the fossil plants recorded from the Upper Carboniferous rocks of Devon and Cornwall in the present and previous T papers : — Equisetales. Catamites (Catamilina) wndulatus, Sternb. Catamites (Eucalamites) ramosus (Artis). . Catamites (Sty local amitcs) Suckowi, Brongn. Catamites (Calamitina) varians, Sternb. Catamites (external surface). Annularia radiata, Brongn. Annularia galioidcs (L. & H.). Calamocladus equisetiformis (Schl.). Calamocladus charceformis (Sternb.).2 Calamostachys longifolia, Weiss. Calarmostachys sp. Pinnularia sp. Sphenophyllales. Sphenophyllum cuncifolium (Sternb.). Filicales & Pteridospermese. Sphenopteris obtusiloba, Brongn. Sphenopteris Hceninghausi, Brongn. Sphenopteris cf. Sph. microcarpa, Lesq. Renaultia Footneri (Marratt). Renaultia schatzlarensis (Stur.) ? 3 Umatopteris tenella (Brongn.). Mariopteris muricata (SchL). Megalopteris (?) sp. Neuropteris obliqua (Brongn.). Ncuropteris Schlehani, Stur. \ Iseuropteris tenuifolia (Schl.). Xeuropteris acn/minata (Schl.). Iseuropteris cf. JV. stradonitzensis (Andrae). Alethopteris Serli (Brongn.). Alethopteris lonchitica (Schl.). Cf. Dactylotheca plumosa (Artis). Corynepteris Sternbergi (Ett.). Lycopodiales. Lepidodendron acideatum, Sternb. Lepidodendron obovatum, Sternb. Lepidodendron fusiforme, Corda. Lepidophloios acerosus (L. & H.). Lepidophloios (Halonia) sp. Lepidophyllum (?) sp. Sigillaria scut el lata, Brongn. Sigillaria tessellata, Brongn. Stigmaria ficoides (Sternb.). Cordaitales. Cordaites (Artisia) sp. Incertae Sedis. Bark-like impression. In my previous paper,4 I stated that the occurrence of gonia- tites and lamellibranchs at Instow, in North Devon, might be regarded as evidence that the Instow beds belonged to the Lower Coal Measures. At that time it was not known that this marine fauna, abundant in the Lower Coal Measures of the Midlands, had 1 Arber (04) pp. 815-16 ; see also Hall, (75) p. 375, for a previous list, emended in my paper published in 1904 : Arber (04) p. 297. 2 In my previous paper, (04) p. 303, a slip occurs in the remarks on this species. For Calamocladus charcsformis read Annularia galioides, which is identical with Sauveur's Ammlaria microphylla. 3 I regret that the synonymy quoted for this species in my previous paper, (04) p. 306, is entirely misleading. 4 Arber (04) p. 318. c2 120 ME. E. A. NEWELL ARBER ON THE UPPER [Feb. I907, so wide a distribution throughout the whole of the Upper Carbo- niferous sequence in Devon. This new fact has modified the view then expressed. The wide occurrence of this fauna, on prac- tically the same level as the Middle Coal Measure plant-remains, shows that its presence, in itself, cannot be regarded as indicative of a Lower Coal Measure horizon. Thus, in the absence of any nora from the Instow beds, their precise horizon must remain doubtful, and at present there is no real palaeontological •evidence to show that the Lower Coal Measures are represented in either Devon or Cornwall. Before passing on to discuss the plant-petrifactions, I may briefly notice one or two collections of plants from the Upper Carboni- ferous rocks of Devon, which were not referred to in my previous paper.1 One of the earliest collectors of fossils in Devon was the late Lieut.-Col. William Harding, of Upcott, Pilton, who is mentioned Doth by Sedgwick & Murchison2 and by De la Beche.3 His collection is now in the Athenaeum Museum, Plymouth. Most of the specimens are, unfortunately, without record of the localities whence1 they were derived. A few are labelled ' N. Devon,' including Catamites from Moor Park, and Mariopteris muricata {Schl.), also from near Bideford. These, and possibly a few others, were no doubt obtained from the Upper Carboniferous rocks of Devon ; but many examples, without labels, are typical Upper Coal Measure species, most of which, in all probability, came from the Somerset Coalfield. The Somerset rocks are very charac- teristic, and in many cases unmistakable. Certainly no such shales (quite apart from the contained organisms) are to be found in Devon. I have made some efforts to obtain fuller information as to this collection, but it was formed so long ago that, at this date, it appears to be impossible to trace the localities whence the specimens were derived. Since my previous paper on the Bideford plant-remains was completed, the collection of the late William Vicar)7 has been bequeathed to the Geological Department of the British Museum (Natural History).4 It contains a few poorly preserved plants, especially Calamites, Alethopteris lonchitica (Schl.), Lepidodendron, and Stigmaria Jtcoides (Sternb.), from the Upper Carboniferous of Devon and Cornwall, but the localities from which the specimens were obtained are uncertain. I may add that the specimens from Mr. Rogers's collection, figured and described in my paper published in 1904, are now also in the Geological Department of the British Museum (Natural History). 1 Arber (04) p. 300. 2 Sedgwick & Murchison (40) pp. (>48, 682, &c. 3 De la Beche (39) pp. 50, 117, &c. 4 Kegistered Nos. V 9765- V 9783. Vol. 63.^ CARBONIFEROUS ROCKS OF DEVON AND CORNWALL. 21 (b) The Plant-Petrifactions, At an early stage in the exploration of the western shore-line of Devon, some rolled pebbles, in which small black objects were embedded, were found washed up on the beach. The rock consists of a fine-grained, grey sandstone, in which these bodies are arranged without order. Pig. 2 (below) is reproduced from a photograph of a typical specimen. These pebbles proved to be far from rare, and were obviously de- rived from the Upper Carboniferous rocks. The nature of the small, black, lenti- cular structures re- mained somewhat puzzling, until it was noticed that certain of them showed traces of structure. Microscope - sections were then prepared, and it was ascer- tained that they were in reality badly-pre- served plant - petri- factions. This dis- covery was briefly announced in 1904/ and was regarded as of some interest, since petrifactions of Upper Carboni- ferous age, showing the anatomical struc- ture of the plants of that period, are prac- tically confined in England to a single horizon, the Lower Coal Measures of Yorkshire and Lanca- shire. Consequently, a special effort was made to locate the beds from which these pebbles were derived, in the hope that better-preserved specimens might be obtained. It has been found that these impersistent conglomerates are by no means rare, for they occur, here and there, throughout the whole of the Upper Carboniferous Series in Devon and Cornwall. The petrifactions are more abundant in the sandstones, but they are S g ,5 P «i r — > JS © *■& .6}) Arber (05s). 22 MR. E. A. NEWELL ARBER ON THE UPPER [Feb. I9O7, also fairly frequent in certain shale-beds, and even occur in some calcareous nodules associated with goniatites. In the Bideford district, they have been found in Hubbastone Quarry, on the opposite side of the Torridge to Instow, and a few in the shales on the coast south of Westward Ho ! In Cockington Head, they occur in the shales containing calcareous nodules near Tut Hole, already referred to (p. 7), as well as in the associated shale-beds. Farther south, they have been observed in sandstones, both on the eastern and on the western sides of Gauter Point, and also a few yards on the west side of Buck's Mill Mouth. Beyond Clovelly, they occur in the calcareous nodules associated Fig. 3. — Section of badly preserved plant-petrifactions in sandstone from the east side of Gauter Point (North Devon). with the limestone-band in the anticline at Mouthmill, and also at a short distance to the west of Mouthmill. Between Hartland Point and Hartland Quay, several beds, chiefly of shale, have yielded petrifactions, such beds being especially abundant in Warren Cliff. Still farther south, they occur at Sandhole Beach, on the north side of Nabor Point. The petrifactions usually form a layer in the sandstones and shales only a few inches thick (see fig. 2, p. 21), but sometimes, especially in the shales, the bed containing them may be 2 to 3 feet thick. In the sandstone they are usually crowded, the longer axes of the petrifactions being sometimes more or less parallel, while in other cases there seems to be no ordered arrangement. They are cylindrical bodies, as a rule bluntly pointed at both ends. The size varies considerably : the average length is about 15 millimetres, Vol. 6$.^ CARBONIFEROUS ROCKS OF DEVON AND CORNWALL. 23 and the diameter 5 to 6 mm. In the Hartland district, however, they have been found as long as 25 mm., and with a diameter of 14 mm. A number of microscope-sections have been made, of one of which a photograph is reproduced in fig. 3 (p. 22). Unfortunately, all have proved to be badly preserved, and consequently this discovery has no botanical value. Little can be made out as to the structure, beyond the fact that these bodies are of vegetable origin. In some cases a few cells are preserved ; in others, there is an indication of a central cylinder. These petrifactions are, however, interesting geologically from the fact that they are rolled and water-worn, as their shape clearly shows. They are thus obviously derived fossils, of different origin, and possibly of earlier age, than the sandstones and shales in which they occur. Their history appears to have been briefly as follows, fragments of plants, deposited during the formation of some pre-existing beds, became partly silicified, and later these beds were denuded, and their petrifactions redeposited in the sands and muds in which they are now found. There need be, however, no great discrepancy between the ages of the two constituents of these conglomerates. VI. The Marine and Freshwater Faunas. Evidence has been found of the existence of two distinct types of fauna in the Devon rocks : the one consisting of freshwater lamellibranchs, the other of marine fishes, cephalopoda, and lamellibranchs. In this respect also, the Upper Carboniferous deposits of Devon and Cornwall agree with the Coal-Measures of Yorkshire,1 Lancashire,2 Durham,3 and North Staffordshire.4 Further, neither in Devon nor in Cornwall has any sign been seen of an intermingling of these two faunas. Thus these beds confirm the important conclusion on which special emphasis has recently been laid by Mr. Stobbs and Dr. "Wheelton Hind,5 that in North Staffordshire, and elsewhere, there is a clear and distinct separation of the marine mollusca from the freshwater forms. Although a special study of these faunas formed no part of my programme of research in Devon and Cornwall, I may mention briefly such discoveries as have been made incidentally to the main object of the enquiry. I may add that the great majority of the examples of both the marine and estuarine types obtained were collected by Mr. Iukermann Rogers, to whose skill as a collector I have already referred. The marine fauna is much the more abundant in Devon and Cornwall. The fish-remains have been already noticed (p. 15). 1 Phillips & Daubeny (45) pp. 589-90. 2 Spencer (98) p. 305. 3 Kirkby (60) p. 414. 4 Walcot Gibson (05) p. 295, &c. 5 Stobbs & Hind (05) p. 515 ; also Stobbs (06). -4 MR. E. A. NEWELL ARBER OX THE UPPER [Feb. ICJOJ, Goniatites are, as a rule, extremely common in the calcareous nodules, and they also occur in the Mouthmill Limestone. By far the most abundant species is Gastrioceras carbonarium (von Buch), which is found apparently throughout the Upper Carboniferous sequence in Devon and Cornwall, while Dimorplwceras Gilbertsoni (Phill.) is also frequent. Gastrioceras Listeri (Martin) is rarer. The lamellibranch Pterinopecten papyraceus (Sow.) is common, and ofteu associated with the more abundant species of goniatites. A similar association is found in the Midland Coalfields.1 There are indications that other genera occur, though perhaps less frequently. Ortlioceras sp. has been obtained at Mouthmill, and from Hescott Quarry near Hartland. A typical fauna is found in the Mouthmill Limestone and the associated shales with calcareous nodules, which is as follows : — Gastrioceras carbonarium (von Diniorphoecras G'tfherttoni (Phill.). Buch;. Orthoceras sp. Gastrioceras Listeri (Martin). Pteri/wpecten papyraceus (Sow.). The same species were described by Hall 2 from Instow, in JSorth Devon, in 1876. Badly-preserved shells, possibly allied to Posidoniella. were found in a rolled nodule on the beach north of Bude. In some sandy, nou- calcareous nodules at Hescott Quarry, a Myalina, possibly 31. compressa, Hind, was obtained, and other genera are probably represented. I am indebted to Dr. "Wheelton Hind, F.G.S., for several of these determinations, and to Mr. G. C. Crick, E.G.S., of the British Museum (Xatural History), for assistance in naming the cephalopoda. The freshwater mollusca appear to be much more restricted in Devon than the marine forms. The impure, lenticular limestone- bands of the Bideford district have not yielded any shells of either type so far. But, in the shales associated with the culm-bands, specimens of Carbonicola acuta (Sow.), and possibly also C. aquUina? (Sow.), have been found at Bideford, as I have already recorded.3 Mr. Rogers has since discovered other shale-beds containing this genus on the coast at Greena cliff, and at Summer Hiscott in the parish of Tawstock ; in both cases in close proximity to the culm- bands. VII. Gexeral Coxcixsioxs. The fact that by far the larger portion of the Carboniferous rocks of Devon and Cornwall is of Upper, and not of Lower Carboniferous age, as has been commonly supposed, was emphasized by the study of the fossil flora of the beds of the Bideford district in my paper published in 1904. The present enquiry has served to confirm this conclusion, by bringing into consideration evidence of a wider nature. The discovery of Upper Carboniferous faunas, 1 See Stobbs & Hind (05). 3 Hall (76). ' Arber (04) p. 319. Vol. 6$.'] CARBONIFEROUS ROCKS OF DEVON AND CORNWALL. 25 both freshwater and marine, the latter having a wide range throughout the higher beds, is especially significant in this respect. Thus these Carboniferous rocks, described by Sedgwick & Murchison as the Culm Measures, are not, for the most part, of the same age as the Culm of the Continent. Only the lower series, or Lower Culm Measures, is equivalent to the Culm of Germany and Austria ; and this, in both Devon and Cornwall, is of insignificant extent when compared with the upper division. For this reason, it would seem advisable to avoid the use of the term Culm Measures in the future when speaking of the British rocks. It is also found that the differences in lithological and palseonto- logical facies, which have been supposed to exist between the Upper Carboniferous sequence in Devon and Cornwall and their equivalents in other British coalfields, have been greatly ex- aggerated in the past. The ordinary nomenclature is as applicable to the Devon Basin as to any of our coalfields, and the Upper Carboniferous sequence there is best described as barren Coal Measures. Not only are the sandstones and shales of Devon similar to those occurring in other basins, but calcareous rocks, both of marine and of freshwater origin, are also associated. Two faunas — the one marine, consisting of fish-remains, cephalopoda, and lamellibranchs, and the other of freshwater lamellibranchs — have been found at different horizons, and both these faunas are common to other coalfields. Plant-remains are also distributed abundantly throughout the series, although in Devon and Cornwall they are nearly always fragmentary, and very badly preserved. In these respects, the Upper Carboniferous portion of the succession in the South-West of England agrees with the Coal Measures of the Midlands and the North. The chief differences appear to be two in number. Except to a very limited extent in North Devon, there is a remarkable absence of carbonaceous deposits throughout the basin. This fact may probably be corre- lated with the second point of contrast, namely, that the conditions under which these sediments were accumulated was no doubt some- what exceptional. So far as the state of the plant-remains will permit us to arrive at any conclusion on this point, these rocks appear to have been laid down in an area subject to the action of strong currents, thus preventing a sufficient accumulation of vegetable material in definite beds, which might eventually have formed coal-seams. An examination of the coast-section of Devon and Cornwall has led to the conclusion that the Upper Carboniferous sequence forms one division lithologically, as it does palseontologically. Local lithological types may be recognized here and there, but these are not constant over any considerable area and tend to merge one into the other. Thus the original twofold subdivision of the whole Carboniferous Series, instituted by Sedgwick & Murchison, is main- tained here, with the exception that the terms Upper Carboni- ferous and Lower Carboniferous Series are substituted 26 ME. E. A. NEWELL ARBER ON -THE UPPER [Feb. I907, for Upper and Lower Culm Measures. That the Upper Carboniferous Series is one division palaeontologically is shown by both the fossil flora and the fossil fauna. The assemblage of plant- remains now known from these rocks is characteristic of the Middle Coal Measures elsewhere in this country. There is no indication that higher horizons, such as the Upper Transition Series, or the Upper Coal Measures, are represented in the basin. On the other hand, the occurrence of Lower Coal Measures has not yet been demonstrated. The evidence of the fauna of the calcareous nodules, which are widely distributed throughout the basin, again supports this con- clusion. This marine fauna is practically identical from all the horizons at which it occurs in Devon and Cornwall. The badly preserved plant-petrifactions have an equally wide distribution. Briefly, the main conclusion arrived at here is that the whole of the Upper Carboniferous rocks of the great barren Coalfield of England, occupying the greater part of Devon and a considerable portion of Cornwall and Somerset, are, on the present evidence, equivalent to the Middle Coal Measures of other districts. VIII. Bibliography. Arber, E. A. N. (04). ' The Fossil Flora of the Culm Measures of North- West Devon, & the Palaeobotanical Evidence with Regard to the Age of the Beds ' Phil. Trans. Roy. Soc. vol. cxcvii, b, p. 291. 1904 [1905] . Abstract in Proc. Roy. Soc. vol. lxxiv, p. 95. 1904 [1905]. Abber, E. A. N. (051). ' On the Fossil Plants of the Upper Culm Measures of Devon ' Rep. Brit. Assoc. 1904 (Cambridge) p. 549. 1905. Arber, E.A.N. (052). 'On derived Plant-Petrifactions from Devonshire' Rep. Brit. Assoc. 1904 (Cambridge) p. 549. 1905. Arber, E. A. N. Vide Rogers & Arber (05). Ausien, R. A. C. (42). ' On the Geology of the South-East of Devonshire ' Trans. Geol. Soc. ser. 2, vol. vi, pt. 2, p. 433. 1842. Conybeare, J. J. (14). ' Memoranda relative to Clovelly, North Devon ' Trans. Geol. Soc. ser. 1, vol. ii, p. 495. 1814. De la Beche, H. T. (39). ' Report on the Geology of Cornwall, Devon, & West Somerset.' 8vo. London, 1839. Gibson, W. (05). ' The Geology of the North Staffordshire Coalfields ' Mem. Geol. Surv. 1905. Hall, T. M. (75). ' Notes on the Anthracite Beds of North Devon ' Rep. & Trans. Devonshire Assoc, vol. vii, p. 367. 1875. Hall, T. M. (76). ' Fossil Fish in North Devon ' Geol. Mag. dec. 2, vol. iii, p. 410. 1876. Hind, W. (04). ' On the Homotaxial Equivalents of the Lower Culm of North Devonshire ' Geol. Mag. dec. 5, vol. i, pp. 392, 584. 1904. Hind, W., & Howe, J. A. (01) ' The Geological Succession & Palaeontology of the Beds between the Millstone Grit & the Limestone-Massif at Pendle Hill, &c.' Quart. Journ. Geol. Soc. vol. lvii, p. 347. 1901. Hinde, G. J., & Fox, H. (95). ' On a Well-marked Horizon of Radiolarian Rocks in the Lower Culm Measures of Devon, Cornwall, & West Somerset ' Quart. Journ. Geol. Soc. vol. Ii, p. 609. 1895. Hull, E. (62). ' Marine Fossils at Dukinfield ' Trans. Manchester Geol. Soc. vol. iii, p. 348. 1862. Hull, E., & Salter, J. W. (64). 'The Geology of the Country around Oldham, including Manchester & its Suburbs ' Mem. Geol. Surv. 1864. HuiCffiNGS, W. M. (90)'. 'The Culm Measures at Bude (North Cornwall) ' Geol. ■ Mag. dec. 3, vol. vii p. 188. 1890: Vol. 6$.^ CARBONIFEROUS ROCKS OF DEVON AND CORNWALL. 27 KiDSTOx, R. (05). 'On the Divisions & Con-elation of the Upper Portion of the Coal Measures, with special reference to their Development in the Midland Counties of England ' Quart. Journ. Geol. Soc. vol. Ixi, p. 308. 1905. Kirkby, J. W. (60). ' On the Occurrence of LinguJa Credneri, Geinitz, in the Coal Measures of Durham, &c.' Quart. Journ. Geol. Soc. vol. xvi, p. 412. 1860. McMahok, C. A. (90). 'Notes on the Culm Measures at Bude (North Cornwall) ' Geol. Mag. dec. 3, vol. vii, pp. 106, 222. 1890. Pengellt, W. (85). ' Notes on Notices of the Geology & Palaeontolog3r of Devon- shire ' pt. xii, Rep. & Trans. Devonshire Assoc, vol. xvii, p. 425. 1885. Phillips, J., & Daubent, C. G. B. (45). 'Geologj-.' [Article in 'Encyclopaedia Metropolitana/] Vol. vi, p. 581. 1845. Rogers, I., & Arber, E. A. N. (04). 'Note on a new Fossiliferous Limestone in the Upper Culm Measures of West Devon ' Geol. Mag. dec. 5, vol. i, p. 305. 1904. Sedgwick, A., & Murchison, R. I. (37). 'On the Physical Structure of Devon- shire, & on the Subdivisions & Geological Relations of its old Stratified Deposits, &c.' Proc. Geol. Soc. vol. ii (No. 51) p. 556. 1837. Sedgwick, A., & Murchison, R. I. (40). ' On the Physical Structure of Devon- shire, & on the Subdivisions & Geological Relations of its older Stratified Deposits, &c.' Trans. Geol. Soc. ser. 2, vol. v, pt. 3, p. 633. 1840. Spexcer, J. (98). 'The Halifax Coal Strata' Proc. Yorks. Geol. & Polytechn. Soc. n. s. vol. xiii. (1895-99) p. 302. [1897] 1898. Stobbs, J. T. (06). 'The Value of Fossil Mollusca in Coal-Measure Stratigraphy ' Trans. Inst. Min. Engin. vol. xxx, pt. 4, p. 443. 1906. Stobbs, J. T., & Hi>td, W. (05). ' The Marine Beds in the Coal Measures of North Staffordshire: with Notes on their Palaeontologj- ' Quart. Journ. Geol. Soc. vol. Ixi, p. 495. 1905. Ussher, W. A. E. (92). 'The British Culm Measures' Proc. Somerset. Arch. & Nat. Hist. Soc. vol. xxxviii, p. 111. 1892. U sshee, W. A. E. (01). ' The Culm-Measure Tvpes of Great Britain ' Trans. Inst. Min. Engin. vol. xx, p. 360. [1900] 1901. Vancouver, C. (08). ' General View of the Agriculture of the County of Devon, &c.' 1808. Discussion. The President remarked that the Society could not but be pleased to find modern methods of detailed palaeontological and strati- graphical work successfully applied to a district which for so long a time had remained somewhat vaguely understood. The diligent search for fossils by the Author and his local friends had happily thrown new light on the Culm-Measures of Devon and Cornwall, which seemed now at last to be capable of being satisfactorily correlated with the other developments of the Carboniferous system in this country. Mr. Ussher congratulated the Author on his successful treatment of the rocks of Central Devon and North Cornwall. The results obtained fully justified the opinion unhesitatingly expressed by ♦Sedgwick & Murchison in the year 1837, that the Culm plants of Devon, as then known, proved the correspondence of the rocks with the true Coal-Measures. They referred to Prof. Phillips's view as to the equivalence of the greater part of the Culm trough to the Middle and Upper Divisions of our true Carboniferous Series. Townshend Hall, who was a pupil of Phillips, always spoke of the Culm shales and grits as ' Millstone Grit.' In definitely assigning a Middle Coal-Measure facies to the flora of the Culm grits and shales, the Author had settled this question as to the equi- valence of the rocks above the Lower Culm-Measures. The speaker was glad that the vexed question as to the equivalence of the Lower 2S UPPER CARBONIFEROUS OF DEVON AND CORNWALL. [Feb. 1907, Culm-Measures was not within the scope of the paper. The map used by the Author was (so far as regards the Central Culm area) based on the exploration of the Taw and Torridge Valleys and of the districts adjoining the New Red rocks, officially undertaken during the year .1878, with permission of the late Sir Andrew Ramsay, for the purpose of inserting alluvial lines and searching for outliers of the New Red rocks. The coast from Westward Ho I to Clovelly was then traversed, but too rapidly to detect the calcareous bands and fossiliferous nodules which the Author and Mr. Inkermann Rogers had observed in association with the shales and grits above the Lower Culm. The Instow nodules were supposed to indicate the presence of an anticline of Lower Culm, whereas they were now shown to be altogether above that horizon. The western coast and the area south of Hartland Point had never been explored by the speaker. In that area he gathered that, while the Author agreed with him in regarding the beds shown on the map as Eggesford Grits, as the upper beds of the Culm syncline, no differentiation in lithological character could be made between the Morchard (Middle Culm) and Eggesford (Upper Culm) types. These types were established for stratigraphical purposes, and were lithologically distinct in the Taw and Torridge Yalleys. The Author's researches, however, seemed to the speaker to prove that towards the western coast the Central beds troughed or frilled out in an interminable series of minor curves, and that thus the lithological distinction between the types was lost by interbedding. This constant repetition of the Culm rocks by small folds was well described by Sedgwick & Murchison. The map which had been thrown on the screen was in illustration of a paper of the speaker's on the Culm-types of Great Britain (published by the Institution of Mining Engineers in 1901), after he had ascer- tained by the actual survey of limited areas in North & South Devon and Cornwall the true succession of the Lower Culm, and placed the Posidono my a-Limestcmes above the Coddon-Hill Beds. This Dr. Wheelton Hind had rightly done near Barnstaple. He was glad to hear that the unfossiliferous limestone and fossiliferous bands and nodules found by Mr. Inkermann Rogers on the coast near Clovelly and toward Rocks Nose, Westward Ho !, were definitely placed above the Lower Culm by the Author ; and in this connexion he wished to call attention to a paper by Mr. Harold Parkinson, published by the German Geological Society in 1903, in which he described certain beds with fossils in the Nassau area above the Posidonomy a-Jjimcstones. He considered himself fortunate in having the details of a region, which he had had neither time nor opportunity to work out, rilled in by one so eminently qualified to undertake the task as the Author, with whom he cordially joined in eulogizing Mr. Inkermann Rogers's work in supplying the series of careful observations which had contributed in producing the satisfactory results embodied in the paper that they had just heard. Vol. 63.] XIMERIDGE CLAY AND CORALLIAN ROCKS OF BRILL. 29 2. The Kimeridge Clay and Corallian Bocks of the Neighbour- hood of Brill (Buckinghamshire). By Arthur Morley Da vies, A.R.C.S., B.Sc, F.G.S. (Read November 21st, 1906.) [Plate I.] Contents. Page I. Introduction 29 II. The Eid's-Hill Section 30 III. The Arngrove Stone {Bhaxella- Chert) 37 IV. Palaeontological Notes 43 I. Introduction. A few miles east of Oxford the Corallian limestones and sands disappear abruptly, and for a long distance to the east and north- east the whole of the Upper Jurassic Series between the Cornbrash and the Portland Beds consists of clay, with some local rock-beds intercalated here and there. With this disappearance of stone comes a great falling-off in the number of exposures ; therefore it is not surprising that, while the Portland and Purbeck Beds of Brill and Aylesbury have attracted much attention, the strata below them have been neglected by geologists. In the Geological- Survey memoir on the Middle and Upper Oolitic rocks of England (1895), Mr. H. B. Woodward ends a brief account of the district between Wheatley and Quainton with the sentence ' Further re- search in the district is desirable ' (p. 135). It is as a contribution to this further research that this paper is offered. The eleven years that have passed since that memoir was pub- lished have brought some changes to the district. At that time perhaps the most difficult of access of any so near to London, it is now traversed by two main lines of railway, while a third is on the point of being constructed. Large brickfields have been opened up for the supply of London and the residential districts of Buckingham- shire. On the other hand, the closing of small stone- and brick-pits continues, to the sorrow of the geologist. I began the study of the strata below the Portlandian in this district in 1899, and have visited it nearly every year since. Though most of my work has had to be carried on alone, I have to acknowledge my hearty thanks to my friends Messrs. J. H. Pledge, J. Guest, and E. W. Pocock, for help in the field-work and the pleasure of their companionship. To Mr. Pledge I am further indebted for the photomicrographs which illustrate this paper. To Mr. J. J. UfF, the manager of the Brill Brick & Tile Company, my thanks are due, not only for the full permission kindly given to work in the Company's brickfield, but also for much information readily imparted. I am particularly indebted to Mr. G.,C. Crick for the trouble that he has taken in helping me to identify the cephalopoda which I had collected ; while for assistance in identifying other fossils I have to thank Prof. H. G. Seeley, Mr. E. T. Newton, Mr. H. A. Allen, and Dr. F. L. Kitchin. I also owe some valuable sugges- tions to Dr. C. G. Cullis. II. The Bid's-Hill Section. Kids Hill is the name given on the Ordnance-map to a small hill set upon the north- eastern spur of Brill Hill, its summit marked by a little plantation of firs. Two little brooks, each arising from one of the numerous springs at the base of the Portland Sands on Brill Hill, flow north and south of Bid's Hill, on their way to the Bay and the Thame respectively; and so this hill forms part of one of the secondary lines of watershed within the Thames Basin. Along the valley of the northern stream for some little distance the road from Wotton to Brill and the so- called ' Oxford & Aylesbury Tramway' run side by side, and here, at the northern foot of Bid's Hill, are the brickfields of the Brill Brick & Tile Company. The general geological structure of the hill is shown in fig. 1. In the preparation of this section, the ground was first measured up by means of a reflecting level, along a line as near the western edge of the brick- field as possible, distances being measured by paoing. The measurements having been checked by reference to points actually marked either 1 2507 Vol. 63.] KIMERLDGE CLAY AND CORALLIAN ROCKS OF BRILL. 31 Ordnance map, contour-lines at intervals of 10 feet were sketched-in upon the latter map, and from these the profile of the section was obtained. The measurements in the brickfield were taken, partly by means of the reflecting level, and partly by tape-measurement. No attempt was made to measure horizontal distances in this case, and consequently the representation of the details of the brickfield is diagrammatic. At the top of the hill the Geological Survey has mapped Portland Sands. There are fir-trees growing here, and many rabbit-holes from which a sandy soil is thrown out, but it is by no means a pure sand ; there are no ' lydite ' or other pebbles, and under the microscope exceedingly few grains of glauconite can be detected. At the old brickfield, less than a mile to the west, which formerly exposed the junction of the Hartwell Clay with overlying strata, there is recorded below the lydite-bed 3 feet of brown and greenish mealy sand, followed by sandy Hartwell Clay.1 These beds are very probably represented at the top of Bid's Hill, but not the lydite-bed itself, the pebbles from which could not fail to be seen in the soil if it were present. 1 found no trace of Hartwell or other On the southern slope of the hill, about 90 yards from the top and 27 feet below it, I found in April 1906 that a shallow well had been dug. The material thrown out was a grey shale, with many fragments of jet or black lignite (some nearly 2 inches across). It yielded the following fossils : — Aptychus latus, Park. Ostrea sp. Exogym virgula, Defr. Cristcllaria, three or more species. These beds are evidently part of the Upper Kimeridge Clay, and differ altogether in character from those in the brickfield described below, being thorough shales instead of clays. In the brickfield at the northern foot of the hill there are, or have been, exposed about 50 feet of clayey strata. The occurrence in these clays of two bands of limestone makes clear the gentle synclinal structure of which the clays themselves give more obscure indications. Into this syncline the cutting has been made symmetrically. The highest point of this section is about 50 feet below the level of the exposure just described. The clays may be divided thus : — Feet. 8. Grey, creamy- weathering clays (zone of Exogym virgula)... 4 7. Grey, creamy-weathering clays with crushed shells, be- coming darker and slightly selenitic downwards and calcareous at the base about 17^- 6. Band of creamy limestone 1 5. Creamy calcareous clay 2 4. Band of creamy limestone 1 3. Dark grey, brown-weathering clay, with occasional phos- phatic nodules 8 2. Black shaly clay, weathering lilac-grey with yellow stains, highly selenitic 14 1. Band of grey limestone at the base, 6 feet below the floor of the pit. ,. . ,.• 1 H. B. Woodward, 'Middle & Upper Oolitic Eocks of England' Mem. Geol. Surv. 1895, p. 221. This section has been obscure ever since I first saw it in 1897, and the brickfield is now abandoned. 32 UK. A. M. DAVIES ON THE KIMER1DSE CLAI [Feb. I907, It will be most convenient to describe these in descending order. 8. Zone of Exogyra virgula. — There can be no mistake about this zone, as specimens of the zone-fossil can be picked up by hundreds on the weathered surface. The majority are more or less broken, but a good number of perfect valves can be found, with occasionally a bivalved specimen. I have verified their occur- rence in situ in the uppermost 4 feet of clay, but it is not easy to collect except from the weathered surface : this may be the reason for the small number of species collected, as shown by the following list : — Ichthyosaurus (fragment of rib). Aptyclius lotus, Park. Exogyra virgula, Defr. Exogyra nana, Sow. Serpula convoluta, Goldf. Cytheridea ('!). Cristellaria, two species. Vagiaulina sp. 7. — The clay immediately below the virgula-zone is very similar lo the virgula-cl&y itself, but contains abundant crushed shells, among which Perisphmctes and Lucina were apparently recognizable. Verjr few other fossils were obtainable except microscopic forms, which abounded just at the base of the clay, immediately above Hie upper limestone-band. The following is the complete list : — Crinoid-ossicle. Echinoid-spine (minute). Xodosaria, two species. Vaginuliua sp. Cristellaria, two species. \ax sp. Vertebra of fish. Aptyckus lotus, Park. Perisphinctes (1). Lucina, (?). ' Ct/theridea ('.). Cytherella (?j. The upper portion of this clay was much obscured by slipping at "the times when I examined it. It contains some large septaria l near the top (unless these had slipped down from the virgula-zone, as is possible but not likely). The clay varies from grey to blue- grey in colour, has much 'race' in places, and elsewhere contains lenticular crystals of selenite, measuring from 0*5 mm. up to nearly 2 cm. in diameter. The lenticular form appears to be due to a combination of the hemipyramid (111) with what may be either the hemi-orthodome (103) or the hemipyramid (113), the cur- vature of this surface being so great that it is impossible to say whether it is one face or two. 6, 5, & 4. — The two limestone-bands are so exactly alike in character, that it is impossible to say from which of them any fossil was derived — the fossils having been either picked up among the broken pieces of stone or obtained from the workmen. A micro- scopic section of a piece of limestone shows nothing but a minutely- crystalline aggregate of calcite with flecks of brown (argillaceous) matter. A fragment dissolved in acid left a very fine argillaceous residue. 1 Mr. R>. W. Pocock has called my attention to the fact, that some of the crystals of calcite lining the fissures in these septaria exhibit the rhombo- .hedron impaled on the scalenohedron. Vol. 6$.~] AND COEALMAN ROCKS OF BRILL. 33 The following fossils were found in the limestone : — Pictonia cf. Cymodoce (d'Orb.). ? Olcostephanus Berryeri (Lesueur) — fragments seen. Pholadomya (squalls, Sow. Pleuromya recurva (Phil.). 3. — Below the limestones comes a thickness of about 8 feet of dark-grey, brown-weathering clay, with occasional, small, black and whitish-brown, phosphatic nodules, not exceeding 1 inch in greatest length. This clay yielded only a few fossils : — Ostrea (deltoidea ? Sow.^l, frag- Ostracoda. ments. Crislellaria sp. Serpula sp. ? Botalia. 2. — The selenitic clay which forms the lower part of the section is the most interesting division. It is a shaly black clay, weathering lilac-grey with sulphur-yellow stains, and showing a crumpled lamination. It contains abundant crystals of selenite, of all sizes from less than 5 millimetres up to about 20 centimetres in length. These are mostly the normal combination (010, 110, Til), untwinned, but a few show twinning, and a few show parallel growth tapering in one direction. Only in one place have I found a large mass of selenite (possibly an altered cement-stone) composed of lenticular crystals like those described on p. 32 from a higher horizon. In addition, selenite replaces, partly or completely, the calcite of the abundant belemnites and, very rarely, that of oysters. These latter fossils are abundant in an unaltered state. Such at least were the characters of this clay some years ago, and they can still be seen in parts of the brickfield ; but, with the cutting-back of the working-face farther into the hill, the selenite has diminished in amount, while instead are seen its antecedents in the form of crushed shells, ' race,' and (in washings examined with a lens) abundant granular aggregates of pyrites (probably marcasite) . The following fossils occur in this clay : — Reptilian bones. Belemnites abbreviates, Miller. Belemnites nitidus, Dollf. (= B. explanatus, Phil.). Gryphma dilatata, Sow. Ostrea deltoidea, Sow. Exogyra nana, Sow. Trigonia Voltzii, Ag. Protocardia sp. (crushed). Other crushed shells. The selenitization of the belemnites is a most interesting feature of this clay. The belemnite-guards, some of which exceed an inch in diameter, are usually changed completely into selenite, often with many small crystals projecting from the surface and obscuring the form, while the internal structure may be quite lost. In some cases, the selenite-crystals preserve the radiating arrangement of the original calcite ; and in parts of some specimens radii of unaltered calcite may be seen alternating with others of selenite. (PI. I, fig. 1.) In such cases, the concentric structure of the guard Q.J. G. S. No. 249. d 34 MR. A. M. DAVIES ON THE KIMERIDGE CLAY [Feb. I907, may also be shown by the sudden increase in the proportion of selenite beyond a certain circle. It would seem that the ferrous sulphate penetrated the guards along certain radial and concentric lines of weakness. No other recognizable fossils are, as a rule, selenitized. I have noted one case of Ostrea deltoidea thus altered, but in general the oysters are untouched. At various times, diggings have been made below the floor of the pit, for chimney-foundations and a reservoir. One of these, nearly 6 feet deep, I was able to examine. The greater part of the clay exposed was of similar character to that just described, full of small selenite-crystals ; but one band in it (of the precise level of which I have no note) was of a light-blue colour, free from selenite, and has yielded numerous microscopic fossils. Larger fossils also occurred, some phosphatized. At the bottom of this digging was a layer of argillaceous limestone ; and although I did not obtain any fossils from this, some were thrown out from probably the same limestone in a deeper digging. The full list of fossils from below the floor of the pit is as follows, those marked L being from the limestone : — Perisphinctes plicatilis (Sow.). Perisphinctes decipiens (Sow.) (L). Perisphinctes sp. Cardioceras cordatum (Sow.). Trigonia Juddiana, Lye. (L). Area sp. Pentacrinus (small ossicle). Crinoid-ossicle (minute). Echinoid-spine (minute). Cytheridea (1). Cristellaria. Pulvinulina (?). The most fossiliferous rock in the brickfield yet remains to be described, as, strange to say, its exact horizon is uncertain. This consists of a series of rounded masses or ' doggers ' of an impure limestone, the biggest of which are nearly 2 feet in diameter and 6 inches thick. These were all dug up prior to my first visit in 1899, and Mr. Uff informs me that none have been met with during the last seven years. They can only, therefore, have come from the selenitic clay, or from the lower part of the overlying grey clay, as those were alone exposed in 1899 ; and, as they are sometimes selenitic at the surface, they more probably come from the selenitic cla}'. It is remarkable that they should have been so abundant near the natural surface of the ground, and yet be wanting farther into the hill. The stone is extremely tough, and while such bivalves as Cyprina and Astarte easily come out when it is broken, such fossils as belemnites and oysters are usually inextricable. Fortunately, I have lately found some of the doggers that have been softened by long weathering, and from them have extracted fossils that can be seen in, but not removed from, the ordinary stone. By far the most abundant species are Serpula tetragona, Sow., and a little Cyprina. The following is the complete list of fossils identified : — Vol. es.] AND COKALLIAX ROCKS OF BRILL. 35 Cardioceras (Amoeboccras) alter- nans (von Bucb). Cardioceras excavatum (Sow.). Belemnites nitidus, Dollf. (with phragmocone). Cerithium? (very young). Pseudomelania ? (very young). Area sp. Astarte ovata, Smith. Astarte nionsbeliardensis (?) Contejean. Astarte cf. pidla, Roemer. Astarte, two otber species. Ci/prina cyreniformis (?) Blake. Lima sp. Modiola bipartite/,, Sow. Ostrea deltoidea, Sow. Ostrea cf. dubiensis, Contejean. Protocardia sp. Serpula tetragona, Sow. non, Ream. The serpulas are so abundant throughout the rock and so inex- tricable from it, that it is difficult to ascertain to what they can have been attached. In the weathered blocks already mentioned, they were attached to oysters and belemnites ; while oysters in turn had grown upon serpula?. The abundance of Sei-pida tetragona and Cyprina is a point of resemblance to the large doggers described by J. P. Blake1 from the Lower Kimeridge Clay of Woodhall Spa and Leavening, although the other fossils are not the same. When I first visited this section in 1899, only the selenitic clay, a, very little of the overlying clay with phosphatic nodules, and these serpulite-doggers were to be seen. The brickfield comes upon the mapped outcrop of ' Lower Calcareous Grit,' here described as represented by a clay with abundant Ostrea sandalina (Eceogyra nana). I fully expected, therefore, to find Ampthill Clay, and at first the evidence was all in favour of the selenitic clay being Ampthill Clay. Its intensely-selenitic character, the occurrence of phosphatic nodules at the base of the overlying clay, the association of Gryphcea dilatata with Ostrea deltoid ea, and of Belemnites abbreviatus with B. nitidus, are all points of agreement with the Ampthill Clay of Lincolnshire, as described by T. Roberts.2 In the course of time, however, evidence to the contrary has accumulated. jSone of the species found are exclusively Corallian, while the ammonite Cardioceras altemans (von Buch) is the zone-fossil of the Lower Kimeridgian. It is true that this ammonite has been recorded from the Upper Calcareous Grit of Yorkshire, but that may rather be a reason for including that formation, or part of it, in the Kimeridgian, than for admitting C. altemans as a Corallian fossil. It has, at any rate, never been recorded from the Ampthill Clay. Decisive evidence was provided by the two species of Trigonia — Tr. Juddiana and Tr. Voltzii (the latter, though only a fragment, showing the characteristic feature of growth-lines crossing the tubercles), both species exclusively Kimeridgian. As Tr. Juddiana came from 6 feet below the floor of the pit, we may safely say that nothing lower than Kimeridge Clay is exposed on Rid's Hill. The thickness of the Upper Kimeridge Clay here may be estimated at 50 feet, and that of the Lower Kimeridge Clay at not less than the same amount. If all the clay exposed in the brickfield is Lower Kimeridge Clay, 1 Quart. Journ. Geol. Soc. vol. xxxi (1875) p. 210. 2 Ibid. vol. xlv (1889) pp. 550 et seqq. d2 36 ME. A. M. DAVIES OX THE KTMEEIDGE CLAY [Feb. 1907, then the outcrop of Corallian shown on the geological map should be shifted farther north. There are reasons for thinking that it should probably also be broadened. For, if abundance of large specimens of GrypJicea dilatata marks the uppermost beds of the Oxford Clay, then those beds occur (1) at a pond by the roadside about halfway between Tittershall Wood and Wotton Park ; (2) in the Great Central Hallway-cutting a mile north of Wotton Station (where I also found Cardioceras vertebrate and Pecten jibrosus) : (3) at the little brickfield by Quaintou-Koad Junction (nearly half a mile north-west of Quainton-Road Station). All these points are about a mile north of the mapped upper boundary (a doubtful line) of the Oxford Clay, so that probably some of the mapped Oxford Clay is in reality Ampthill Clay. But direct evidence of Ampthill Clay is wanting. The cuttings on the Great Central (Prince's Pdsborough to Grendon Underwood) line, which might have afforded the necessary evidence, were sloped over before I visited them. In Ashendon cutting I picked up a specimen of Ostrea discoidea, Seeley ; but it may have been brought from else- where. In the cutting at Wotton Station I picked off the sloped sides some weathered-out fossils, namely : — Cardioceras cordatum (Sow.), young. I Exogyra nana, Sow. Belemnites hastatus, Blainr. Ostrea sp. Alectryonia gregaria (Sow.). Serpida sp. This list is more suggestive of Oxford Clay than of Ampthill Clay,, as Belemnites hastatus has not been recorded from the latter. One thing further has to be stated about the Kimeridge Clay. The microscopic examination of a large number of washings from different horizons has shown a complete absence of glauconite- grains ; an absence which is in striking contrast with the richly glauconitic character of the Portlandian rocks above. It is remark- able that the great Purbeck-Wealden episode of emergence should have been both preceded and followed by conditions favourable to the production of glauconite, while this was not the case with the minor shallow-water episodes of the Jurassic Period. In this con- nexion I have to correct a mistake, into which I fell a few years ago. In 1899 I exhibited at a meeting of this Society a specimen of richly-glauconitic rock from near WombwelTs Farm, Chilton, and described it as occurring in the Kimeridge Clay.1 I have now satisfied myself that it is really Lower Portlandian. Its association with a distinct feature along the western side of the valley led me to suppose it to crop out where it is found ; but more careful examination has convinced me that this feature is an old landslip. On the eastern side of the valley, where the dip is unfavourable to landslips, fragments of the same stone can be traced up to the level of the Portland Beds ; and in the recently-made railway- cutting at Haddenham, similar richly-glauconitic beds were exposed in the Portlandian.2 1 Quart. Journ. Geol. Soc. vol. lv (1899) p. lxxxvii. 2 Proc. Geol. Assoc, vol. xviii (1904) pp. 385-87. Vol. 6$.~] AND CORALLIAN ROCKS OP JBRILL. 37 III. The Arxgrove Stone (~R,haxella-Qe.vrt). The only well-marked Coralliau rock in the Brill district is one referred to thus by Phillips : — ' At Studley, near Oxford, Dr. Buckland detected a peculiar bed of clouded grey colour, and very tough and dense texture, a sort of argillaceous chert, rich in pinnae, ammonites, and other organic remains.'1 A. H. Green, in the Geological-Survey memoir, notes that ? this bed runs with a good escai*pment by Arngrove Farm to the north of Gravel-Pit Farm, beyond which point we lose sight of it altogether Immediately below this stone we find Oxford Clay with Gry^hcea dilatata, and it is therefore without doubt the bottom bed of the Calcareous Grit.' 2 He gives a good list of fossils from Arngrove Farm. Phillips, in his ' Geology of Oxford ' 1871, makes but slight allusion to this stone. He says: ' It [the Calcareous Grit] is indeed actually used on the roads at Studley* (p. 298) ; and he quotes a few fossils from that locality. Blake & Hudleston refer to it very briefly, remarking, after their description of the Corallian of Wheatley : — ' Professor Phillips has noticed, in his ' Geology of Oxford,' that the Lower Calcareous Grit forms what we may call an isolated sandbank at Studley, whence he has named some fossils ; but of the vast spread of this rock, marked in the Survey map between Holton and Brill, not a trace can be seen. No sand- pits or quarries are to be heard of ; and the whole soil indicates a stiff clay beneath.' 3 It is strange that the strongly-marked peculiarities of this rock have attracted so little attention. It is a thinly -bedded stone, broken up into roughly-rectangular blocks, sometimes as much as 4 inches square and 1| inches thick, but often smaller. Near the surface it becomes rubbly, almost gravelly in character. Its outcrop is marked at intervals by patches of uncultivated, furze-covered land, on which shallow pits have been opened, the stone being much used in the surrounding clay-land for flooring muddy places in the fields. The chief present diggings are near Arngrove Farm ; and as this is the only locality from which any abundance of fossils can be obtained, I have been accustomed to use the name Arngrove Stone as a convenient field-term for the rock. Without intending to put it forward as a permanent addition to stratigraphical nomenclature, I shall use it for convenience in this paper. When examined with a hand-lens, this stone is seen to be studded with innumerable minute ellipsoidal bodies, mostly of a translucent blue, but with everywhere some of an opaque white. On some surfaces these are seen to have disappeared, leaving empty spaces : and sometimes, on a joint-surface, they are seen in section, when a concentric structure can be detected. These bodies are embedded in a matrix of a grey colour and of brittle character, weathering to a light yellow-brown, and becoming very soft and friable. It is neither 1 • Manual of Geology ' 1855, p. 307. 2 l Geology of the Country round Banbury, &c.' (Sheet 45) 1864 p 44. 3 Quart. Journ. Geol. Soc. vol. xxxiii (1877) p. 311. 38 ME, A. M. DAVIES OX THE KIMERIEGE CLAY [Feb. 1907, calcareous nor purely argillaceous, although it adheres to the tougue. In one or two cases, small patches of actual grey clay replace the ordinary matrix, and in them the ellipsoids are scattered more loosely. The rock, as a "whole, is very light and porous, absorbing water very readily. These characters, taken together, enable fragments of the rock to be identified with the greatest ease. In one place only — at a pond-digging at the "Warren Farm, north of Studley l — this rock undergoes a remarkable change, becoming a limestone, though still exhibiting the characteristic structure. If we treat a piece of this limestone with acid, the great majority of the ellipsoidal grains dissolve, but a few of them, along with some argillaceous matter, remain as an insoluble residue. If some of the grains are removed from the ordinary Arngrove Stone and examined under the microscope, they are found to agree exactly in size and shape with the globate spicules of the tetractinellid sponge Rhaxella perforata, described by Dr. G. J. Hinde 2 from cherts in the Lower Calcareous Grit of Yorkshire. They are about •15 mm. in length, -1 mm. in sectional diameter, and occasionally show a distinct hilum. When they are mounted in glycerine (but not when in balsam) the regular quincuncial surface-marking can be detected under a high power, although in the blue spicules it is obscured by a coarser network-structure. Another, more striking difference between the blue and white spicules is, that between crossed nicols the former show first-order yellow interference- colours and an excentrically-radial structure, while the latter are practically isotropic. The examination of a thin slice shows that, in addition to the two kinds (or conditions) of spicules, there are also a few angular and subangular grains of quartz of the same order of magnitude. The proportion of ' blue ' spicules to ' white ' spicules to quartz-grains averages 9 to 3 to 1 in one slide. The ' blue ' spicules, when cut tangentially, show the irregular network-structure mentioned above. When cut centrally, they show (1) a narrow outermost zone, nearly clear and almost isotropic ; (2) within this, a dusky-brown zone, equally narrow, its inner margin showing cuspation, probably corresponding to the network apparent on the surface ; (3) a clear, glassy centre, forming the main bulk of the spicule. This last, on careful examination, often shows a faintly-marked agate-like structure ; and, between crossed nicols, a corresponding radiating chalcedonic structure is revealed. The radiation is sometimes fairly regular about the centre of the spicule ; at other times it is of a more complex type, with several centres ; or, aaain, the radii mav start from a point on the margin. (See PL I, fig. 2.) 1 This must not be confused with the (geologically more famous) Warren Farm near Stewkley, 17 miles to the east-north-east. Another Warren Farm, near Holton, -will be mentioned farther on (p. 4*J). 2 ' British Fossil Sponges' Monogr. Paheont. Soc. pt. iii (1893) pp. 210-12 & pi. xiii, figs. 7, 7 a-f; and Quart. Journ. Geol. Soc. vol. xlvi (1890) pp, 54-61 & pi. Yi. Vol. 6$.] AND COEALLIAN KOCKS OF BRILL. . 39 The ' white ' spicules, on the other hand, are more or less dusky throughout, and show by ordinary light a well-marked concentric and a less distinct radial structure : both structures being marked out by alternations of brown and clear material, although no part is so clear as the central mass of a ' blue ' spicule. The concentric layers show no cuspation. Between crossed nicols, they exhibit a regular radial structure in much duller tints than those of the ' blue ' spicules. The foregoing descriptions seem to indicate that the ' white ' spicules are in a less altered state than the ' blue,' and that the latter have either undergone recrystallization, or that all but their outermost shells have been dissolved away and the cavity so formed afterwards refilled by secondary chalcedony. This view obtains some confirmation from the structure of the calcareous variety of the stone, described below. The matrix in which the spicules and sand-grains are embedded is not easy to determine. In section, it varies from faint yellow to deep brown in colour, is speckled with brown (? limonite), and between crossed nicols shows a cryptocrystalline to amorphous structure. In the ' calcareous Arngrove Stone ' of Warren Farm the matrix is minutely-crystalline calcite, with cloudy impurities. The three constituent grains of the typical chert are now represented by (1) calcite-grains, (2) siliceous grains, and (3) sand-grains, as before. The first consist each of a single crystal or a small number of crystals of calcite, and can therefore be more easily understood as formed by the filling of a cavity than by true pseudomorphic replacement of chalcedony. The siliceous spicules (which can be examined whole in the insoluble residue of the rock as well as in section) differ from the ' white ' spicules of the chert by showing little or no concentric, though a fairly-distinct radial, structure, and by their perfect iso- tropism. They are probably, therefore, the globate spicules quite unaltered. The sand- grains are similar to those in the chert, and a few flakes of mica also occur. (See PI. I, fig. 3.) All the conditions in which the spicules of ffliaccella occur in these rocks were described long ago by Dr. Sorby x in the similar rocks of Yorkshire. I have not seen a specimen of the Yorkshire chert ; but the descriptions of it agree very closely with that of the Arngrove Stone, and the age of the two must be very nearly the same. We have already seen that, in describing this stone, Green (writing mainly from Mr. Polwhele's note) states that ' immediately below this stone we find Oxford Clay with Gryphcea dilatata, and it is therefore without doubt the bottom bed of the Calcareous Grit.'2 This statement probably refers to the escarpment of Pan's Hill, 1 Quart. Journ. Greol. Soc. vol. vii (1851) pp. 1-6. 2 ' G-eology of the Country round Banbury, &c.' Mem. Geol. Surv. 1864? p. 44. 40 ME. A. M. DAVIES ON THE EIMERIDGE CLAY [Feb. I907, where, just below the crest of the escarpment, large Gryphaeas are thrown out abundantly from the ditches. The precise relation of the Arngrove Stone to the Oxford Clay is shown by the following well-section, noted in September 1899. The exact site of the well is at the northern end of Studley village, by the side of the road to Boarstall, close to the 317-point on 6-inch sheet No. 26 (Buckinghamshire). The measurements are approximate, having been made by reference to the rungs of a ladder in the well : — Feet. 5. Soil and Arngrove Stone-rubble (outside the well) 3 4. Arngrove Stone 2 3. Reddish-brown sandy clay : fish-tooth, Alectryonia- fragments, traces of other shells 3 2. Argillaceous limestone less than 1 1. Clay, very black and stiff: Gryphcea dilatata, Cardio- ceras cordatum at least 10 19 From Studley, for more than 3 miles in a north-easterly direction, the Arngrove Stone forms a well-marked escarpment. This dies away rather suddenly at the main road from Oakley to Bicester, the last place where the Stone can be found being on a piece of waste ground on the north-east side of this road. All along this distance, for a varying breadth along the dip-slope, the chert is abundantly exposed in small diggings and in the soil of ploughed fields. Near Studley it is found on both sides of the Danes Brook, which trenches the dip-slope in the direction of the strike. So far, the well-defined boundary-line shown on the geological map between Oxford Clay and Lower Calcareous Grit is quite justified. But, farther to the east, all trace of the chert is quickly lost; and it is difficult to understand the grounds upon which the definite boundary-line has been continued up the valley to Boarstall, and again through Shabbington Wood and along the western side of the next valley, where only a broken line is drawn on its eastern side. Along the north side of Shabbington Wood, the soil is equally clayey on both sides of the mapped boundary-line ; and at one point, a little north- west of Shabbington- Wood Lodge, well within the area mapped as ' Lower Calcareous Grit,' a pond-digging shows clay with abundant large specimens of Gryphcea dilatata and Alectryonia yregaria. My own conclusions as to the extension of the Arngrove Stone are indicated in the sketch-map (fig. 2, p. 41). On the south-west, the continuation of the chert is abruptty cut off by denudation. Two miles away, across the broad valley of the Holton Brook and its tributaries, stand the normal Corallian rocks of Stanton St. John ; and it is natural to enquire whether any trace of the Arngrove Stone may be found intercalated in this series. Vol. 63.-] AND COBALLIAX BOCKS OF BRILL. 41 The only hint of its presence hitherto given is in the following sentence in the Geological-Survey Memoir : — ' Hence [from Stanton St. John] by Breach Farm the Calcareous Grit takes a stony form, showing as a hard sandstone with a calcareous cement, like the bed at Studley described below.' x Fig. 2. — Sketch-map of the outcrop of the Arngrove Stone (Bhaxella- chert) based on the Geological-Survey map. Sheet 45 S.E. 1 = Gravel-Pit Farm. 2=Boarstall. 3= Arngrove. [Scale: 1 inch = 1^ miles.] 4=Shabbington-Wood Lodge. 8=Bayswater Mill. 5=Beckley. 9— Holton Wood. 6=Woodperry. 10= Studley. 7= Stanton St. John. In reality, neither at Studley nor at Breach Farm is there a 4 hard sandstone with calcareous cement.' The stone-bed which forms the mapped base of the Lower Calcareous Grit near Breach Farm is quite typical Arngrove Stone. There is a good exposure Geology of the Country round Banbury, &c.' 1864, p. 44. 42 ME. A. M. DAVIES ON THE KIMEEIDGE CLAr [Feb. I907, of it in a ditch on the east side of Stanton Great Wood ; and from here I have been able to trace it almost continuously in both direc- tions, for a distance of quite 2 miles in all, by the abundance of its fragments in the brooks and ploughed fields. In the south-easterly direction, its last appearance is on the eastern side of Holton Wood ; in the other direction, it can be traced as far as the site of the old church at Woodperry ; and again it can be seen in the road-cutting a little beyond, where there is a considerable thickness of calcareous sandstone above it. Where it precisely dies away in this direction I cannot say, but there is no trace of it at Beckley Upper-Park Farm. Here, and round by Beckley Common to Stowood, the base of the Calcareous Grit is formed by a considerable thickness of reddish sands. The only other point where there seemed to be a prospect of finding it is above Bayswater Mill (fig. 2, no. 8, p. 41), in the valley of the Bayswater Brook, where the outcrop of Lower Calcareous Grit has been cut back to within nearly a mile of Stanton St. John. But here also the base is sandy, and I found no trace of Arngrove Stone. It must, therefore, thin away underground rather rapidly to the south-west of Stanton St. John. Along the greater part of this 2-mile outcrop, although no clear sections are seen, the overlying strata seem to be clayey. It is remarkable that, just where the chert dies away, the overlying strata become sandy. This is the case at both ends of the outcrop. At the south-eastern end, the sandy beds can be traced from Holton Wood, past Warren Farm, to near Pond Farm, fragments of iron- stone being abundant in the sandy soil between the two last-named places. Beyond this, it is difficult to find any evidence for the definite boundary drawn on the Geological-Survey map. Only at one point — at the pond near Ledall Cottage— is an obscure section showing coarse sand and ironstone, just at the mapped junction ; but both north and south of this point the soil is clayey, and large Gryphseas are thrown up in all ponds and other diggings. Fragments of ironstone are also common in the soil near Thomley Hill, and again 3 miles farther north, near Boarstall Wood. These occasional breaks in the great monotony of clay may be indications of Drift, rather than of intercalations in the solid strata; but the absence of clear exposures makes it very difficult to judge. What is clear is, that the Arngrove Stone extends over a much smaller area than that bounded by the unbroken boundary-line on the Geological-Survey map. Its actual outcrop and probable original area of deposit are indicated in the sketch-map (fig. 2, p. 41). The following is a list of the fossils collected from the Arngrove Stone, mainly at Arngrove itself. The species marked D 1 have found myself ; those marked S are added on the authority of the Geological-Survey Memoir and the specimens in the Jermyn-Street Museum ; those marked P are noted by Phillips. Many of the fossils are casts or impressions ; and, where the shell is preserved, the specimen is often incomplete through truncation by a joint-plane. Vol. 6$.-\ AND CORALLIAN ROCKS OF BRILL. 43 Cardioceras cordatum (Sow.) Cardioceras vertebrate (Sow.) Perisphinctes sp Alectryonia gregaria ? (Sow.) Area quadrisidcaia, Sow Area sp D Avicida inaquivalvis, Sow Avicula ovalis, Phill D Avicula sp D Exogyra nana, Sow D G oniomy u literata, Sow G-oniomya v-scripta, Sow j D Lucina crassa (?) Sow D ? ' Mactromya brevis, Ag.1 D Modiola bipartita, Sow ! D Modiola cuneata, Sow I ... Modiola imbricata, Sow Pecten fibrosus, Sow | D Pecten lens, Sow. ! D Pecten sp | D Pholadomya (squalls, Sow J D Pholadomya obsoleta, Phill ! Pholadomya sp ! Pinna lanceolata, Sow j D Pinna mitis, Phill i ... Pinna quadrata (1 Inoceramus) ; Pleuromya recurva (Phill.) j D Trigonia cla vellata (?J Sow ! D ? Cyprina i D ? Cardium i D ? Ceromya ! "D IModiola D Thracia or Anatinax ; ... Serpula sp j D Bhaxella perforata 0 ') Hinde (spicules)...) D 1 These two are probably the same species. IY. Pal^ontological Notes. Cyprina cyreniformis (?) Blake. 1876. Cyprina cyreniformis, J. P. Blake, Quart. Jotirn. Geol. Soc. vol. xxxi, p. 227 & pi. xii, fig. 6. Compare also — 1866. Cyprina pulcliella, P. de Loviol, Mem. Soc. Phys. Hist. Nat. Geneve, vol.xix, pp. 5-5-56 & pi. iv, figs. 10 a, 10 6, 11, 11a, 11 b. Cyprina semiparvula, nomen nudum, Etallon, P. de Loriol, op. cit. p. 56. This little bivalve is very abundant in the serpulite-doggers at Brill, just as Blake's species is at Woodhall Spa. It occurs in a perfect state of preservation, with the valves tightly closed, or as calcite- casts. Very rarely is a valve found single, and even then the extreme toughness of the matrix makes the complete exposure of the hinge-line impossible. It agrees well with Blake's description, but not with his figure (an external view of the right side), which shows the umbo as more anterior and the posterior part of the hinge-line as less sloping. s p s p s s s p s s p p s s s p s s p s p s s 44 MK. A. 3U". DAVIES ON THE KIMEELDGE CLAY [Feb. I907, It agrees very closely with C. pulchella, de Lor. (to which Blake refers as near to his species), in shape, dimensions, and . orna- mentation, but differs from it in two respects — (a) the umbones cannot be described as ' assez gros et renfles,' for they terminate in a fine point with a slight spiral ; (b) the angle at which the valve- margins meet is acute instead of being slightly obtuse. In com- paring his species with others near it, M. de Loriol remarks : — * La C. semiparvula, Etallon, non figuree, a des crochets termines en spirale distincte, ce qui n'existe point dans la C. pulchella? (Op. tit. p. 56.) This suggests the possibility that the Brill species may be the same as G. semiparvula, but I have not succeeded in finding Etallon's description. Blake, after comparing C. cyreniformis with C. tenuirostris, Etallon, remarks that * it is nearer still to Cyprina pulchella, de Loriol, but is more excentric and has not the anal side truncated.' (Op. tit. p. 227.) The Brill species is not more excentric, and the anal side, although I should not describe it as truncated, exactly resembles M. P. de Loriol's figures. The differences between these species are so slight that, without an examination of the type-specimens, I hesitate to name the Brill specimens definitely. The following are the dimensions of the three compared, Blake's measurements being translated, into millimetres and his proportions into decimals, for comparison with the others : — Brill : Four specimens. C. cyreniformis, Blake. C. pulchella, de Lor. Length 17 14-5 8-5. •85 •50 •41 16 12 9 •75 •56 13- 105 7-5 •80 •58 •38 11- 8-8 64- •80 •55 •39 17 13 l •75 •40 17 15 * 10 1 •88 •58 •41 Heigbt Thickness Height Length Thickness Length Proportion of ^ length an- j terior to f umbo. J 1 Calculated from the proportions given, to the nearest millimetre. [Through the kindness of Dr. Smith Woodward, I have had an opportunity of examining the Blake Collection, now in the Natural History Museum. The type of Cyprina cyreniformis does not appear to be present. — A. M. D., January 12th, 1907.'] AsTARTE, 5 Spp. No less than five species of Astarte occur in the serpulite- doggers at Brill. Of these, one is easily identified as A. ovata, Smith ; a Vol. 63.] AND COEALLIAN KOCKS OF BKILL. 45 second, a large species, is represented only by fragments, which fit well on to the figure of A. monsbeliardensis, Contejean, in respect of the closeness and curvature of the lines of growth. A third (referred to as species B below) agrees in dimensions withal, pulla, Eoemer, although the ornamentation does not seem quite the same. The two remaining species (A & C) I have not been able to match with any of the Upper Jurassic species, numerous though they be, described and figured by various authors. They certainly cannot be identified as Astarte supracorallina, d'Orb. The characters of these three species may be stated in tabular form thus, measurements being in millimetres : — Species A. Species B. Species C. 9-3 to 10 8-9 to 9-5 5-1 •96 to -99 •55 9 to 12 7-5 to 8 7 to 7-5 4 to 4*6 ? •92 to -94 •56? 6-5 to 7 10-4 to 11-7? 102? to 11-2? 5-6? to 6? •96? to -98? •51 ? to -54 ? 3 or 4 coarse and 9 fine. Height Thickness Height Length Thickness Length Number of concentric 1 ribs in a radius of 1 5 millimetres (where 1 farthest apart). J Lima semipunctata (?) Etallon. 1859-61. Lima semipunctata, J. Thurmann & A. Etallon, ' Lethsea Bruntrutana ' p. 244 & pi. xxxiii, fig. 7. The specimens of Lima in the serpulite-doggers of Brill are all very small, the largest not exceeding 8 millimetres in greatest length. They occur as internal casts, with only portions of the ears and hinge-line persisting. There is, consequently, nothing but the shape to identify them by, the casts being quite smooth. They agree in shape with Lima semipunctata, Etallon, and may well be the young of that species ; but might almost as well be the young of L. virgu- lina, Thurmann. Ostbea cf. dtibiensis, Contejean. 1859. Ostrea clubiensis, Ch. Contejean, ' Etude de l'Etage Kimmeridien dans les environs de Montbeliard & dans le Jura ' pp. 320-21 & pi. xxi, figs. 4-11. The recognizable oyster-shells in the serpulite-doggers at Brill (other than a single specimen of 0. dtltoidea, Sow.) resemble Contejean's species in all respects except size, their dimensions being about 50 per cent, greater. They cover much the same varieties of form, and show similar ornamentation and similar ligamental areas. This species has not been recorded from British strata. The nearest hitherto-recorded British species is 0. Soiverbyi, Morris & Lycett, from the Lower Oolites. From this species the present Length Height mm. = 12 = 12-2 Thickness = 9-3 46 MB. A. M. DAVIES ON THE XMEEIDGE CLAY [Feb. I907, one differs in the umbones being less obtuse and the posterior border less concave, while the form is more variable.1 Peotocaedia sp. This species occurs in a crushed and broken condition in the serpulite-doggers at Brill, only one specimen being fairly perfect. It differs from other Protocardiae of the same age, so far as I have ascertained, by the absence of concentric striaa and the larger number of the radial ribs, which are as many as 15 to 19, as against the usual 8 to 10. In some specimens the first six or eight of these ribs are finer than the rest ; in others they are not ; while, in one case, the second and fourth alone are finer. The ribbed area occupies about one-third of the length. The dimensions of the most perfect specimen are : — mm. Length Thickness Length = *'75 ? Macteomya bee vis, Agassiz. 1842-45. Louis Agassiz, ' Etudes critiques sur les Mollusques Fossiles : Mono- graphic des Myes ' p. 192 & pi. ix b, figs. 5-9. This species is probably the one identified in the Survey-list of Arngrove fossils as ' Thracia or Anatina.' It is fairly common in the Arngrove Stone, but, as it shows nothing beyond its form and ornamentation, it is extremely difficult to identify. Various genera of Anatinacea have species of very similar aspect, and so have several genera of Tellinacea. Among the latter, Isodonta Tcimmericli- ensis, Dollfus, resembles it most nearly ; but, in the Arngrove specimen, the posterior area is not quite so sharply defined, and the concentric striae are not so regularly spaced. The resemblance of form and markings to those of Mactromya brevis is much closer. Seeptjla teteagoxa, J. de C. Sow. 1829. Serpula tetragona, J. de C. Sowerby, ' Mineral Conehology ' vol. vi, p. 203 & pi. dxcix, figs. 1 & 2 (two varieties). Non 1839. Serpula tetragona, F. A. Roerner, ' Versteinerungen des Norddeutschen Oolithen-Gebirges ' Suppl. p. 19 & pi. xx, fig. 17. Allied species : — 1859. Serpula Thurmanni, Ch. Coutejean, 'Etude de l'Etage Kimmeridien dans les environs de Montbeliard & dans le Jura ' p. 227 & pi. xxv, figs. 13-15. 1873-74. Serpula Dollfussi, P. de Loriol, Mem. Soc. Phys. Hist. Nat. Geneve. vol. xxiii, pt. ii, p. 262 & pi. i, figs. 2 a-2 c. The abundant serpulae of the Brill doggers all seem to be refer- able to fig. 1 of Sowerby's S. tetragona. The best-preserved specimens show an ornamentation of obtusely V-shaped ridges, the point directed forwards, which is not indicated by Sowerby ; but, in all other respects, they agree with his figure and description. 1 [Dr. Kitchin has kindly called my attention to another species of Ostrea, nearly related to the Brill specimens. This is 0. hebridica, E. Forbes, Quart. Journ. G-eol. Soc. vol. vii, 1851, p. 110 & pi. v, figs. 4a-4c. — A. M. D., January 4th, 1907.] Vol. 63.~] AND COEALLIAN ROCKS OP BRILL. 47 Reamer's species is differently shaped in transverse section, being- trapezoidal instead of square, the attached face being the broadest and the upper face narrow and distinctly concave. S. Thurmanni, Contej., differs in the more strongly-carinate edges, smoother surface, and slightly-smaller size (diameter 1*5 mm. instead of 2 mm.). S. Dollfussi, de Lor., is decidedly smaller (diameter 1 mm.) and straighter than S. tetragona. It may be doubted whether these two forms should be regarded as distinct species, or whether they should not rather be considered as varieties of S. tetragona. Serpula. convoltjta, Goldfuss. 1826-33. Serpula convoluta, Goldfuss, ' Petrefacta Germanise' p. 228 & pi. lxvii, fig. 14. Non 1826-33. Serpula convoluta, Minister, Goldfuss, op. cit. p. 232 & pi. lxviii, fig. 17. This species does not appear in the lists of Jurassic fossils in the Geological-Survey Memoir on the Jurassic Rocks of Britain. It is, therefore, probably new to Britain. Five specimens were found, four of which were dextral and one sinistral. They agree closely with Goldfuss 's figures, which include both dextral and sinistral forms. Although Goldfuss's own species and Miinster's (both Jurassic) are described and figured very near together in the same book, under the same name, Bronn's ' Index Palaeontologicus ' (p. 1136) gives priority to Goldfuss's name. Bronn, however, identifies the species with Vermicularia nodus, Phillips.1 The rather unsatis- factory figure given by Phillips makes this identification possible, but V. nodus has been subsequently figured more carefully by Morris & Lycett,2 and it is certainly not the same as Goldfuss's species. The name Serpula convoluta. Goldfuss, should therefore stand. Occurrence. — Zone of Eocogyra virgula, Brill Brick & Tile Company's brickfield, at the foot of Rid's Hill, Brill (Bucks). [Specimens of Cyprina cyreniformis (?), Ostrea cf. dubiensis, and Serpula convoluta, from Brill, have been presented to the Museum of Practical Geology, Jermvn Street. — A. M. J)., January J$i, 1907.-] EXPLANATION OF PLATE I. Fig. 1. Thin transverse section of Belemnites abbreviates, Miller, Lower Kirneridge Clay, Brill ; showing the partial replacement of calcite by selenite. X 15. The unaltered calcite can be distinguished by the cleavage-cracks (see p. 33). Original in Dr. Cullis's Collection. 2. Thin section of Arngrove Stone (Ehaxella-Ghevt), Arngrove, Boar- stall (Buckinghamshire). X 40. The two varieties of spicules can easily be distinguished (see p. 38). 3. Thin section of the calcareous variety of Arngrove Stone, Warren Farm, Studley (Oxfordshire). X 40. (See p. 39.) i ' Geology of Yorkshire' 1829, p. 152 & pi. ix, fig. 34. 2 'Great Oolite Mollusca' Monogr. Palreont. Soc. pt. i (1850; p. 120 & pi. xiv, figs. 8 a-S b. 48 ME. A. M. DAVIES OS THE KIMEEID&E CLAY [Feb. I907, DlSCUSSIOX. Mr. H. B. Woodwaed congratulated the Author ou this con- tinuation of his careful researches from lower to higher portions of the Thame Yalley. Over most of the district now described the Geological Survey had recently been engaged, in order to prepare a map of the country around Oxford. The brickyard near Brill was just beyond the confines of this area, but he had examined it two years ago in company with Mr. Lamplugh, and together they had obtained from the lowest strata then exposed, the ammonite known as Cardioceras ecccavatum, GrypJiced dilatata, Ostrea dis- coidea, and Serpida tetragona. These fossils, indicative of the Ampthill Clay, had been identified by Mr. E. T. Newton, and the record might be taken to supplement the observations of the Author. "With regard to the Corallian area, Mr. T. I. Pocock had been engaged in mapping the region of Studley and Arngrove, while he (the speaker) had surveyed the ground near Wheatley and east- wards. The cherty rock had proved a useful horizon at the base of the Corallian in the northern region, and had been observed at Stanton St. John and farther south. Elsewhere to the east the boundary of Corallian Clay with Oxford Clay had been a matter of difficulty, as the strata and occasional fossils were displayed only in ditches and ponds. Although some modifications had been made in the original geological survey by Mr. T. R. Polwhele, the changes were made with the advantages of the labours of Blake & Hudle- ston and of the 6-inch maps ; and Mr. Polwhele's field-work and recognition of the clayey equivalents of the Corallian rocks were deserving of all commendation. Along the eastern boundary there was evidence, from well-sinkings, of bands of calcareous sandstone that had probably been decomposed along the outcrop. Alluding to the specimen exhibited, of Gryplicea dilatata with attached Ostrea deltoidea from the Kimeridge Clay near Brill, he remarked that, when these two came together, the bed in which they were found was usually regarded as Corallian. Might not the GrypJicea have been derived ? Prof. Hull said that he had listened with much interest to the paper, and felt gratified that the work of the Geological Survey in the Brill district had stood the test of the Author's examination. That work had been carried out by Mr. Polwhele, and was rendered specially difficult by the absence (except at the south-western corner of the sheet) of the Corallian Oolite. Thus two forma- tions of similar material (namely, bluish clay) were brought into immediate contact in a country where there were few sections, rendering it often impossible to decide where the boundary ought to be drawn. In the district of Oxford, west of that surveyed by Mr. Polwhele, the Corallian Oolite was sometimes present, as at Heading'ton Hill, but in other places absent. This was the" case in the south of the county near Earringdon, and here he had taken the line of the Great Western Railway as the hypothetical boundary between the Oxford and Kimeridge Clays, as the simplest and Quart. Journ. Geol. Soc. Vol. LXIII, Pl. I. 1x15 DIAMS. • «s - - >d.-:i^' >^--^ l}'*- ■■■;;. < ■ : - 1 yp ,a. ., 2 x 40 DIAMS. 3 x40 DIAMS. /. H. Pledge, Photomicro. Bemrose. Collo. BELEMNITES ABBREVIATUS AND VARIETIES OF ARNGROVE STONE, Vol. 6^.~] AND CORALLIAN ROCKS OP BRILL. 49 least open to objection — where no sections were exposed at the time. As regarded the cause of the occasional absence of the Corallian Oolite over some parts of Oxfordshire and adjoining districts, the speaker's view was that it was owing to denudation at the close of the Oxfordian Period, as the formation itself must be supposed to have been continuous over this region when originally deposited. Mr. Whitaker said that the specimens of selenite were inter- esting, especially those of Belernnites in which calcite had been replaced by that mineral. He had found a small specimen of the kind in the Oxford Clay of Buckinghamshire forty-nine years ago, and at a later date had seen many specimens in a pit in the Oxford Clay of the valley of the Ouse, several miles above Bedford, but had never before seen any from the Kimeridge Clay. There was some evidence, from wells, that a stony bed occurred (a little way underground) in the clay-tract southward of Brill ; and it might represent the Arngrove Stone of the Author, although this was very doubtful. The Author thanked the Fellows for their reception of his paper, and, in reply to Mr. H. B. Woodward, said that he was not prepared to admit the derived character of the Gryphaza clilatata to which Ostrea deltoidea was attached. Q.J.G.S. l^o. 249. 50 ME. E. W. HOOLEY ON THE SKULL AND [Feb. I907, 3. On the Skull and geeatee Poetion of the Skeleton of Gojstio- pholis cbassidens from the Wealden Shales of Atheefield (Isle of Wight). By Reginald Walter Hoolet, F.G.S. (Read November 21st, 1906.) [Plates II-IV.] I. HlSTOEY OF THE DlSCOVEET OF THE SPECIMEN. In the late autumn of 1904, at a place locally called ' Tie Pits/ near Atherfield Point (Isle of Wight), a large mass of the cliff, comprising many thousand tons of the Wealden Shales, subsided, pushing its foot across the beach, until below low-water line. As the sea washed away the base, the mass continued sinking, and fresh horizons were denuded. In 1905 a series of heavy ' ground-seas ' cast up blocks of limestone and ironstone, containing crocodile- bones, which were discovered on the sand, between high- and low- water marks. The skull came ashore in six pieces, and on as many different occasions. Scutes and fragments of bones were constantly picked up. One block found by a local fisherman was forwarded to the Sedgwick Museum, at Cambridge. After correspondence with Mr. Henry Keeping, the well-known Curator, I was put in communication with Prof. T. McK. Hughes, F.R.S., who, with great liberality and courtesy, wrote that in 'the interest of scientific progress' he thought that their block should be handed over to me, and this was accordingly done. The collection of the skull, etc. would have been impossible, but for the aid of Mr. Walter White, the coxswain of the Atherfield lifeboat, who obtained the separate portions by visiting the beach at every tide. The horizon whence the specimen was derived is 80 to 90 feet below the top of the Wealden Shales. II. HlSTOEY OF THE BRITISH GoNIOPHOLIDJ3. The genus Goniopholis was first founded in 1841 by Owen.1 The type-specimen, named by him Goniopholis crassidens, was obtained from the Purbeck Beds of Swanage, in 1837, by Robert Trotter, F.G.S., and presented by him to Mantell, whose collection is now in the possession of the British Museum (Natural History). It consists of the left mandibular ramus, teeth, scutes, vertebrae, and sundry bones of the pelvic region, lying on two slabs of Purbeck Limestone, one being the counterpart of the other. Mantell had previously, in the 3rd edition of his ' Wonders of Geology ' 1839, 2 made known and figured the fossil under the name of the ' Swanage Crocodile.' It was described again by him in the 1 ' Rep. Brit. Foss. Rept.' pt. ii, Rep. Brit. Assoc. 1841 (Plymouth) p. 69. 2 Vol. i, pp. 387-89 & pi. i. Yol. 63.~] SKELETON OF GONIOPHOLIS CRASSIDEXS. 51 2nd edition of his ' Medals of Creation,' * and in « Petrifactions, & their Teachings,' and in other of his works, while it was finally more fully described by Owen in 1878.2 In the Reptile Gallery of the Natural History Museum (Geological Department), the same frame contains, not only the two type-blocks, but a smaller one, with the impression of the orbital region of the skull and a fragment of the frontal bone, situate between the orbits ; and the impression and fragments of a moiety of the right ramus. This particular block was not referred to by Mantell or Owen. It is not mentioned in either of the works cited, nor is it noticed in the 'Catalogue of Fossil Reptilia & Amphibia' pt. i (1888), of the British Museum. When I mentioned this to Dr. A. Smith Woodward, he referred to Mantell's original manuscript-catalogue of his collection, where it is noted ; consequently, no doubt as to its belonging to the type-specimen can be entertained. Separate teeth are figured by Owen.3 He refers to, and figures, the greater portion of the premaxillae of Goniopholis, revealing the almost entire narial aperture, discovered by Mr. G. B. Holmes, of Horsham, in the Wealden of Cuckfield (Sussex). He ascribes this specimen to Goniopholis crassidens without stating reasons ; but, as no teeth are preserved and the premaxillae are unknown, it could alone have been suggested as belonging to that particular species, by the horizon from which it was derived. In the same supplement,4 Owen simply refers to fig. 5, pi. i, remarking that the specimen there figured was from the Purbeck Stone. It comprises the anterior ends of the rami, minus the splenials, now in the possession of the British Museum. This fossil is also referred to Goniopholis crassidens, because of its geological horizon. That this was the reason is made evident by his stating,5 in reference to three vertebras, that 'they were obtained by Mr. Holmes from the same bed of Wealden Clay, at Cuckfield, as the teeth and scutes figured in pi. iii, characteristic of the genus Goniopholis, to which, therefore, I refer them.' With these latter there were also preserved a caudal vertebra, coracoid, humerus, ilium, femur, and other bones. The preceding appear to be the only recorded remains of Gonio- pholis crassidens, and, excepting the isolated fragmentary moieties referred to that reptile by Owen, the skull was unknown. Another species, under the name of Goniopholis simus, was described by Owen6 from a skull, minus the lower jaw, from the Purbeck of Swanage. This particular specimen had been pre- viously described by Hulke,7 together with a skull and mandibles, acquired by Mr. Willett, from the Purbeck of Swanage, and 1 Vol. ii (1854) pp. 677-79. 2 ' Monograph of the Fossil Eeptilia of the Wealden & Purbeck Formations ' Suppl. viii (Palaeont. Soc. 1878) p. 1. 3 Ibid. pi. i. 4 Bid. p. 4. 5 Ibid p. 5. G Ibid. p. 7. 7 ' Note on Two Skulls from the Wealden & Purbeck Formations, &c.' Quart. Journ. Geol. Soc. vol. xxxiv (1878) pp. 377-81 & pi. xv. e2 52 ME. E. W. HOOLEY ON THE SETJLL AND [Feb. I907, ascribed by him to Goniopholis crassidens, but both skulls un- doubtedly belong to the species G. simus. There is a feature on the skull of the type-specimen which is not noted by either of these authors. A bony ridge, from the inner anterior border of the orbits, passes across the frontal bone in a curve, developing in the centre into a prominent eminence 6 mm. high, which in life must have been slightly higher, as the apex is gone. It is well defined, and has not been caused by crushing. On enquiry of Prof. Louis Dollo, I was informed by him that the skull of Goniopholis simus in the Musee Royal d'Histoire Naturelle de Belgique, at Brussels, shows no traces of the crest. However, this keel is found in Nannosuchus gracilidens as well, and is also not noted by Owen. It is interesting to observe that it is also present in the recent caimans and the North American alligator, but not iu any of the crocodiles that I have examined. Thus it appears in Caiman latirostris, sclerops, niger, latifrons, and Alligator mississip- piensis ; while it is absent in Crocodilus niloticus, palustris, porosus, rohustus, americanus, and in the gharials. In 1879 l Owen described another species under the name of Goniopholis tenuidens, from the anterior portion of a mandible, from the Middle Purbeck of Durleston Bay. He estimated the jaw of Goniopliolis crassidens to have measured about 2 feet in length, and G. tenuidens about a quarter of the size ; and he differ- entiated the latter from G. crassidens and from G. simus by this and the greater slenderness of the teeth. To four vertebrae, Owen gave the name of Goniopholis carinatus. He figured them,2 but gave no description. The fossils from which these four species of Goniopholis have been formed appear to be the only specimens from Britain that have been hitherto described. Through the kindness of Dr. A. Smith "Woodward, and Mr. E. J. Baily, of Battle (Sussex), who forwarded the specimen to the Natural History Museum, I have been enabled to study the skull of a Goniopholis, discovered by the latter gentleman in the Purbeck limestone near Battle. The skull is very much flattened, and portions of the upper jaw alone remain, much apparently having been destroyed at the moment of discovery. The premaxillse, as far as 13 mm. from the tip of the snout, are entire ; but there a small section is missing. The greater part of the maxillae and nasals, minus their posterior ends, are preserved. The prefrontals, lachrymals, and all other bones are absent, except the hinder portions of the frontal and postfrontal, and the anterior of the parietal. These latter, and the impress left on the matrix by what is lost, determine the supratemporal fossa to be subquadrate, and only slightly larger than the orbits. The articular ends of the quadrates remain. 1 ' Monograph of the Fossil Eeptilia of the Wealden & Purbeck Formations ' Suppl. ix (Palasont. Soc. 1879) p. 2 & pi. i. 5 ' British Fossil Eeptilia' 1849-84, vol. ii, pi. xiv. Vol. 63.J SKELETON OF GONIOPHOLIS CBASSIDENS. 53 The external nares are subterminal. Traces of bony prominences occur on the lateral borders of the nares. There are five alveoli on each premaxilla, twelve on the imperfect right maxilla, and fifteen on the left. Many of the teeth are preserved, and they all show the lateral carinas and the serrations characteristic of Goniopholis. Owen gives the difference in breadth to length of crown, as less in Goniopholis simus than in G. crassidens ; nevertheless, it is question- able whether the teeth are alone sufficient to distinguish one from the other, so similar are they. The sculpturing of the skull is similar to that seen in G. simus. The skull, from the articular end of the quadrate to the tip of the snout, measures 578 mm. (23 inches), which is a greater length than that of the type-skull of G. simus. The other measure- ments are in corresponding ratio. It was, therefore, an older or a more robust individual than the type, to which, considering the shape of the supratemporal fossae, the anterior nares and their subterminal character, the teeth, and the sculpture of the cranium, I have no hesitation in referring it. As is well known, the osteology of this species was made familiar by Prof. Louis Dollo in 1883,1 by means of the magnificent speci- mens obtained from the "Wealden of Bernissart. III. Description op the Athereield Specimen. The skull and bones discovered at Atherfield are remarkable for their well-preserved condition and lack of distortion. The skull is much as it was in life, and, if found in situ, would have been entire. The cranial roof is nearly square to the orbits, the snout moderately elongate, and the skull very depressed. Another prominent feature is its wedge-shape, there being a gentle rise from the nares to the posterior margin of the parietal. Laterally it gradually widens ; while the under margins of the mandibles sustain a nearly-horizontal line to the angle of the angular bone. Viewed from above, the general form is that of the broad-faced Procoelians, although, owing to the wide expansion of the cranial roof, the tapering appears more acute than it really is. The width between the upper temporal arches is much less than that of the lower. The upper and lower temporal arches and the parieto-squamosal bars are strong, but narrow. The interorbital space is wide. The posterior border of the skull, as it leaves the outer point of the squamosals, forms a deep crescent, the inner horn of which is on the parietal, a third of the distance from the parieto-squamosal suture. This is followed by a shorter and shallower crescent, with a corresponding larger crescent, to the opposite squamosal. The whole surface of the skull is magnificently sculptured with deep, more or less circular pits, without a free space or any bony 1 ' Premiere Note sur les Crocodiliens de Bernissart ' Bull. Mus. Boy. Hist. Nat. Belg. vol. ii 1883) p. 309. 54 ME. E. W. HOOLEY OX THE SKULL A2sTD [Feb. I907, keels or prominences. There is a deep and large depression immediately in front of each orbit, and situated on the maxillae. The nasals (PI. II, a) apparently just reach the anterior nares. Rapidly expanding to a width of 57 millimetres, they quickly con- tract to 50 mm. from these openings. From here they gradually widen, till they meet the prefrontals and frontal, when they taper into attenuated points. The maxillae (PL II, 5), broad and deeply festooned, resemble those ot the recent crocodiles. The lachrymals (PI. II, c) are large. On their hinder ex- tremities are two strong ridges, converging forward and divided by a deep groove, forming the anterior boundary of the sockets. The prefrontals (PI. II, d) are small. Their outer posterior edges take a share in the orbital rim. The frontal (PI. II, e) is quadradiate, a long posterior ray uniting with the parietal, and shorter rays with the postfrontals ; these also bend forward, and form a small section of the orbits. A broad anterior ray meets the prefrontals and nasals. The postfrontals (PI. II, /) are stirrup -shaped, the spur meeting the squamosal, and the branches comprising the posterior boundar}'of the orbits, the outer being the longer, reaching the jugals and completely bounding the sockets from the infratemporal fossa. The squamosals (PI. II, g) and the parietal (PI. II, li) are near in shape to the similar boues in the Procoelians, but the greater extent of the supratemporal fossae causes them to throw out longer branches. The jugals (PI. II, i) complete the orbits. From here to their union with the quadrato-jugal they are long, slender, rod- like bones, with a slight median bend similar to that seen in the Teleosaurs. The quadrato-jugals (PI. II, j) are also narrow, and carry on the bar, made by the jugals, to their union with the quadrate. The quadrates are not well displayed. The articular end of the right has been destroyed by the sea, and the left is buried in matrix and hidden by other bones. The supraoccipitals are covered by the atlas and axis, and by the matrix. Portions of the exoccipitals are to be seen, on each side of the foramen magnum. The outer branch of the left is also visible. It resembles the same moiety as in the recent crocodiles, with perhaps a broader ledge for muscle-attachment. The occipital condyle (PL III, cZ), compared with the size of the skull, is small, and has no median groove. The basioccipital has a very broad longitudinal ridge, from the condyle to the median eustachian tube. The contour of the external nares (PL II, Jc) cannot be determined, for the premaxillae have been broken off, excepting a small portion which comprises the termination of the nasal floor, and a fragment of the posterior extremity of both the right and the left. These suggest that they were not subterminal as in Goniojpholis simus, and that the nasals just entered their posterior Vol. 63J] SKELETON OE GONIOPHOLIS CBASSID&NS. 55 border; also that the premaxillae described by Owen l do really belong to Goniopholis erassidens. The orbits (PI. II, I) are ovoid. Their posterior borders are high. Laterally they gradually decline on to the lachrymals. Here a deep and wide groove divides them. Prom the bottom of this groove to the summit of the supraorbital rim there is a vertical elevation of 49 millimetres (2 inches). Any other than a forward vision was precluded. The type- skull of GoniopJiolis simus is so flattened by pressure, and the boundaries of the orbits so much destroyed, that it is impossible to say how near in this respect they approached to those of the skull under consideration ; and Prof. Dollo does not refer to this in his previously-mentioned description of the Bernissart specimens. The supratemporal fossae (PL II, m) are very large, almost twice the size of the orbits. Their inner and posterior margins form curves, while their outer and anterior margins are nearly straight, forming a right angle at their junction. The lateral temporal fossae (PI. IY, fig. 1, ct) are large, as is also the tympanic cavity (PI. IY, fig. 2, a). These fossae are divided by a postfrontal and jugal bar. The orbits apparently do not communicate with them. The palatines (PI. Ill, a) continue with nearly the same width as when they leave the pterygoids, to half their length. Here they expand, meeting the maxillae 31 mm. from the front extremity of the palatal fossae. Their posterior extremities form only the extreme anterior boundary of the posterior nares, for they immediately connect with, and become exterior to, a process thrown out by the pterygoids. The pterygoids (PI. Ill, 6) have their posterior borders much damaged. They appear to widen gently from their median suture, to their contact with the mandibles. Here they have a short expansion, then curve inwards to the palato-pterygoid vacuity. Anteriorly, they throw out a process which forms the lateral borders of the nares, and outwardly a portion of the margins of the palatal fossae. The transpalatines (PI. Ill, c) sweep round from the ptery- goids to the maxillae, narrowing the hinder breadth of the palatal vacuities. Their surface on their inner and outer moieties is concave, and convex on the median. The posterior nares (PI. Ill, /) are divided by a pterygoid septum, and are twice as long as wide. The palatines border only their extreme anterior point, the pterygoids forming the remainder of their margins. The median eustachian canal (PI. Ill, g) is large. It is situated wholly on the pterygoid plane, very near to the posterior nares. The palato-pterygoid vacuities (PI. Ill, e) are long and oval, with their posterior end contracted by the inward curve of the transpalatine bone. 1 ' Monograph of the Fossil Reptilia of the Wealden & Purbeck Formations ' Suppl. viii (Palseont. Soc. 1878) p. 4 & pi. i. 56 ME, E. W. HOOLEY ON THE SXTJLL AND [Peb. I907, The maxillo-palatine suture leaves the palatine suture at right angles, and at a distance of 30 millimetres from it turns sharply, keeping a straight line parallel with the latter, until near the palatal vacuity, where it doubles back at an acute angle, and immediately enters the vacuity. The premaxillo-maxillary suture is hidden by the sym- physial extremity of the mandibles. The mandibles (PI. IV, fig. 1, c) are long and slender. They have no vacuity. The incisary region is well raised, and sinks rapidly to the laniary. There is no, or only a slight, elevation in the median region of the alveolar tract ; they rise without further undulation to their articular end. The alveolar tract extends probably some 288 millimetres (11-33 inches). The symphysis is short. The mandibles at this end are heavy and broad, their outer margins being very square. At almost regular intervals up either side of the symphysis are a series of pits in line, and deeper than any in the immediate area. The splenials (PL III, i) enter well into the symphysis. There are only two teeth preserved, both in the hinder region of the maxillae, one in the right, the other in the left. They are both small. They have the characteristic ridges and well-developed carinae, laterally, midway between the concave and convex sides. As the mandibles are firmly fixed against the upper jaw, and the line of junction is filled in by matrix and pyrites, the dental formulae cannot be ascertained. The alveoli that are visible prove the teeth to have been very unequal in size, and the upper overbit those of the lower jaw. The atlas and axis vertebrae (PI. II, o &_p) are cemented by the matrix and pyrites to the occipital region of the skull, above the condyle. The neural arch of the atlas and the distal ends of the floating ribs are preserved, but they cannot be fully exposed without damage. The odontoid bone is united to the centrum of the axis. Com- pared with the latter, it is large. Its anterior articular surface is slightly convex. At this end it has a strong broad ridge, laterally and ventrally. The centrum of the axis is small. The neural spine of the axis is missing. Both the atlas and the axis vary little from those of recent crocodiles. Pour more or less perfect cervical ribs are also embedded here. The third cervical vertebra (PI. IV, fig. 2, 6) is lying in the matrix in the pelvic region. The fourth, fifth, sixth, and portion of the seventh cervicals (PI. IV, fig. 1, d-g), and the proximal ends of their ribs, are contained in a small block of rock, showing a recent fracture posteriorly. The next block has a similar face anteriorly. The portion that filled the gap has not been recovered. On this block, and on three others all exactly fitting on to each other, are a part of the sixth, the seventh, eighth, ninth, tenth, and eleventh dorsal1 (PI. IV, 1 The number of cervical and dorsal vertebrae is here taken to be equal to the number of the corresponding vertebrae in Goniopholis simus. Vol. 63J SKELETON OF GONIOPHOLTS CRASSIDENS. 57 fig. 2, c), four lumbar (PL IV, fig. 2, d), and the first sacral (PL IV, fig. 2, e) vertebrae, in consecutive series, many sternal and abdominal splint ribs, the left coracoid, the left humerus, the right and a moiety of the left ilium, right ischium, and the two femurs. All the vertebrae are amphiccelous, otherwise they approach in form closely to those of the recent crocodiles. The neurocentral suture rises from behind forward in the cervical. It is convex in the dorsal and lumbar, while in the first sacral it is sigmoid. There are eight right thoracic vertebral ribs (PL IV, fig. 1, h) and four left, more or less perfect. Many of the cartilaginous sternal ribs lie scattered in the matrix between the vertebral ribs, some being well exposed. Four of the abdominal splint ribs (PL IV, fig. 1, j ) are preserved. The coracoid (PL IY, fig. 2,g) is very elongate. It has a slight expansion at its ventral end. The humerus (PL IV. fig. 2, h) is a very powerful bone. The deltoid ridge is not displayed. It is 25 millimetres shorter than the femur. Owen r gives further particulars of this bone. Embedded in the matrix on the right of the skull, under the squamosal, lie the distal ends of the radius and ulna, and(?)the radiale and ulnare. There is a portion of the shaft of a limb-bone visible in the left supratemporal fossa, as it passes from the base of the skull towards the left orbit. The ilium (PL IY, fig. 1, Jc) has the pre- ace tabular portion short, and the post-acetabular very long and strongly curved. Owen describes it (op. cit. p. 3) as being ' broader than in the existing Crocodilians.' The acetabular region is a shallow concavity, with plenty of space for the play of the femur. On the summit of the crest the bone is considerably thickened, and the spinous process very highly developed. The ischium (PL IY, fig. 2, i) is short. Proximally it is much bifurcated. Its distal end is moderately broad. The distal end of one of the pubic bones has alone been recovered. The femur (PL IY, figs. 1 & 2, m &j) has the usual Crocodilian characters, with the inner portion of the proximal condyle and the median trochanter more strongly developed. Twenty consecutive right dorsal scutes (PL IV, fig. 1, p) and several of the median ends of the left lie in the natural position. Two of the scutes on the right show well the characteristic pegs. There are also nine scutes of the ventral buckler, joined by their sutures. Numerous dorsal, ventral, and other scutes are scattered throughout the matrix. They call for no detailed description, as their characters are well known. The portion of the axial skeleton obtained, that is, from the tip of the mandibles to the posterior end of the first sacral, measures 1*505 metres (4 feet 11 J inches) ; and, if we allow for the missing cervical and dorsal vertebrae 1*930 metres (6 feet 4 inches), the total length of the reptile must have been about 3 \ metres (11| feet). 1 * Monograph of the Fossil Eeptilia of the Wealden & Purbeck Formations ' Suppl. viii (Palaeont. Soc. 1878) p. 5. 58 MR,. E. \V, H00LEY ON THE SKULL AND [Feb. I907, IY. Agreement of the Atheefield Fossil with the Type- Specimen OF GONIOPHOLIS CRASSIDENS. As previously noted, the impression of the skull on the slab containing the type-remains had never been described. Further, it has been seen that the known portions of the skull of Goniopholis crassidens consist of teeth and part of the left mandibular ramus ; for the fragments of the mandibles described and figured by Owen were, as before stated, apparently referred to this species because they were discovered on the same geological horizon. With the ramus, teeth, and odd bones of the type, the Atherfield fossil agrees. The impression of the cranial surface on Hantell's slab begins near the position of the parieto -frontal suture, and embraces the outline of the anterior moiety of the left supratemporal fossa and portions of the pre-frontals, lachrymals, nasals, and maxillae. No trace of the sutures of these bones is to be found, and so their form cannot be determined. The anterior outline of the orbits can be fairly judged. So far as can be ascertained, the orbits longitudinally and trans- versely, and the measurements of the impression of the left inner anterior corner of the left supratemporal fossa, agree with the Atherfield skull. The sculpturing, the contours of the orbits, the slightly-concave interorbital space, and its elevation as it nears the orbital rim, likewise are close to that of the Atherfield cranium. With the impression was a fragment of bone, across the inter- orbital tract, near the position where the keel noted in Goniopholis simus occurs. It seemed possible that its presence might be due to a similar ridge having given an extra grip on the matrix. On my calling Dr. A. Smith Woodward's attention to this possi- bility, he deemed it important enough to have the fragment removed, with the result that no keel was discovered, but a concave pitted surface as in the Atherfield skull. From these considerations I have no hesitation in assigning the Atherfield remains to Goniopholis crassidens. That being so, I shall endeavour to demonstrate that the skull of G. crassidens differs in many important particulars from that of G. simus and other Gronio- pholidse, and hereafter shall refer to it as Goniopholis crassidens. V. COMPARISONS BETWEEN THE SKULLS OF GONIOPHOLIS CRASSIDENS AND G. SIMUS. (1) In its dimensions the skull of G. crassidens is a third greater than that of G. simus. The general outline is similar. (2) In G. crassidens the supratemporal fossae are twice the size of the orbits, in G. simus only slightly larger. (3) In G. crassidens they are subcircular, but subquadrate in G. simus. (4) Deep pre-orbital depressions exist on the maxillse of G. cras- sidens; mere traces in G. simus. Vol. 6^.~] SKELETON OE GOKIOPHOLIS CRASSIDENS. 59 (5) The lateral temporal fossae and tympanic cavity are greater in G. crassidens than in G. simus. (6) Absence of an inter-orbital ridge in G. crassidens ; its presence in G. simus. (7) The nasals, anteriorly, in G> crassidens widen till near the constriction, whence they quickly converge to the anterior nares, the posterior border of which is apparently reached. In G. simus they do not broaden, and on reaching the premaxillse rapidly con- tract to an acute point 27 millimetres from the anterior nares. (8) In G. crassidens, the hinder extremities of the premaxillse are very blunt, and probably do not extend 29 mm. beyond the anterior nares. In G. simus they are very sharp, terminating where the nasals begin to narrow, 70 mm. from the anterior nasal opening. (9) In G. crassidens the surface of the skull is deeply and uni- formly pitted, without any other sculpturing. In G. simus it is neither so uniformly nor so deeply pitted. Moreover, the nasals have a crinkled surface anteriorly and posteriorly, and are almost free from pits, and those that occur are very shallow. The frontal is also crinkled at its juncture with the nasals, while behind this to the orbits it is quite smooth and free from ornamentation. (10) In G. crassidens the posterior nares are twice as long as they are wide, and, except their extreme anterior margins, are entirely formed by the pterygoids. In G. simus they are narrower, and a third of their border is formed by the palatines. (11) The form of the palatines reveals a remarkable dissimilarity. In G. crassidens the pterygo-palatine suture rises acutely from the posterior end of the suture connecting the palatines to the palatal fossa. In G. simus it is nearly horizontal, with a crenated contour. In G. crassidens the lateral margins are almost parallel, only slightly expanding as they approach the maxillae. In G. simus they soon commence to dilate, and continue to widen to the maxillo- alveolar border. In G. crassidens, the palato-maxillary suture leaves the palatal median suture at right angles, and, keeping horizontal for 31 mm., turns at a right angle, parallel with the median suture until near the pterygo-palatal vacuity, where it doubles back at an acute angle into that fossa. In G. simus the course of this suture is quite different. Owen r thus describes it : — ' The palato-maxillary suture is strongly sigmoid, describing as it leaves the mid-line a convexity forward, then a concavity.' In addition to these differences in the skulls, the dimensions of GoniophoUs crassidens are one-third greater than those of G. simus. 1 ' Monograph of the Fossil Eeptilia of the Wealden & Purbeck Formations ' Suppl. viii (Pakeont. Soc. 1878) p. 8. 60 MR. E. W. HOOLET ON THE SKULL AND [Feb. 1 0,0 7, YI. Comparisons with Gokiopholis tenuidens, Naknosuchus, AND OWEJSTIASUCHUS. Goniopholis tenuidens (Owen). The anterior end of the mandibles is the only portion of the skull that is known ; this reveals no agreement with the same moiety in G. crassidens. It differs by its : (1) Much smaller size and by the contour of the alveolar tract. (2) The high elevation of the incisary and median regions of the alveolar tract, and its deep laniary concavity. (3) The sharp and more slender teeth. The Genus Nannosuchus (Owen). Agrees in : (1) The general form of the skull. (2) The articulation of the dorsal scutes. Differs in : (1) The small size of the skull. (2) The shape of the supratemporal fossa?. (3) The relative magnitude of the orbits to the supratemporal fossae. (4) The outline of the posterior border of the skull formed by the parieto-squamosal bar. (5) The presence of an interorbital ridge. (6) The presence of a supraorbital bone. (7) The form and length of the nasals and their non-entrance into the nares. (8) The recurved slender teeth. (9) The form of the dorsal scutes. The Genus Oweniasuchus (A. Smith Woodward). Agrees in : (1) Mandibles similar in form, and their deeply-reticulated posterior external surface. (2) The absence of a mandibular vacuity. (3) The very slight laniary concavity. Differs in : The short extent of the alveolar tract. Vol. 63.] SKELETON OF GONIOPHOLTS CRASSIDENS. 61 VII. Measurements of the Type-Skulls of GONIOPHOLIS CRASSIDENS AND G. SIMUS, IN MILLIMETRES. G. crassidens. G. simtis. Length, articular end of quadrate to tip of snout 415 Length, occipital condyle to tip of symphysis 544 Breadth between extreme outer points of squamosals ... 205 149 Breadth of roof across posterior border of supra- temporal fossae 258 Do., anterior border 230 Breadth between inferior-temporal arcades, across pos- terior border of supratemporal fosste 339 Breadth across anterior points of orbits 196 Breadth between festoons 159 Breadth between constrictions 64 Longitudinal diameter of supratemporal fossae 90 44 Transverse do 90 40 Longitudinal diameter of orbits 67 46 Transverse do 49 33 Longitudinal diameter of posterior nares 50 44 Transverse do 25 8 Longitudinal diameter of palatal fossae 197 Transverse do 70 Length from angle of angular bone to tip of symphysis... 597 Breadth of mandibles across posterior end of posterior nares 330 Do., posterior end of symphysis 108 Greatest breadth of symphysial end of mandibles 142 Length of symphysis 85 Length along which splenials merge into symphysis 35 Where the measurements are not stated, this omission is because the corresponding portions of the skulls are either too badly pre- served for accuracy, or are missing. VIII. Measurements of the more important Bones of the Skeleton of G. crassidens, in millimetres. Antero-posterior diameter of odontoid bone 25 Dorso-ventral do 49 Antero-posterior diameter of centrum of axis 48 Dorso-ventral do 30 Length of coracoid 180 Length of humerus 280 Length of ilium 207 Length of ischium 135 Breadth of proximal end of ischium 70 Breadth of distal end of ischium 105 Length of femur 305 IX. Concluding Remarks. In conclusion, I would observe that we have here a crocodile in which the vertical elevation of the orbits is greatly more accen- tuated than in the Teleosaurs or other Amphicoelians, and very far removed from the everted orbits of the Procoelians. Their direct 62 3IE. E. W. HOOLEY ON THE SKULL AND [Feb. I907, frontal aspect curtailed the arc of vision, and it would seem that the creature's prey, or foes, were in an unobserved position when once behind the orbits. In the greater length of the femur than of the humerus, and the deep depression on the hinder extremities of the maxillae, which are evidently the vestiges of preorbital vacuities, Goniopholis crassidens is nearer the Teleosaurs than G. simus, but is farther removed than the latter from them in the position of the posterior nares. Considering the massiveness of the head, and the weight which its heavy armour must have given to the body, the length and slenderness of the mandibles is remarkable. It is surprising how they withstood the strain occasioned in a combat with, or the capture of, the creature's more powerful congeners. The reptile was capable of a gape of over a metre. The presence of the interorbital keel, found in all the American alligators, is probably the developed trait peculiar to a line descended from the Goniopholidse. My thanks are due to Dr. A. Smith Woodward, E.R.S., for much kindness and help in the preparation of this paper. EXPLANATION OP PLATES II-IV. Plate II. Dorsal aspect of the skull of Goniopholis crassidens. ^ nat. size. a = nasals ; b = maxilla ; c = lachrymal ; d — prefrontal ; e = frontal ; f= postfrontal ; g = squamosal ; h = parietal ; i = jugal ; j = quadrato- jugal; k — nasal passage; £ = orbit; m = supratemporal fossa; n= right mandibular ramus ; 0 = atlas ; p = axis ; £=lst& 2nd right cervical ribs : r = distal end of ulna ; s = distal end of radius. Plate III. Ventral aspect of the same. ^ nat. size. a=palatine ; 6=pterygoid ; c=transpalatine ; cZ=occipital condyle; e=palato- pterygoid vacuity ; / = posterior nares ; g = median eustachian canal ; /i=dentary ; i =splenial ; j = angular. Plate IV. Pig. 1. — Eight lateral aspect of the skeleton of Goniopholis crassidens. Yq nat. size. a=lateral temporal fossa ; b = jugal and quadrato-jugal bar ; c = mandible : d = 4th cervical vertebra ; e = 5th cervical vertebra ; / = 6th cervical vertebra; g = portion of 7th cervical vertebra ; h = vertebral ribs ; i == sternal ribs ; j = abdominal splint ribs k = ilium ; I = ischium ; m = femur ; n = proximal end of tibia ; 0 = distal end of tibia ; p = dorsal scutes ; q = ventral scutes. Eig. 2. — Left lateral aspect of the same, yq nat. size. a = external auditory meatus ; b = 3rd cervical vertebra ; c = dorsal ver- tebras ; d = lumbar vertebras ; e = 1st sacral vertebra; /= sternal ribs ; g — coracoid ; h = humerus ; i = ischium ; j = femur ; k = cervical scutes. Quart. Journ. Geol. Soc. Vol. LXIII, Pl.II R.W.H.% Photo. Bemrose, Collo. DORSAL ASPECT OF CRANIUM OF GONIOPHOLIS CRASSIDENS. Quart. Journ. Geol. Soc. Vol. LXIII, Pl. III. f"' i nat. size. R.W.H., Photo. Stmrose, Collo. VENTRAL ASPECT OF CRANIUM OF GONIOPHOLIS CRASSIDENS. Yol. 6s.~] SKELETON OF GOXIOPHOLIS CBASSIDEKS. 63 ' . Discussion. Dr. Smith Woodward congratulated the Author ou his first contribution to the Society's Proceedings. -It was an illustration of the importance of local collectors for the progress of Palaeontology. Although the remains of Goniopholis crassidens were among the commonest of Wealden fossils, the precise characters of the species had remained unknown, until the discovery which the Author had now described. The new observations were of all the greater value, because the Goniopholidee represented an entirely-new departure in the evolution of the Crocodilia at the end of the Jurassic Period ; and biologists needed an exact knowledge of the skeleton of these reptiles, before they could discuss the meaning of the development in question. The late Sir Richard Owen thought that the first appearance of alligator-shaped crocodiles, such as Goniopholis, was correlated with the incoming of warm-blooded quadrupeds and birds, which would form a new kind of prey. Mr. E. T. Newton remarked on the interest of this specimen, in that it supplied for the first time the skull of Goniopholis crassidens, which species had. been established chiefly on the peculiar form of the scutes. The skulls that Hulke had described in 1878, one of which he thought might belong to G. crassidens, were now shown to be quite different, and would both be included in the species G. simus, one of them having been so named by Owen. He alluded to the fact (first recognized by Huxley, and later on by Hulke) that the position of the posterior nares, far back upon the palate, in these Wealdeu crocodiles was an intermediate one between those of the Lower Jurassic crocodilians, in which these openings were farther forward, and those of the Tertiary croco- dilians, where, by the closing-over of the pterygoids, the nares came to be placed on the hinder aspect of the skull, as in recent crocodiles. Dr. C. W. Andrews congratulated the Author, both on his good fortune in finding such valuable material, and on the paper that he had read. The chief interest of the specimen described seems to be that it completes our knowledge of Goniopholis crassidens, and shows that that species is in several respects intermediate between G. simus and the modern Crocodilia. Indeed, some of the characters distinguishing it from G. simus seem to be of sufficient importance to justify the separation of the latter species as a distinct genus. The Author, in reply, said that he agreed with the last speaker that the characters of the nasals, palatines, and supratemporal fossse were perhaps sufficient to separate the other described species from the genus Goniopholis ; but, as the teeth of all the specimens agreed in possessing serrations and lateral carinas — the characters laid down by Owen, he thought that it was better to leave them as they were for the present, rather than to multiply genera. The Author returned thanks for all the kind remarks that had been made in regard to his paper and his work. 64 MB. 0. H. EVAXS OIST THE [Feb. I907, 4. ^sotes on tlie Raised Beaches of Taltal (Noetheex Chile). By Oswald Haedey Evans, P.Gr.S. (Eead December 5th, 1906.) It is well known that the coast of Western South America presents, practically throughout its entire length, phenomena usually con- sidered as being evidences of recent elevation, and the researches of Darwin long ago rendered familiar the shell-beds and terraces of Coquimbo, Huasco, Caldera, and other localities on the Chilian sea- board. Between Caldera and Iquique, however, the coast-phenomena have had little more than passing references bestowed upon them, the minor settlements of the Atacama Desert being seldom visited by travellers until of late years. At Iquique, Darwin l found shells at a height estimated between 150 and 200 feet, and A. d'Orbigny 2 observed recent shells in Cobija at 300 feet above sea-level. David Forbes 3 states that, between Mexillones and Arica, the evidences of elevation above 40 feet are unsatisfactory. During a residence of two years at Taltal, I devoted much of my leisure to the study of the geology of the district. In communi- cating the following observations on the raised beaches, I have to mention with regret the entire loss of all my notes and photograpbs and practically the whole of my collection of fossils, in the Valparaiso earthquake of August 16th, 1906. Having, therefore, to depend almost entirely upon memory, I have been careful to confine myself to statements which I know to be correct, but am nevertheless fully conscious of the imperfection of the paper necessarily resulting from the lack of my original notes. The town of Taltal, formerly insignificant but becoming daily of more importance as a port for shipping nitrate, is situated at the head of a small bay formed by the rugged hills and reefs of Punta Taltal. It is built partly in the dry bed of a broad river-valley, and partly along a gently-inclined plain that fringes the bays of the coastal ranges far to the northward, running up the broader valleys to a considerable height and distance from the coast. "Wherever sections reveal the structure of this plain, it is seen to consist of sand and well-rounded gravel, derived from the harder varieties of the felsitic, porphyritic, and dioritic rocks of the adjacent hills, but containing also, near the mouths of former rivers, a lesser proportion of material derived from farther inland ; and it is mingled with recent shells, sometimes sufficiently numerous to form distinct beds. Isolated well-rounded boulders of great size are common, more especially where the mountains approach the 1 ' G-eological Observations ' 2nd ed. (1876) chap, is, p. 265. 2 'Voyage dans l'Amerique Meridionale : Geologie ' 1842, chap, vii, p. 95. 3 ' On the Geology of Bolivia & Southern Peru ' Quart. Journ. Geol. Soc. vol. xvii (1861) p. 9. Vol. 63. .] KAISED BEACHES OF TALTAL. 65 sea ; iii some places these boulders occur in well-defined lines of ancient beach. At the present sea-level, boulder-beaches are common, and form a striking feature of the coast-scenery. The width of this plain, and the altitude of its junction with the foot-hills of the mountains, varies considerably ; behind the town of Taltal it reaches to about 200 feet above sea-level. The strata dip at a gentle angle towards the sea. The surface is thinly covered with angular fragments of talus from the hills, while here and there the subjacent massive rocks break through in curiously- weathered remnants of former stacks and islets. Beyond a few stunted cacti and desert-shrubs, the plain bears no vegetation, for the formation is impregnated with saline substances. This inclined plain does not rise from the sea to the hills without interruption. Evidences of alternating upheaval and quiescence remain in lines and patches of shells, obliterated in many places and becoming more obscure as the higher levels are reached ; sufficient remains, however, to enable me to make out clearly three successive terraces, and two other more obscurely, all of them containing, so far as I am competent to judge, molluscan and other remains, in every respect resembling those of the present sea. Measured along the same line of section, the edges or cliffs of the main shell-beds are situated respectively at 15, 80, and 200 feet above sea-level; I do not state these altitudes as more than approxi- mations, since denudation has rendered their outlines very obscure. The 'island' rock-masses contain in their hollows, and protected under the talus of their summits, ' outliers' of the earlier terraces, the main development of which is observed farther inland. In many places where no shell-beds now remain, further evidence of former marine action is seen in a shelf of varying width cut along the rocky coast, and also in a line of shallow caverns. A few miles to the north of Taltal, at a place called Paso Malo, there are two picturesque caverns of considerable size, excavated in igneous rock : the mouth of one is now high above sea-level ; into the other the waves rush at high tides over gigantic boulders, the haunt of seals and sea-otters. At greater elevations than 200 feet the accumulations of shelly matter tend to become more and more obscure ; for, although calcareous masses occur at considerably-greater heights, I could find no indication of their suspected organic origin, and these may well be the surface-deposits of former springs. Shells of very ancient appearance are scattered at all elevations and far inland, but these are almost certainly due to the habits of the former Chango inhabitants and to shore-feeding birds. The quantity of molluscs and echini eaten by the lower-class Chilians of the present day is astonishing, and this must have been the case to a much greater extent when such material formed the chief article of food. The mysterious activity of the vanished natives is some- times rather puzzling in its results. Thus, on oue occasion at Taltal, I found a large and weathered block of comminuted shells at the very summit of a hill 800 feet high. Q. J. G. S. No. 249. p 6(j ME. 0. H. EVANS ON THE [Feb. I907, When examined more closely, the Taltal shell-beds present some interesting features. I will take those of Punta Taltal as an illustration. Punta Taltal was formerly an island of igneous rock, separated from the mainland by a strait some hundreds of feet wide. The gap is now bridged over by a raised beach, consisting of entire and broken shells, covered with a layer of big rounded boulders, the whole indurated by a calcareous cement derived from the decom- position of the shells. Bones of the whale are by no means uncommon in this deposit. Throughout the bed, the different genera of molluscs are curiously localized • thus, one part consists mainly of Pecten, another of Oliva and Turritetta, while elsewhere Concholepas or Pectunculus may predominate. An important feature is, that many of the lamellibranchs have their valves united as in life. The commonest shell in the modern and ancient beaches is the Concholepas. Certain shells, more particularly the Olivce, have their substance entirely converted into crystalline calcite exhibiting its characteristic cleavage. A curious change has taken place in portions of the lower beds, where they are exposed to the action of spray from the heavy breakers. Here, in many instances, the shell itself has been removed, and replaced by a delicate internal cast, so sharply taken that the faintest markings of the vanished valve are perpetuated, even to the delicate impressions of the polyzoa that formerly grew within it. In the case of the Turrittllce the effect is reminiscent of the Portland ' screw-stones/ It is very noteworthy that some of the fossils are actually replaced by internal casts of saline matter, with which, as I have said, the formation is impregnated. These curious pseudomorphs are rather scarce, and, being quite soluble in water and very fragile, seem to have owed their preservation to the shelter afforded by big boulders from percolating rain-water. Lower down in the same section there was much gypsum, and here the mass becomes very hard. Most of the shells are bleached quite white, but even in the older beaches at a high elevation, shells resembling Ghlorostoma retain their colour. The upper layer of rounded boulders gives rise to strange forms where subjected to marine erosion. Along the cliff, for a consider- able distance, the boulder- bed overhangs the sea in an inclined ledge; and, where portions of the raised beach are isolated, they assume a mushroom shape, a broad cap of the conglomerate being left supported by a comparatively-slender pillar of indurated shelly matter. In his * Geological Observations on the Coast of South America ' Darwin1 described a rock in the calcareous beds of Coquimbo, locally known as ' losa,' as consisting of minute hollow capsules, showing evidence of having been formed round fragments of shell. This feature is well exhibited in some of the Taltal raised beaches, where the material is locally made use of, to a small extent, to form 1 2nd ed. (1876) chap, ix, p. 248 ; also chap, vii, p. 162. Vol. 63.'] RAISED BEACHES OF TALTAL. 67 rough but effective filters, blocks of the ' losa ' being cut into the shape of hollow cones. I do not know that any explanation of this structure has yet been advanced, but I hazard the suggestion that it involves the solvent action of percolating rain-water upon aragonite-shell, and the subsequent deposition of the carbonate of lime in the form of the more stable calcite. Another feature due to the recent elevation of the coast relative to the present sea-level may be mentioned. The massive rocks of the coastal region are traversed by innumerable steep-walled * quebradas' or ravines, formerly carrying torrents but now almost wholly dry. Prom what I could learn from old residents, it is only at rare intervals that sufficient rain falls to permit of the temporary formation of streamlets reaching the sea ; and, generally, it may be said that erosive action due to atmospheric water is almost at a standstill in this part of the coast. The existence of these profound ravines may be brought forward as a strong argument in favour of a more humid climate in the Atacama Desert at a former period than now. The feature to which I refer, is the manner in which the beds of most of the minor quebradas suddenly alter in inclination and become precipitous as they approach the sea. Were streams suddenly to start running in these old gorges, they would terminate in water- falls. In the larger and more open quebradas, of which the beds are less inclined, this feature, if it exists, is hidden under the accumulations of gravel previously described as the coastal plain. Where the small and steep ' quebradas ' debouch upon the plain, they cut through the terraces and plain of the superficial formation and lay bare the rock-floor. If we take into consideration the com- parative inactivity of the erosive agencies, this fact would appear to indicate that the shell-terraces thus cut through are of considerable antiquity. They certainly all existed prior to the Spanish occupation, since they are covered with the graves, implements, pottery, and * kitchen-middens ' of the now extinct Changos, who never, as a people, got beyond the Stone-age culture. There are no graves below the 15-foot terrace. On the other hand, arrow-heads and flakes of chalcedony, sometimes actually rounded and rolled, are numerous immediately above the present beach and almost within reach of exceptionally -heavy surf ; but whether or no they have travelled down from the upper level, it would be difficult to decide. It may, perhaps, not be out of place to mention in conclusion that certain beds found at great altitudes, as at Talcahuano, which have been cited as proofs of a recent elevation to this extent, can, I think, be shown to be accumulations of human origin. In two such instances I found pottery and stone-implements mingled with the shells, in such a manner as to suggest that the latter formed part of extensive 4 kitchen-middens.' Having thus learned caution, I think that some of these recent shell-beds at an elevation of 1000 feet and upwards might repay re-examination. 68 the eaised beaches of taltal. [feb. i907, Discussion. Dr. J. W. Evans welcomed a further contribution to our knowledge of the elevation that had taken place in recent times on the western coast of South America. The occurrence of the united valves of lamellibranchs in raised beaches testified to the suddenness of the rise, for they would have been at once severed if exposed to the powerful Pacific surf. He himself had found Balani in raised beaches, in Northern Peru, with all the plates in position. "With regard to the question of a recent period of greater rainfall in Northern Chile, he suggested that torrential rains at long in- tervals might account for the formation of the channels that the Author had described. The Afthoe, in reply, thanked the President and Fellows for their courteous reception of his paper, and the previous speaker for his remarks upon it. The erosive action due to violent storms of rain occurring at long intervals might certainly be very considerable in beds of such friable material, and this would have to be taken into account in attempting to determine the age of the raised beaches. Vol. 6$.~] TITANIFEROT7S BASALTS OF THE MEDITERRANEAN. C9 5. The Titaniferous Basalts of tlie Western Mediterranean : A Preliminary Notice. By Dr. Henry S. Washington, For.Corr.Geol.Soc. (Read November 7th, 1906.) Contents. Page I. Introduction 69 II. Petrographical Descriptions 70 III. Chemical Composition 72 IV. Classification of the Eocks 77 V. Extent of the Region 78 • I. Introduction. In the summer and autumn of 1905 the volcanic districts of Catalonia, Sardinia, Pantelleria, and Linosa were visited by me, and their rocks collected under the auspices of, and with the aid of a grant from, the Carnegie Institution of Washington. During the past year, the abundant and representative material thus brought together has been the object of microscopical and chemical study, which is still in progress. The final results of these investigations are to appear elsewhere, as separate papers dealing with the rocks of the several districts ; but some observations and conclusions of a general character appear to be sufficiently well-established, and of enough interest, to justify their publication in advance of the more detailed descriptions. It is the object of the present communication, which I have the honour of laying before the Society, to call the attention of petrologists to the existence, in the Western Mediterranean Basin, of a hitherto unrecognized petrographic province, or comagmatic region, to adopt a term used by me elsewhere, one of the most salient characters of which is the presence of salfemanes (basalts) that contain remarkably-high amounts of titanium. The data available at present are far from complete, as only a small proportion of the numerous rock-types have been analysed : the analyses so far made by me being mostly of basalts (salfemanes), with fewer of the more salic rocks. "Furthermore, there are several gaps in the comagmatic zone, at localities which I was unable to visit, and the rocks of which are still imperfectly known. So far as it goes, however, the evidence at hand indicates that the volcanic rocks of Catalonia (including the volcanoes near Olot and Gerona), the extensive basaltic sheets of Tertiary age and those of the two great volcanoes of Monte Ferru and Monte Arci, as well as the lavas of the small recent cones, in Western Sardinia, and the volcanoes of Pantelleria and Linosa (a small islet to the south-east of Pantelleria), possess certain chemical and minera- logical features in common, which point to some genetic relation- ship between them. In other words, the existence is indicated 70 DE. H. S. WASHINGTON ON THE TITANIFEEOT7S [Feb. I907, of a comagmatic region (petrographic province) extending in a rather narrow zone from Linosa on the south-east, north-west- ward through Pantelleria and Sardinia, and possibly through the volcanoes of the southern French littoral to Catalonia. The possibility of the further extension of this zone in a southerly direction, along the eastern coast of Spain, will be discussed subsequently. For the present, we must confine our attention to the most femic rocks of the region, the basalts in common parlance, for the study of which numerous specimens and thin microscopic sections, and some twenty chemical analyses, are available. Only brief petro- graphical descriptions need be given here, and elaborate discussion of the analyses is omitted. But attention may be specially called to the mineralogical similarity among the basalts, which obtains all along the line : labradorite, augite, and olivine being uniformly the predominant and essential minerals, with accessory but constant amounts of a titaniferous magnetite and apatite, and in some cases accompanied by subordinate amounts of nephelite. Hornblende and biotite are either entirely absent from the salfemanes of the region, or present in a few rare types. The concordance in chemical composition is most noticeable in the low alumina, the abundance of the iron-oxides (ferrous oxide being greatly in excess of ferric), the relatively rather high amount of soda, the uniformly- high figures for titanium-dioxide, and the almost constant presence of notable quantities of nickel. Owing to the incompleteness of the earlier analyses of the rocks of these localities which have been examined chemically, such as those of Monte Ferru by Prof. Dcelter and of Pantelleria by Dr. Fcerstner, and the total lack of analyses of the rocks of Catalonia, Linosa, and of most of the Sardinian occurrences, the petrological connection between these localities and the peculiar chemical features of their basalts have not been suspected until recently. The first, and so far the only, petrographer to note their highly-titaniferous character was Foerstner,1 who found 5-86 per cent, of titanium-dioxide in the basalt of the island of 1891 near Pantelleria, and who suggested that this constituent was probably present in similar amounts in the basalts of Pantelleria and Graham's Island (1831), as well as in those of Etna. More recently, the probability of some relation- ship between the lavas of Sardinia, Pantelleria, and (possibly) Linosa was pointed out by me,2 although the possibility of any connexion with the Spanish rocks was not thought of. II. Peteogeaphical Descriptions. The salfemanes (basalts) are, with very rare exceptions, of common types, presenting no very peculiar or specially-noteworthy features, either in the hand-specimen or under the microscope. In 1 Tscherm. Min. Petr. Mitth. vol. xii (1891) p. 520. 2 Am. Journ. Sci. ser. 4, vol. viii (1899) p. 293. Vol. 6^.~] BASALTS OF THE WESTERN MEDITERRANEAN. 71 colour (when fresh) they vary from a medium grey, as in some of the massive flows near Olot and some of the Tertiary sheets of Sardinia, to very dark grey or black, the darkest lavas being those of the most recent cones of Catalonia, Sardinia, Pantelleria, and Linosa. They vary from very compact forms to highly-vesicular ones, the smaller cones in all the districts being composed very largely of spongy scoriae. As a rule, these lavas are not highly porphyritic, some being quite aphyric megascopically, although in most of the specimens small phenocrysts of augite and olivine are present, with small tabular phenocrysts of felspar in some cases. A peculiar characteristic of certain lavas of Catalonia, Sardinia, and Linosa, is the presence of rounded nodules of olivine of a light yellowish-green colour and coarsely-granular structure. These may attain very considerable dimensions, 4 or more inches in diameter ; and near Scano, at Monte Perru, they are accompanied by smaller, but more compact, nodules of a greenish-black augite. Large plates of a bronzy biotite are found in a leucitic basalt which occurs sparingly at Monte Ferru ; but hornblende is never seen in the specimens collected, although it was found as loose crystal-fragments in tuffs on the island of Linosa. In thin section, the mode of mineral composition is seen to be quite uniform, though varying within limits. A plagioclase- felspar, usually a labradorite, is abundant, commonly with tabular development and much twinned. With it is occasionally seen some orthoclase, but the amount of this is always very small and usually quite negligible. jS"ext to the plagioclase, augite is the most abundant mineral. This is quite colourless in thin section, and occurs as stout, subhedral, prismatic phenocrysts, which are frequently fragmentary, as well as in the usual small prismatic groundmass-crystals. It seldom forms anhedral, interstitial areas between the felspar-tables, so that an ophitic texture is very rare. Olivine is rather abundant and quite constant, although in some of the types, especially those of Sardinia, it is absent or present in negligible amount ; while in other rare cases it surpasses the augite. It presents the usual features, is colourless, varies from anhedral to subhedral, or even euhedral forms, with the common planes, and in the less fresh specimens shows the well-known yellowish-brown border. These three minerals — labradorite, augite, and olivine — are the predominant and essential constituents of all the basalts ; but with them constantly occur smaller amounts of magnetite and apatite, in the usual forms of small anhedra of the former and prisms of the latter. In some cases, especially at the Catalonian volcanoes, there is a colourless base which the analysis shows must possess the general composition of nephelite, since there is insufficient silica for the formation of felspars. But nephelite, in euhedral and distinctly- recognizable crystals, is rare in the salfemanes, though it occurs in some of the Catalonian basalts, and in some of the more salic rocks in Sardinia and Pantelleria. A few of the basalts of Monte Ferru and elsewhere in Sardinia show some very small spheroidal anhedra 72 DK. H. S. WASHIXGTOX OX THE TITAXIFEROTJS [Feb. I907, of what is apparently leucite, though the only analyses yet made of these types render the identity of this mineral somewhat uncertain. Hornblende is never seen in the thin sections of any of these rocks, but phenocrysts of biotite occur in one rare type at Monte Ferru, as mentioned above. As might be expected from the chemical composition, segirite is not present in these salfemanes, nor do the augites proper appear to carry much of the segirite-molecule. It may be mentioned here that, in the more salic rocks, in which its presence might be looked for, segirite is not a common mineral, although the occurrence of the soda-hornblende, senigmatite, in some of the Pantellerian lavas is well known; but it appears to be far less abundant than is commonly supposed. Concerning the textures little need be said. They are those usual in such femic eruptive rocks, but the generally very slight megaphyric development may be noted, as well as the almost complete absence of true ophitic textures. Many of the basalts, especially the more compact ones, are noncrystalline, while others are more or less vitreous, the vesicular forms consisting largely of glass, which is either dark in colour, or dusty and opaque with very numerous, minute, black microlites. III. Chemical Cojipositiox. The chemical composition of these basalts is shown in the accom- panying table (I, pp. 74-75), which includes only a portion of those analyses that have been made by me. Those here presented are regarded as representative of the majority of the salfemanes (basalts) of the several districts, and most of the other available examples much resemble them in their essential features. The methods of analysis were those commonly employed in the United States.1 The alkalies were determined by the Lawrence- Smith method, and titanium-dioxide by the colorimetric method of Weller. The latter, it may be remarked, is far more accurate, as well as more expeditious, than the gravimetric method so often employed ; and, as the figures for titanium-dioxide are in all cases the means of three closely-agreeing determinations, they may be relied upon. Combined water (H20 + ) was determined directly by Penfield's method, since the loss on ignition gives rise to very misleading figures, owing to the oxidation of the large amounts Gf ferrous oxide present in these rocks. Some of the analyses here presented are not complete, although sufficiently so for the object immediately in view, and are to be amplified in the future by determinations of some minor constituents, such as zirconia, nickel- monoxide, manganous oxide, cuprous oxide, and baryta. In their present form, therefore, they are to be regarded as provisional, although the corrections involved by such determinations in the figures given here will be presumably of small magnitude. It may 1 W. F. Hillebrand, * Some Principles & Methods of Eock- Analysis ' Bull. U.S. Geol. Surv. Ko. 176 (1900) ; and H. S. Washington, ' Manual of the Chemical Analysis of Rocks ' New York & London, 1904. Vol. 6$^] BASALTS OF THE WESTERN MEDITERRANEAN. 73 be remarked, however, that the low summations of some of the analyses are undoubtedly due to these non-determinations, especially of nickel-monoxide and manganous oxide. Of these analyses, the first four are representative of the Cata- lonian basalts, No. 1 of the volcanoes near Gerona, 2 of the more felspathic camptonose (felspar-basalt) - flows, 3 of the abundant limburgose (nephelite-basalt)-flows, which filled the valleys near Olot, and 4 of the scoriaceous lavas of the numerous small, recent cones. The next four include representative Sardinian basalts : No. 5 of some of the extensive Tertiary sheets, 6 & 7 of the basaltic mantles of Monte Ferru and Monte Arci respectively, and 8 of the small recent cones, the last manifestations of volcanic activity in the island. The next two are of typical basalts of Pantelleria, followed by analyses of the highly-scoriaceous lavas of the most recent submarine eruptions in the neighbourhood of Pantelleria.1 The next two analyses (13 & 14) are of the, as yet undescribed, basalts of the island of Linosa : the former being a representative of the solid lava-blocks found in the earlier phase of tuff-volcanoes, and the latter of the more recent lava- and scoria-cones. Finally 15, 16, & 17 are the early analyses by Dr. H. Eosrstner, which are tabulated for comparison with Nos. 9, 11, & 12. As regards the main constituents, these rocks present the fol- lowing characters. Silica varies considerably, the highest figures being found in the lavas of Sardinia, while in some of those of Catalonia and Pantelleria they are rather low. Alumina is rather low as a rule, and this constituent follows silica very closely, the two rising and falling together. The oxides of iron, taken together, are uniformly high, the totals varying from 10 to 13 per cent., except in the Sardinian rocks, where somewhat lower figures are met with. In every case ferrous oxide surpasses ferric oxide, the amount of the former being frequently very great as compared with that of the latter, as in Nos. 10, 12, & 14. Magnesia and lime are not very high for basalts, the former varying considerably, while the amounts of the latter are more constant, the lowest figures for both being found in the Sardinian rocks. The alkalies, while not very high, are sufficiently so in those rocks lowest in silica to give rise to normative, as well as modal, nephelite, while the soda is uni- formly dominant over the potash. Of the minor constituents, titanium-dioxide is the most notable. This constituent is present in every case in very large amounts : large, that is, for this substance, the average amount of which in igneous rocks is 1 per cent, or less. Indeed, the higher figures found in the table are unparalleled elsewhere, except in titaniferous ores, as was mentioned above. It is lowest in the Sardinian basalts, somewhat higher in those of Linosa, still higher in the Catalonian rocks, and reaches its maxima in those of Pantelleria 1 The specimen represented by No. 11 was very kindly given to ine by Prof. E. S. Dana, while that represented by No. 12 was bought some years ago of Mr. Butler, of Brompton Road, London, S.W. 74 DR. H. S. WASHINGTON ON THE TITANLFER0T7S [Feb. I907, Table I. — Analyses oe Western 6 Si0o . 44-55 4766 44-29 44-82 49-00 52-40 52-79 52-67 A1203 . 12-48 14-36 12-62 14-06 15-63 15-26 16-45 15-35 Fe20, ..... 2-81 2-83 3-61 4-56 4-03 0-74 2-74 3-82 FeO 8-54 8-44 8-84 7-27 5-00 8-33 6-44 5-42 MgO . 10-85 8-19 10-06 8-60 7-86 7*45 5-56 4-40 CaO 7-99 9-36 9-23 9-56 8'16 7-33 6-51 591 Na20 4-04 351 325 3-69 3-93 3-54 3-64 4-50 K20 2-57 1-54 1-82 2-30 2-60 0-99 1-21 2-68 H20+ .. 0-56 0-17 0-21 0-30 0-13 0-29 1-02 0-37 H20- .. 0-18 0-20 0-09 005 0-18 0-06 0-21 014 TiO> 4-32 3-83 4-92 4-25 3-25 3-12 2-64 4-04 PA 0-70 0-45 0-57 0-67 0-63 0-49 0-39 0-75 so3 0-05 n.d. 005 n.d. n.d. n.d. n.d. n.d. NiO n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0-06 0-08 0-18 0-06 n.d. MnO n.d. BaO n.d. n.d. 0-06 n.d. n.d. n.d. n.d. n.d. Totals •64 100-54 99-68 100-13 100-40 100'14 •84 100-05 1. Monchiquose ; Llord, near Gerona (Catalonia). 2. Camptonose ; Castelfullit, near Olot (Catalonia). 3. Limburgose; Las Planas, near Olot (Catalonia). Includes 0^02 Zr02 and 0-04 SrO. 4. Limburgose ; Monte Sacopa, near Olot (Catalonia). 5. Andose-camptonose ; Tres Nuraghes (Sardinia). 6. Camptonose; Cuglieri, Monte Ferru (Sardinia). 7. Andose ; Uras, Monte Arci (Sardinia). 8. Akerose; Monte San Mateo, Ploaghe (Sardinia). 9. Camptonose ; Monte Sant' Elmo (Pantelleria). 10. Camptonose; dyke in tuff, Costa Zaneti (Pantelleria). Table II. — Norms of Western 1 9 3 4 5 6 1557 10-22 10-84 12-92 19-17 17-19 4-18 8-21 1-68 8-90 24-63 19-18 2-56 19-59 12-88 4-18 7-30 1-00 1112 15-20 14-18 6-82 22-02 14-10 5-34 9-42 1-34 13-34 13-86 16-12 9-51 21-03 9-98 6-73 8-06 1-68 15'57 25-15 17-24 4-26 15-37 9-09 5-80 623 1-34 0-54 6-12 29-87 22-80 7-88 24-15 1-16 5'93 1-34 Orthoclase Albite Nephelite Hypersthene Olivine Magnetite Ilmenite Apatite ... III. 6.2.4 III. 5.3.4 III. 6.3.4 III. 6.3.4 II-III. 5.3.4 III. 5.3.4 Vol. 6^.~] BASALTS OF THE WESTERN MEDITERRANEAN. ii> Mediterranean Basalts. 9 10 11 12 13 14 15 16 17 46-22 45-72 48-97 44-83 46-55 48-84 49-87 49-24 44-64 12-23 1245 16-37 11-73 14-55 14-62 14-80 19-06 12-74 4-91 1-57 1-33 1-35 3-17 2-08 8-25 1-77 4-21 7-71 12-01 8-56 11-79 7-88 9-00 6-88 10-33 11-17 6-74 5-29 6-22 5-50 8-61 7-15 6-77 5-00 5-82 9-86 9'58 7-49 9-63 8-75 9-33 9-36 8-75 10-12 3-39 3-40 4-09 3-34 3-71 2-86 2-81 3-89 4-31 113 1-08 1-72 1-40 1-62 0-89 0-68 1-19 1-41 0-17 0-05 0-40 o-oi 0-38 0-08 0-81 o-io 0-14 0-03 0*49 7 0-07) 0-45 0-63 0-51 5-68 6-43 3-95 6-88 3-84 357 n.d. n.d. 5-86 1-46 1-54 1-04 2-14 0-55 0-36 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 005 n.d. n.d. n.d. n.d. 0-15 0-08 n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0-16 0-06 n.d. n.d. n.d. n.d. n.d. 0-20 n.d. n.d. n.d. n.d. n.d. none. n.d. n.d. n.d. 9955 99-79 100-34 99-50 99-40 99-31 99-87 99-86 100-99 11. Andose; Graham's Island (1831), near Pantelleria. 12. Carnptonose ; Island of 1891, near Pantelleria. 13. Carnptonose; block in tuff, II Fosso (Linosa). 14. Carnptonose ; Monte Pozzolana (Linosa). 15. Basalt ; San Marco (Pantelleria). Analysis by H. Fcerstner, Tscherm. Min. Petr. Mitth. n. s. vol. v (1883) p. 393. 16. Basalt ; Graham's Island, near Pantelleria. Analysis by H. Fcerstner, ibid. p. 391. 17. Basalt; Island of 1891, near Pantelleria. Analysis by H. Fcerstner, op. cit. vol. xii (1891) p. 512. Mediterranean Basalts. 7 8 9 10 11 12 13 14 4-50 1-20 7-23 16-12 6-67 6-12 10-01 8-34 945 5-56 30-92 38-25 28-82 28-82 34-58 28-30 23-32 23-58 24-74 13-34 14-73 15-57 21-13 12-79 18-35 4-40 24-46 3-80 8-64 19-54 18*67 7-91 17-22 17-05 15-46 17-22 7-00 8-06 5-91 5-21 17-88 0-28 6-08 14-44 6-78 1353 0-93 3*92 5-57 7-19 2-32 1-86 2-09 4-64 3*02 5-02 7-75 10-79 12-16 7-45 13-07 7-30 6-84 1-00 1-68 3-36 3-36 2-35 5-04 1-34 1-00 II. 5.3.4 II. 5.2.4 III. 5.3.4 III. 5.3.4 II. 5.3.4 III. 5.3.4'lII. 5.3.4 1 III. 5.3.4 76 DB. H. S. WASHINGTON ON THE TITANIFEKOUS [Feb. I907, and the neighbouring submarine eruptions. It may be mentioned, in this connexion, that two pantellerites of Pantelleria, with 69*79 and 66*07 per cent, of silica, yielded respectively 0*89 and 0-92 of titanium-dioxide, which are unusually-high figures for such quaric (acid) rocks. In a general way, titanium seems to follow the iron, and runs inversely with the silica. Phosphoric pentoxide is distinctly abundant and, like titanium, seems to follow the iron-oxides, the highest figures being found in the rocks of Pantelleria and the neighbourhood. Chlorine (derived from sea-water) is present in some of the Linosa rocks, but has not yet been determined, whence is due in part the low summation of No. 14. Nickel seems to be almost constantly present, even in the Sardinian lavas, often in considerable amounts for this constituent; and its presence is to be regarded as one of the characteristic, though minor, chemical features of the region. Although only occasionally determined as yet, its presence was established, as in the Catalonian and Linosa basalts, by the faint greenish tinge of the filtrate from the ammonia - precipitate, the amounts being approximately those of the quantitatively -determined occurrences, judging from the depth of colour. The small amounts of manganese usually found do not call for remark. It is probable that copper, the presence of which was sometimes indicated, exists only as traces, although this is a point which is to be the object of future study. Zirconium, barium, strontium, and sulphur, when looked for, were found to be absent, or present in scarcely more than traces. Coming back to the abundance of titanium, the question naturally arises as to what mineral or minerals carry it. It is clearly not present in the felspars, and neither titanite nor ilmenite could be detected in any of the thin sections. While the matter is still under investigation, the available data indicate that a large proportion of it is present in titaniferous magnetite, with probably somewhat less in the augite, and little (if any) in the olivine. No separations have yet been made of the rock-minerals, but an analysis of a dark-green augite-nodule from a leucitic lava of Scano (Monte Ferru) gave 1*91 per cent, of titanium-dioxide, while an olivine from the same locality contained only 0-10 per cent.1 As the augites of these rocks are almost, if not quite, colourless in thin section, their richness in titanium may be doubted, as it is commonly supposed that highly-titaniferous augites show a brownish-violet colour.2 It has, however, been shown recently that the green augites of Central Montana,3 and the pale-green or colourless augites of Central Italy,4 are markedly titaniferous, one of the latter carrying 2*85 per cent, of titanium-dioxide. 1 A black hornblende, found as loose crystals on Linosa, yielded as much as 8-47 per cent, of titanium-dioxide, the highest figure yet recorded for this mineral. 2 F. Zirkel, 'Lehrbuch der Petrographie ' vol. i (1893-94) p. 284; and H. Rosenbusch, ' Mikroskopische Physiographie der Massigen Gresteine ' 4th ed. vol. i (1905) 2nd half, p. 208. 3 L. V. Pirsson, Am. Journ. Sci. ser. 4, vol. xx (1905) p. 39. * H. S. "Washington, ' The Roman Comagmatic Region ' Carnegie Inst. Publ. No. 58 (1906) p. 334. Vol. 63.~] BASALTS OF THE WESTERX MEDITERRANEAN. 77 IV. Classification of the Hocks. The classification of these lavas according to the prevailing systems has been sufficiently indicated in the foregoing pages. For the most part, they are felspar-basalts, with fewer nephelite-basalts, these last occurring especially in Catalonia and not having been, as yet, definitely determined from the other districts. These basalts are usually olivine-bearing, although in Sardinia olivine-free types are rather common. The classification according to the quantitative system is based on the figures furnished by the analyses, and on the calculated norms, which latter are shown in the appended Table II (pp. 74-75). In this the norms are numbered as in Table I of Analyses, and the symbols representing the class, order, rang, and subrang are given in each case below. The great majority of the basalts lie within the salfemane class, the exceptions being some of the Sardinian basalts and that of Graham's Island, which are in dosalane, these being distinctly higher in normative felspar, especially albite and anorthite, than the others. Outside of Catalonia, where normative (and modal) nephelite is so abundant as to cause some of the types to fall in the sixth order, with felspars dominant over nephelite, the order is uniformly the fifth ; that is, the quantities of either quartz or nephelite are negli- gible as compared with the felspars. The rang is almost as uniformly the third, with alkalies and salic lime in about equal amounts, and in only two cases are the alkalies dominant over salic lime (Nos. 1 & 8).. The relation of the alkalies is very constant, soda being dominant over potash in every case, so that the subrang is invariably the fourth. Although, in the salfemanes, the femic x constituents form about one half of the rock, their relations, as expressed in the minor divisions of grads and subgrads, may be disregarded in the present brief discussion, as unnecessarily prolonging it, and introducing what may seem to be a superfluous refinement into the present introductory and little tried stage of the new classification. As illustrative of the correlation of the two systems of classifica- tion, a few points may be dwelt on very briefly. While all those rocks, which are free from nephelite, would be called basalts in the prevailing systems, it will be observed that the distinctions be- tween them are more numerous according to the quantitative system. The basalts of Pantelleria and of Linosa are uniformly in camptonose (in salfemane), as are also many of those of Catalonia. On the other hand, many of those of Sardinia fall in andose or akerose in 1 It is to be remembered that the term ' femic ' applies only to the standard, non-aluminous minerals, like ideal diopside, hypersthene, olivine, or magnetite. Such ' ferromagnesian ' minerals as augile, hornblende, or biotite, which contain alumina, are termed ' alferric,' and their molecules are resolved into salic and femic components in the calculation of the norm. It may thus happen that a rock with augite very much more abundant than plagioclase (and hence at first glance apparently dofemic) is actually in the salfemane class. 78 DE. H. S. WASHINGTON ON THE TITANIFEEOT/S [Feb. I907, the dosalane class, thus clearly indicating by their systematic names their great content in silica and alumina, and their lesser content in the femic constituents, such as iron-oxides, magnesia, and titanium- dioxide.1 These Sardinian basalts, furthermore, are almost the only basalts that ^show in the norm high hypersthene (which enters into modal augite), and little or no olivine, and the comparative rarity of this last mineral among them has been noted above. Again, the basalts of Catalonia, which are almost the only basalts with recognizable nephelite under the microscope, are similarly the only ones to fall in order 6, with notable amounts of this mineral in the norm. Finally, it was pointed out on a previous page that in this series lime is not very high, that is, for such basaltic rocks ; and this feature is revealed in the magmatic position of these types in alkalicalcic rangs, or even in domalkalic ones : whereas, as has been pointed out elsewhere,2 the majority of ' basalts ' fall in docalcic rangs, such as hessase or auvergnase. It should be borne in mind that the new names used here express only the magmatic (chemical) characters of the rocks. The mineral and textural features are to be expressed according to the proposed system by qualifying compound adjectives, or eventually by typal adjectives. But further discussion of these and cognate topics is uncalled for here. Y. Extent of the Region. The real extent of this zone or region of chemically and mineralo- gically similar rocks is as yet problematical, and its full discussion must be reserved for the future. The possible richness of the Etna basalts in titanium, and their connexion with those of Pantelleria, has been suggested by Dr. Fcerstner in au article cited above. But no complete and trustworthy analyses of these lavas are available, those of Sartorius von Waltershausen, Jewett, Silvestri, and Bicciardi being manifestly at fault as regards either accuracy or completeness, or both combined. In their figures for silica, the oxides of iron, lime, and the alkalies, the Etna lavas are much like the Pantellerian basalts ; and the high figures for alumina commonly reported maybe due, in part to admixture with magnesia (which is commonly low), and in part to the non-separation of titanium-dioxide, which would be precipitated and weighed with it. Along the southern coast of France are several ' basaltic ' volcanoes, as at Montpellier and Agde, and it is possible that these may eventually turn out to be connecting links between those of Sardinia and Catalonia, but their chemical characters are quite unknown to me. A volcanic zone, in "which ' basalts ' occur, extends south from Catalonia along the eastern coast of Spain, including the Columbretes 1 Exceptions to this rule are apparently presented by Nos. 5 & 6, but No. 5 (with less silica than the others) is near the dosalic border of salfemane, while in No. 6 the higher magnesia and lime (as compared with those of Nos. 7 & 8) serve to throw the rock into the salfemane class (camptonose), despite its high silica. 2 H. S. Washington, U.S. Geol. Surv. Prof. Paper No. 14 (1903) p. 75. Yol. 6$.^ BASALTS OF THE WESTERN MEDITERRANEAN. 79 Islands, the neighbourhood of Cartagena, Cabo de Gata, and Alboran Island. But their rocks demand further chemical investigation, the earlier analyses either neglecting the titanium or giving rise to uneasiness on the score of accuracy. In a recent highly-interesting paper x Dr. A. Osann has described the rocks of two localities in Murcia, and his description is accompanied by careful and complete analyses by Dittrich. These do not show the high amounts of titanium which we might expect if the rocks belong to the same region as that dealt with here, although they are somewhat higher than the average in this constituent. A possible extension southward from Linosa is indicated by the occurrence of a phonolite at Msid Gharian, near Tripoli, described by Prof. L. van Werveke.2 The possible connexion of the rocks of Pantelleria with those of Abyssinia and the Great Eift Yalley in East Africa, has already been suggested by Dr. G. T. Prior.3 Discussion. The President expressed the gratification with which the Society received this paper, as a recognition from the Author of his election as one of the Society's Corresponding Fellows. The paper was an extension of the work which, for some j'ears past, the Author had been carrying on in the basin of the Mediterranean. It showed the same firm grasp of petrographical methods, the same reliance on minute and accurate chemical analysis, and the same successful €o-ordination of facts in the natural history of rock-groups. The high percentage of titanium in the rocks now described was a point of considerable interest and importance, and seemed to justify the Author's separation of the region of the Western Mediterranean as a distinct petrographical province, so far at least as regards its later basaltic eruptions. Dr. Teall agreed with the President in his estimate of the value of the paper, which dealt with a very interesting and somewhat peculiar group of rocks. The Author had done much to give definiteness and precision to our chemical knowledge of igneous rocks, and he (the speaker) felt sure that all the Fellows would welcome this communication. Dr. J. W. Evans thought that the paper emphasized the import- ance of exact and complete analytical work, especially in connexion with the minor chemical constituents. He had had the oppor- tunity of examining numerous concentrates of the heavy minerals of sands, and was struck by the prominent place taken by ilmenite and other titanium-bearing minerals. He also drew attention to the large percentage of titanium-oxide which is often present in bauxite, usually a product of the decomposition of igneous rocks; and expressed his belief that many other occurrences of rocks rich in titanium would be discovered. 1 'Ueber einige Alkaligesteine aus Spanien' Rosenbusch Festschrift, 1906, p. 263. 2 L. van Werveke, Neues Jahrb. vol. ii (1880) p. 275. 3 Min. Mag. vol. xiii (1903) p. 228. 80 ME. W. E. BALDWIN-WISEMAN ON [Feb. 1907, 6. The Influence of Peessebe and Poeosity on the Motion of Seb-Sebface Watee. By William Ralph Baldwin- Wiseman, M.Sc, ABSocM.Inst.CE., F.G.S. (Bead June 27th, 1906.) [Plate V— Map.] Contexts. Page I. Historical Introduction 80 II. Experimental Data on Porosity and the Flow of Interstitial Water 81 III. Experimental Data on Variation of Pressure in the Interstices of a Bock 94 IV. Field-Observations 97 V. Bibliography 103 I. HlSTOEICAL INTBODECTION. Since the early part of the last century the question of the behaviour of underground water has received the attention of numerous investigators, whose labours have resulted in the compilation of a most voluminous and scattered bibliography, comprising records of field-observations, experimental data, and mathematical deduc- tions, many of which are difficult of access. I have therefore, although deeply conscious of the omission of the names of many worthy investigators, endeavoured to summarize briefly the more important investigations on this subject, with the view rather of outlining the work, than of giving a full record of workers. In 1837, Robert Stephenson (l)1 first noted the formation of a cone of depletion in the water-logged sands of the Inferior Oolite, during the progress of the construction of the Kilsby Tunnel on the London & North- Western Railway ; and in a later report to the London & Westminster Water Company, he remarked upon the high absorptivity of the Chalk and the intermittent nature of its surface- streams. The first systematic well-measurements were made by Bland (2) in 1831, along two parallel lines from Sittingbourne to Maidstone ; and ten years later Clutterbuck prepared a somewhat similar section on a line from Dunstable to Watford. In 1851 Ansted (3) experimentally determined the rate of percolation of water through Chalk, under comparatively-low pressures ; and seventeen years later, in 1868, Isaac Roberts (4) published a few figures showing the effect of pressure on the rate of flow of water through the Red Sandstone of the Liverpool district. In 1856 Darcy (5) stated that the rate of percolation of water through sand varied directly as the pressure, or head, on the water, but inversely as the thickness of the bed traversed. Hagen (6) questioned the first part of this proposition, while agreeing as to 1 Numerals in parentheses after authors' names, throughout this paper, refer to the Bibliography, § V, p. 103. Vol. 6^.~] THE MOTION OF SUB-SURFACE WATER. 81 the second part ; Seelheim (7) demonstrated that the flow increased faster than the pressure ; and Hazen (8), from a study of experi- mental filter-beds, stated that the flow was affected, not only by the pressure and the thickness of the bed, but also by the relative sizes of the constituent sand-grains of which the bed was made up. Ten Brink, Theim, Pettenkoffer, Wolff (9), and others have deduced data on the rate of flow of sub-surface water, by observa- tions on the time of flow of water charged with fluorescin, common salt, and lithia, from one well to another ; and, more recently, Slichter (10) has devised an ingenious method of recording electrically- the time of passage of water charged with an electrolyte from one well to another. Seelheim, King (11), Van Hise, and Moore (12) have investigated the variation in the porosity of strata with superincumbent pressure and faulting. Ansted, Prestwich, Boyd Dawkins, and others have supplied much information on the storage-capacity of the Chalk ; and Sterry Hunt, Wheatstone & Daniell (13) have familiarized us with the porosities of a great variety of rocks. Baldwin Latham (14), Honda (15), Pantanelli (16), Weyde (17), Lucas (18), and others have noted the periodic variation in the levels of the ground-water, and its interdependence on rainfall and variations of barometric pressure. Among the more physical and mathematical contributions are Slichter's (10) mathematical analysis, giving results for the motion of water in rocks not unlike that of electricity in conductors; the researches of Osborne Reynolds (19), Cohen (20), Wollny (21), Welitsch-Konsky (22), King (11), and others, on the variation in the viscositjr of a fluid with pressure and temperature ; and of Girard (23), on the effect of dissolved salts on the rate of flow of fluids through capillaries. Finally, there have been numerous surveys, of greater or less extent, which have materially contributed to a more intimate knowledge of the geology and hydrology of particular districts ; among the best of these are the Reports of the 2nd and 3rd Royal Commissions on London Water of 1892 and 1897, and the monographs on W^ater-Supply of the Geological Surveys of Great- Britain and the United States of America. II. Experimental Data on Porosity and the Flow of Interstitial Water. I do not propose to attempt a discussion of all the many factors which have an important bearing upon the quantity and the motion of underground water, but to confine myself to the consideration of the effect of porosity, pressure, surface-configuration, and stratigraphical sequence upon the storage and motion of this water. At the outset, one experiences a difficulty in assigning an exact definition to the term porosity ; for the measure of the porosity of a rock is largely affected by the viscosity and temperature of the Q. J. G. S. No. 219. g 82 MR. W. K. BALDWIN-WISEMAN OX [Feb. 1907, percolating fluid, and the pressure to which that fluid is subjected : it is also still further complicated, as I shall show later, by variations in the physical structure of the rock and by the cushioning of the air in the innermost interstices. Thus, for instance, the porosity of marble is very small if it be determined by immersion in water under ordinary conditions of temperature and pressure, but if it be determined by immersion in oil the result is somewhat higher ; and, with water under conditions of high temperature and great pressure, much larger values would,, in all probability, be obtained than with water under normal conditions of temperature and pressure. During the course of my experiments upon flow and resoakage — recorded, with other data, in a paper published in the Minutes of Proceedings of the Institution of Civil Engineers (24) — I found that when water was forced into the rock under pressures of 40 or 60 lbs. per square inch, the water-capacity after the removal of the pressure was much higher than that for ordinary tank-soakage, or for soakage under reduced pressure, as when the soaking-basin was placed under the receiver of an air-pump. Thus, a piece of Upper Chalk from Micheldever (Hampshire) had a storage-capacity, after subjection to a pressure of 40 lbs. per square inch, of 0*4679 of its total volume, or a storage-capacity of 2-92 gallons per cubic foot. Upon re- charging, it took up a volume of water equal to 28*1 per cent, of its total porosity in the first second, which had increased to 57 '2 per cent, in 4 seconds and to 74*7 per cent, in 9 seconds : the volume of the several quantities of absorbed water varying, roughly, in the ratios 1, 2, and 3, and the time-interval in the ratios of 1, 4, and 9, or as the squares of the first ratios. But thereafter the rate of absorption continually decreased, and thus only 772 per cent, of the total storage-capacity was charged in the first half-hour ; while the rate increased still more slowly to 78 per cent, in 1 hour, 79 per cent, in 4| hours, and 83*1 per cent, in 47 hours. Under the receiver of an air-pump, the absorption during the first half-hour was somewhat greater than that under ordinary conditions of soakage, the quantity absorbed being about equal to that of 4| hours of ordinary soakage ; but thereafter the rate of absorption did not appear to be accelerated by further operation of the air- pump, nor were any observable air-bubbles given off from the stone. Similar characteristics in the rate of absorption to that of the \Ticheldever Chalk are shown for other stones in the appended Table (I, p. 83). It is interesting to note, as Prof. Boyd Dawkins pointed out in his James-Forrest Lecture before the Institution of Civil Engineers (1), that the quantity of water taken up by a rock upon recharging is somewhat less than its original water-content ; and the explanation seems to me to be that, as the water penetrates to the inner- most pores, it expels the air from the pores into which it enters, part of the air escaping externally, while the remainder passes into the innermost and finer interstices. With further additions of Vol. 63.-] THE MOTION OP SUB-SURFACE WATER. 83 percolating water, this air is cushioned and compressed, and at pressures slightly higher than the normal prevents the ingress of water to the pores that it occupies. Consequently, a recharged rock may be considered as an aggregation of water-charged pores surrounding a nucleus of air-charged pores; while, in a fully- charged rock, the water occupies uniformly all the pores. There is some confirmation of this theory, in that the rocks with coarser interstices are more readily recharged, and take up an initial quantity of water more nearly approximating to their full capacity, than do those rocks that have finer interstices. Table I, showing the Eate of Absorption of Water by various Stones : the Water absorbed being expressed as a Percentage of the Volujie of the Stone. (Continuous immersion in a beak er of water, at atmospheric pressure.) Number of hotirs im raersion. Chalk. Bath Weatherstone. Millstone Grit. Remarks. Mottisfont. Micbeldever. Piece 1. Piece 2. Piece 3. Piece 4. Piece 1. Piece 2. Piece 1. Piece 2. 34-65 36-34 11394 187-15 36-48 40-12 135-50 68-47 Weigh t,dry 0-5 ... 36-26 35-41 3977 36-13 20-29 22-55 12-34 13-30 10 ... 36-53 3581 40-23 36-49 20-70 2303 4-5 ... 36-96 3661 40-29 36 99 22-45 23 93 47-0 ... 39-51 38-16 4239 3888 2397 23-93 45-86 46-79 24-18 14-98 Maximum. On account of this cushioniug action of the air, I consider that all determinations of the flow of water through rock based upon corresponding determinations with air, and the ratios derived from the relative flow of air and water through capillary tubes, are illusory, as air will not cushion air and interfere with the flow of air through the interstices of a rock, while at moderate pressures the cushioning air will seriously interfere with the flow of the water. Therefore the two discharges will not be directly comparable, as there is not a corresponding interference in the capillary tubes ; and, farther, this interference will be of greater magnitude in a rock with many fine pores than in one with a lesser number of coarser pores — resulting in a corresponding increase in the error of the calculated discharge. The rate of drying of saturated stone will, of course, vary with the fineness of the pores, and with the temperature and velocity of the air surrounding it. When the temperature is normal and the motion of the air is only that of a closed room, the rate of desiccation is e 2 84 3JE. W. E. BALDWIN-WISEMAN ON [Feb. 1907 extremely slow ; but, when there is an increase in the velocity of the air-current, or in the temperature of the surrounding air, desiccation proceeds at a greater rate. Thus, for instance, in experiments recorded in another paper (24), the quantity of inter- stitial water evaporated in 165*9 hours when the temperature was 8° or 9° C. was only 032 of that evaporated in 5-7 hours when the temperature was 95° C. ; and, for the same degree of initial saturation, the ratio would have been much less than 0*32. Most of the water was expelled from the pores during the first few hours' exposure ; for, when stones were continuously exposed to a temperature of 98° C. in a steam-oven for a period of 6 days, there was little or no appreciable difference of weight when cooled, between the weight at the end of each consecutive 12-hour period and that at the end of the first 6-hour period. I also found that most of the moisture was expelled at this temperature ; for, upon subsequently exposing some test-pieces, which had been previously dried, for a period of 1 hour to a tempe- rature of 98° C. in the steam-oven, and thereafter for a period of 2 hours to a temperature of 300° C. in the electric furnace, I found that the decrease of weight, as shown in the following Table (II), did not affect the resultant capacity for contained water by more than 0-5 per cent. Table II, showing the Effect of Drying Stones in a Steam-Oven for 1 hour at 98° C. and in an Electric Eurnace for 2 hours at 300° C. Variety of stone. Volume in cub. cms. Weight in grammes, after drying in Difference of weight Steam- oven. 1 Electric furnace. in grammes. 0-20 o-oi 0-25 001 0-05 o-oo as a percent. \ of the ,' volume, i : York 62-8 69-4 58-4 58-3 49-2 34-9 135-73 13953 12735 127-08 98-80 61-30 135-53 139-52 127-10 127 07 98-75 61-30 0318 0014 | Red Mansfield 0-428 Portland Base-bed ... Monks Park 0-017 0102 I Bradford Oolite o-ooo 1 In all cases recorded in this paper, the porosity is calculated from the difference in weight of several specimens of the particular stone after prolonged soaking under a hydrostatic pressure of about 40 lbs. per square inch, and the respective weights of the same specimens when dried in the steam-oven until there was no further diminution of weight : the specimens not being weighed until they had cooled to about 10° C Yol. 63.] THE MOTION OF SUB-SURFACE WATER. 85 In strata of uniform texture the porosity will vary inversely with the pressure, and consequently with the depth beneath the surface, until a point is reached at which the porosity has zero value. This limit is styled by Prof. Yan Hise the base of the zone of fracture, and is fixed by him, upon more or less empirical deductions, as situate at a depth of about 6 miles below the surface. Considering more commonplace conditions, the porosity will vary with the past history of the strata and of the locality in which they occur ; and it is most essential that the geological record should be studied side by side with the flow-problem in every hydrological investigation, although, strangely enough, this procedure seems to have been the exception rather than the rule in the past, and the subject seems to have beeu approached rather as a laboratory- experiment, or a problem in hydraulics, with little or no reference to the dynamical geological aspect. Thus, for instance, one theory has been elaborated on the groundwork of experiments with sand- filters ; but I have shown mathematically and experimentally, in my other paper (24), that the porosity of sand depends almost entirely upon the fortuity of its arrangement and previous physical treatment, and it is at once evident that data obtained from experi- ments with such sand are inapplicable in the case of, say, a sandstone with inequalities of porosity in its cementing-material, and still more so when that sandstone has been , faulted and folded or subjected to infiltration. In a very interesting paper, C. C. Moore (12) has shown that, at the Caldy-Grange fault at West Kirby, the porosity of the Keuper Sandstone varies from 0*2256 of the total volume at a distance of 24 feet from the face of the fault, to 0*1650 at a distance of 3 inches from the fault ; and, on the other side of the fault, the porosity of the Bunter Sandstone varies from 0*1480 at a distance of 3 inches from the face of the fault, to 0*255 at a distance of 25 feet from the face, — or that, within a distance of only 49 feet, the porosity of the strata varies from 1*00 to 0*74 and from 0*66 to 1*13. In the course of my own observations, I have noted similar phenomena. Thus, in a flexure of folded red Peel Sandstone, exposed on the shore of a little cove north of Whitestrand Bay, near Peel, in the Isle of Man — a region which has been subjected to pressures so severe that fragments of quartzite have been forced into the main mass of slates of the district — the specimens col- lected from the crown of the flexure had a porosity, expressed in terms of the volume, of 0*161 ; while at a point of less curvature, at a distance of only a few yards from the crown, the rock had a porosity of but 0*034, or, roughly, 0*2 of that at the crown. The effect of an intrusive dyke of dark olive-green Tertiary diabase in black Carboniferous Limestone, at Pool-y-vaash Bay, Castletown (Isle of Man), is also shown in the following Table (III, p. 86). 86 ME. W. E. BALDWIN- WISEMAN ON Table III. [Feb. 1907, No. of specimen. Description of rock. Distance from dyke, in feet. Percentage volume of contamed water when soaked. 1. 2. 3. 4. 5. 6. 7. 8. Unaltered djke-rock, almost black in colour 27 30 90 6-88 4-81 13-49 12-42 13-50 308 2-29 0-24 Slightly-altered dyke-rock, between bigh and low water, dark olive- Chalky, dull-white limestone, em- bedded in dyke-rock Chalky, dull-white limestone, in contact with dyke-rock Dense black, somewhat flaky, lenti- cular limestone Dense black limestone, with little or no tendency to break into layers or prisms Do. do. do. Dense black unaltered limestone, with irregular conchoidal fracture and no tendency to break into In another case, highly-fossiliferous Carboniferous Limestone from the shore near Port St. Mary (Isle of Man), collected above high- water mark, had a porosity equivalent to *0078 of the total volume: while fragments broken from pinnacles of waterworn rock between high and low water had a porosity of *0341, — an increase of nearly 350 per cent, in a distance of only 100 yards. It is at once evident that, when the possibility of the variation of the porosity of a rock is of such a nature as any of the instances previously quoted, one could not presume an uniform rate of flow in such an area. In fact, one is not justified in assuming conditions of uniform flow in any area, without substantiating it by rigorous investigations in the field. Yet mathematical theories of flow are formulated, which are based upon the fundamental assumption of a homogeneous rock-texture: the results obtained being, as one would expect, almost identical in every respect with that of the passage of electricity through a conductor. Such a process possesses but little accuracy or reliability, and not infrequently is at utter variance with the data derived from field-studies. To arrive, therefore, at a reliable estimate of the rate of flow of water through any rock, or its storage-capacity, something more than these mere empirical assumptions is essential ; and investigations in the field must be supplemented by the data derived from laboratory-experiments, carried out with test-pieces of fair samples of the rock of the locality. Vol. G^.'j THE MOTION OF SUB-SURFACE WA.TBE. 87 ISTearly all investigators of interstitial flow have considered it as a motion through a series of capillaries of varying diameter, and of a length much greater than the net thickness of the strata traversed. Slichter (10) has assumed that rocks of varying degrees of porosity can he represented by spheres packed in different orders of com- pactness, having a maximum value of porosity ( = 0-4764) when the hounding tangent-planes to the spheres form a cube, and the least value ( = 0*2595) when the tangent-planes form a rhomboid with a dihedral angle of 60°; and, in a neat mathematical analysis, he has evaluated the diameter and length of the equivalent interstitial tube for a given thickness of rock of given porosity. In the series of experiments which I conducted upon the influence of pressure on interstitial flow, and recorded in tabular form in the appendices to my former paper (24) previously mentioned, I made no attempt at the determination of the length, or cross- sectional area, of this ideal capillary tube, as it seemed to me to be capable of almost infinite variation in these particulars, as well as in the numerical frequency of such tubes per cubic foot of rock ; but rather confined myself to a close investigation of the rate of variation of discharge with pressure: and I found that, for a wide range of pressure, the discharges were not strictly pro- portional to the pressure. Thus, in the case of hard Daresbury Sandstone, whilst the pressures varied in the ratios of 1, 2, 4, 8, and 12, the corresponding discharges varied in the ratios 1, 2*4, 6*6, 10-7, and 14-1. The variations are still more apparent if one divides the dis- charge from any test-piece by the pressure producing it, and expresses the unit-discharge or discharge per unit-pressure in terms of the volume of the pores of the test-piece, as in the appended Table (IV, p. 88). From a study of this table, one sees that the unit-discharge steadily increases throughout the whole range of pressure in the case of the Oolites ; while, in the case of the other rocks tested, the unit-discharge steadily increases until a certain pressure, which I have called the critical pressure, is reached, and then falls off with a steady decremental ratio. Thus, for instance, the hard Daresbury Sandstone, 6 inches thick, has an unit-discharge or a discharge per lb. of pressure at a pressure of 5 lbs. per square inch that is only 0*61 of that at 20 lbs. per square inch, which for this thickness of this stone is its pressure of maximum unit- discharge, the rate of increase between 5 and 20 lbs. per square inch being steady ; but thereafter the unit-discharge steadily decreases until at a pressure of 70 lbs. per square inch the unit- discharge is only 0-64 of that at a pressure of 20 lbs. per square inch. For a thinner section of the same rock this phenomenon is noticeable at a lower pressure. The maximum unit-discharge for the 3-inch thickness of hard Daresbury Sandstone occurs at a pressure of 15 lbs. per square inch, instead of at 20 lbs. per square inch, which was the maximum for the 6-inch thickness, and the sc 8§ pq a % CO^Q0t-C(M(M Ci iO t- 1» t- QC 00 00 ^ cm cm cm cm cm cm cm CO i— iQNOir- 1 I> © •* O Nt> H H CO ^ r-, C C. cp-Xr-rtTHOCQOt-iO^COr-iC. cMcb^^^^cbcbcbcbcbcbcboi (M N O T)l C. rH Oi ro ■* ■* © * (M o O CT CO iO O r- « -. CO C N Q CD CO I>Cli-iCNi-ir-(OOCiOC5CC'OOCO ■*COCX?DCCCC5CCCCi3-^l> c j> c: r> cc t^ ci ^ c c^ r- ihcd i-H CM CM CM (MCM!M(NCqOI>-*HCO 00»0»QOiQOiC;Oi-0'*^^CO 00 h C C i> Q 00 -h Ol CO H CO o c "■ Ol C5 C C (M O Ci N i-i CT. C5 CO CO CO <* C CI tO l-- CO CC' OS -H CO J> |> t- OOOOOOOOOi-it-ii-ii-h^- co ic cm cm oi n c c c: co o c ■# x CtvtCOffiNCOCCOC^OCM H rH -H rH r-l M r- Ol O'l M O: CO CO ^ oooooooooooooo ■#^C01NO"1C ooooooooo ooooocoxcooiTtHoqoccoco o o oo oo COCOCOCit^tCOC'-HCOvittCO COXOCMCOTrCtOCOO OOOl— ll- 1 — 1— i I— it— I rt (M ooooooooooo CM 1 COCT.OH>tHNI- 0000X>-CC«C«0Oic0 CO CO CO CO CO CO CO CO oooooooo CHtCXWCH rr O CO t~ 00 OS CO CO CO CM CM Ol CM CO © © o c © © o © cfu© I lO o >o o o C iO o o c c o S- S rlr-tNWCOCO't^lCLOtOCb- © 5-<-i Vol.63.] THE M0TI0X OF SUB-SURFACE WATER. 89 correspou cling ratios are 0*68 and 0*72, at pressures of 5 and 70 lbs. per square inch respectively. Similar phenomena were exhibited by the specimens of Millstone Grit, the pressures of maximum unit-discharge being 60 and 35 lbs. per square inch, for thicknesses of 6 and 3 inches respectively ; and the ratios of the unit-discharge at pressures of 5 and 70 lbs. per square inch to the respective maxima being 0*19 and 0*97, and 0*97 and 0-73. The Chalk exhibits still more irregular variations : the Mottis- font Chalk having a maximum unit-discharge at a pressure of 5 lbs. per square inch, which decreases steadily to a minimum value = O'SO of the maximum at a pressure of 20 lbs. per square inch, and then steadily increases to an unit-discharge =0'96 of the maximum at a pressure of 35 lbs. per square inch, which is the highest recorded pressure for the chalk from this locality, as a little above the pressure of 40 lbs. per square inch the stone ruptured. The Michel- dever Chalk exhibited a more variable unit-discharge, first increasing with the pressure to a maximum unit-discharge at a pressure of 10 lbs. per square inch, then decreasing at a pressure of 15 lbs. per square inch to an unit-discharge =0*98 of that at the maximum, a value only slightly less than that observed at a pressure of 5 lbs. per square inch ; thereafter the unit-discharge increases to a value = 0*99 of the maximum at a pressure of 20 lbs. per square inch, and then it steadily decreases to 0*92 of the maximum unit-discharge at a pressure of 40 lbs. per square inch, above which stress the stone ruptured. From a general consideration of the previous table, we see that there is no simple direct connexion between porosity and discharge, and we must seek for some other explanation of the extreme variability of the discharge of the several rocks. Keeping to the assumption that the flow is analogous to that through capillaries, and that the phenomena of capillary flow are comparable with those of ordinary pipe-flow, then the extreme variability of flow may be due to the greater or less sinuosity of the interstitial tube, or to the extreme variability of its cross-section from point to point, giving rise to losses of energy such as eddies, etc., which always result from unsteady fluid-motion, or to the magni- tude of the coefficients of friction of the various rocks, or to a combination of these causes. Further, as in ordinary pipe-flow, an increase of pressure up to a certain pressure will be productive of an increased flow, but when that pressure is exceeded the excess of pressure is expended only in the production of eddies and excessive friction, and the discharge per unit of pressure more or less rapidly diminishes with increase of pressure, so also these phenomena may hold for the interstitial tube. This critical pressure varies for different rocks, and for different thicknesses of the same rock. Thus, for instance, for the slowly-percolating water in the interstices of the Oolites, there was no critical pressure within the range of the pressures in the experiments, but in the more numerous and finer capillaries of the Chalk the flow was relatively faster, 90 MB. W. B. BALDWIN- WISEMAN ON [Feb. 1907. and the critical pressure was manifested at the low pressures of 5 and 10 lbs. per square inch for the Mottisfont and Micheldever Chalk. In the coarser interstices of the Millstone Grit the flow was comparatively slow, and the critical pressure was not attained until the relatively-high pressures of 60 and 35 lbs. per square inch were reached, for the 6-inch and 3-inch thicknesses of stone respectively ; while, in the coarse interstices of the Daresbury Sandstone, the flow was very rapid compared with that in the other rocks under similar pressures, and the critical pressure was in evidence at the com- paratively low pressures of 20 and 15 lbs. per square inch for the 6-inch and 3-inch thicknesses respectively. With these ex- periments in mind, it is therefore not surprising that different investigators have formulated somewhat conflicting statements — based upon experimental data, derived generally from pumping experiments which they have conducted — to the effect that the flow varied directly with, or faster than, or more slowly than, the pressure : the deductions being entirely dependent on the relation of the range of pressure considered, to the critical pressure for flow in that particular rock. It is, of course, highly probable that differences of pressure as great as those in my series of experiments are far in excess of the differences pertaining to normal natural sub-surface flow, but they serve to afford data in pumping investigations, as I have proved in the paper (24) to which I have previously referred. Thus, in a well, the inflow at the apex of the cone of depletion is accelerated by the removal of the column of water between the rest-level and the reduced working-level of the water when pumping, the pressure being reduced by an amount proportional to this height ; and this is not inconsiderable, as the following Table ( V) shows : — Table Y. District. Pumping, station. Geological formation. Difference between rest-level and work- ing-level, in feet. When pumping, gallons per hour. Equivalent pres- sure in lbs. per square inch. 2-31 feet of water = presstcre of lib. per sq. inch. Barnoldswick... Birmingham . . . Hinckley St. Helen's Eyde Whitemoor. Perry Sink- ing. Snarestone. Kirkby. Knighton. Ashey. Itchell Crondall. Millstone Grit. Triassic sand- stone. Do. do. Do. (Bunter). Lower Green- sand. Upper Chalk. Do. do. 78 180 80 90 40 50 48 . 15,000 25,000 7,500 62,500 16,700 8,300 8,300 33-8 77*9 34-6 39-0 173 21-7 20-8 Do Farnborough... Vol. 63.] THE 3H0TI0X OF SUB-SURFACE WATER. 91 The now at all other points within the periphery of the cone of depletion is also increased by an amount proportional to the corresponding differences of level. At points on the margin of the basal area of the cone of depletion, the difference of level (as also the increase of velocity) is zero, or the velocity at such points is that of the normal interstitial flow. It is not often that an opportunity offers to collect any exact in- formation on the effect of great differences of natural pressure on the sub-surface flow, although, if such data were collected, they would be of considerable interest. Prof. Boyd Dawkins, however, informed me, some time ago, of an instance recorded in the course of the Xorthwich Brine -pumping Subsidence Compensation Enquiry : during Christmas 1892, there was a 20-foot subsidence in a field at Marston, probably due to the abstraction of the underlying salt, by the flowing brine on its way to the pumps, and the caving-in of the superincumbent rock ; almost simultaneously with the subsidence a rise of the water-level occurred in the pump-wells at Messrs. Brunner, Mond & Co/s Works at North wich, over 2 miles away from the subsidence. In all probability the caving-in of the strata set up a wave of compression which passed rapidly through the sur- rounding rock, causing an instantaneous increase of velocity in the interstitial water, and an increased delivery into the wells. Another interesting record is that of Messrs. S. Cortauld & Co/s well at Booking (Essex), recorded in several issues of the British , Association Reports. The water-level was only 12 inches above the surface (130*7 feet O.D.), on April 21st, 1884, the day before a severe earthquake ; but the next record, on April 28th, gives the level as 31*5 inches above the surface. This increase continued until July 7th, when the maximum level of 58*5 inches above the surface was attained. Other water-levels of this well are shown in the following Table (VI) :— Table VI Year. Hei Maximum. r/ht of vjater ah Bate. ove surface, Minimum. in inches. Bate. Maximum annual difference of level, in inches. 1883... 19 March 26th. 8 October 8th. 11 1884... 58-5 July 7th. 9-5 January 14th. 49 1885... 46 April 7th. 29 December 14th. 17 1886... 37*5 January 18th. 265 July otb. 11 If sufficient data of similar nature to those already discussed be obtained for any strata, it is possible, as I have shown in another paper (24), to obtain a fairly-accurate estimate of the yield of wells and filter-galleries, the formula being based upon the data derived from experimental investigations of flow and pressure and from field-surveys. 92 MR. W. E. BALDWIX-WISEMAX OX [Feb. 1907, Before leaving the question of flow, it may be of some interest to record the mode of rupture of the chalk in the course of the ex- perimental investigations. At pressures of about 35 lbs. per square inch, pieces broke away from the under surface of the test-piece, leaving an apparently-dry surface, showing that the rupture was sudden ; for soon thereafter the percolating water spread over the whole surface in a moist film, on which the drops gathered before dropping into the collecting-pan. As the pressures were increased, other pieces of lesser size detached themselves from time to time, until at a pressure of 46 lbs. per square inch, the test-piece cracked near the centre of the unsupported circle of rock, through which crack an irregular jet of water passed. By introducing coloured water into the cylinder, I was able to stain the surfaces of this crack ; and, upon breaking up the test-piece, I found the crack to be irregular, but approximately vertical. Other test-pieces of chalk gave almost identical results, at similar or slightly higher pressures ; and it is possible that chalk-cliffs may in part be destroyed by the rupturing action of interstitial water at higher pressures than this. In experimenting upon the rate of flow of various solutions through capillary tubes, Girard (23) found that the rate of flow was largely affected by the strength and temperature of the solution and by the chemical composition of the dissolved salt. Thus, for instance, the velocity through equal lengths of tubes of the same diameter under the same difference of pressure varied, as shown in the follow- ing Table (VII) : — Table VII. Maid. Strength of solution. Tem%)erature in°C. Relative velocity, compared with that of water at 60° C. as unity. Water 1/6 J? 1/3 1/3 1/3 0 60 8 80 3 60 3 60 0 60 0875 1-000 0-774 2-907 0-465 1-653 0-678 2045 1-330 2-924 Solution of sugar Solution of common salt . Solution of saltpetre I conducted a series of observations on the flow of brine through a block of Bath weatherstone under various pressures ; but the data obtained were of little use, as neither the discharges nor the differ- ence of density of the solution before and after percolating through the block were at all constant under the same pressure, nor were the variations at different pressures at all comparable one with Vol. 6$.-\ THE MOTION OF SUB-SUEFACE WATER. 93 the other, nor with the discharges of pure water at corresponding pressures. As shown in the appended diagram (fig. 1), I found that the resulting effluent of a strong brine was, at first, almost entirely d.a rig. 1. Number of experiments. \«. ^ **1m^\ 115- / / ^^v ^ - — ,^<-««. £>--* / \ \ / \ \ 110- / / / \ \ \ \ \ 1-05- i.nn. • / / \ A Number of experiments. Density of solution before percolation. Density of effluent after percolation... 015 M 0-10- 0-05 0-00 005 0-10 015J Diagrams shewing the variation's in density of brine flowing through a block of Bath Weatherstone under various pressures. >^=f=^ Number of experiments cleared of all the salt in the solution ; but later, on using a weaker brine, I found that the effluent was a much stronger brine than the inflowing solution, deriving its salt from the pores of the rock. I experienced considerable difficulty in removing the salt from the pores, hot water and long-continued soaking failing to eliminate 94 MB. W. E. BALDWIN-WISEMAX OX [Feb. 1907. all traces of the salt long after the experiments had terminated: and the whole test was an excellent object-lesson of what may be expected when a water-bearing rock is overpumped in the vicinity of the sea — an experience which has been realized in more than one seaside resort deriving its water-supply from sub-surface sources. Also, for the reason that the temperature of a solution and the nature of the salt affect so radically the rate of flow, it seems to me. although this point has not previously received the attention that it deserves, to be most essential that the temperature and density of any underground stream should be recorded wherever and when- ever possible, as, without these data, experimental records are not directly comparable. III. ExPEBZtfEXTAL DATA OX YaELATIOX OF PbESSUBE IN THE IXTEBSTICES OF A ROCK. Various investigators have endeavoured to measure the basal area of the cone of depletion produced by any specific pumping in a locality, but not infrequently, owing to an insufficiency of data, the area of depletion has been very arbitrarily delimited. Prof. Boyd Dawkins, in his most interesting lecture, ' On the Relation of Geology to Engineering ' (1), to which I have pre- viously referred, gives a fairly lengthy list of measured cones of depletion in the Chalk; one of which, that produced when pumping 6-| million gallons a day at the Mill-dam Pumping Station of the Hull Corporation, is particularly interesting owing to the fullness of its detail. Eoadley (25) in the Maiden experiments very carefully investi- gated the rate of growth of a shallow cone of depletion, when steadily pumping 2300 gallons an hour for 10 hours from a 3-inch well through a l|-inch pipe. The difference of level in bores 5 feet 10 inches apart is shown in the following Table (Till) :- — Table VIII. No. of hours from the commencement. I>rop of level when pumping 2300 gallons an hour. At well. 5ft.lQirt3./roiHZCcll. 1 1 ft. 8 ins. from well. 1 2 2-23 2-38 2-48 2-53 2-58 2-61 262 264 2-66 267 0-52 067 0-75 0-81 0-84 0-86 0-89 092 0-94 097 0-49 065 073 079 0-81 0-84 0-86 3 4 5 6 7 8 0-89 9 o-yi 10 0-04 Vol. 63.] THE MOTION" OF SUB-SURFACE WATEE. 95 This table affords an interesting study of the increased rate of flow induced by a difference of pressure. At the outset, the inflow to the well being at normal velocity is not equal to the volume abstracted by the pumps, and a considerable central depression is produced. As the difference, however, in the volume of successive hourly cones is not a constant quantity, but the differences are related one to the other in a decremental ratio, it follows that the rate of inflow must steadily increase, since the quantity abstracted is fairly constant. Hoadley has also devised a neat piece of apparatus for experi- mentally determining in the laboratory the outline of the cone of depletion in sands of varying degrees of coarseness. Slichter assumes that the circumferences of concentric circles are crossed by equal amounts of water in the same time, and that therefore the velocity varies inversely as the distance from the axis of disturbance ; and he deduces a mathematical expression for the pressure at any point, at any distance from the well. He also evaluates the drop in pressure in a sandstone under a head of 10 feet at various distances from the well, somewhat as shown in the following Table (IX) :— Table IX. Distance from centre of well, Drop in pressure, in feet. in lbs. 0-25 10 0-54 9 1-19 8 2-58 7 5-62 6 1225 5 2667 4 57-52 3 126-50 2 275-50 1 I endeavoured to solve the question, upon the assumption that the outline of a transverse vertical section of the cone of depletion would be a curve, the coordinates of which would vary directly as the distance from the centre of disturbance, and as the rate of loss of unit-pressure at the several distances from that centre : the value for the basal radius of the cone of depletion being that distance from the centre of disturbance in the plane of the water-surface at which the loss of unit-pressure is zero, or at which the velocity of flow i& normal. I therefore made an experimental determination of the loss of pressure at each inch of depth below the surface of a cylinder of rock of certain thickness, when subjected to a considerable difference of pressure on its two surfaces : the upper surface being- subjected to various constant hydrostatic pressures, and the pressure on the lower side being atmospheric. The internal pressures were 06 ME. W. E. BALDWIN-WISEMAN OX [Feb. 1907, recorded at each inch of depth below the pressed surface by piezo- meter tubes, projecting radially into the rock-mass and closed at the outer end, the tubes being so arranged that no one tube inter- fered with the now past any other ; and results as shown in the following Table (X) were obtained as the averages of a large number of separate experiments : — Table X, showing the Pressure ih lbs. per Square Inch at various Depths from the pressed Surface in similar Thicknesses of Eock. i 1 Surface- Micheldever Chalk. Bradford Oolite. Hard Baresbury Sandstone. pressure in lbs. 1 I! persq.in. 1 in. 2 in. 3 in. 4 in. Sin. 1 in. 2 in. 6-3 Sin. 4 in. 5 in.1 lin. 5-4 4-4 3-6 6-0 2 in. 3 in. 4-9 41 4 in. 2-9 5 in. 10... 9-4 8-8 8-4 7-9 7 0 7*3 1-4 20 ... 18-9 17-7 16 8 15-9 14-2 14-9 12-9 11-1 9-2 7-4 12-0 9-9 82 5-8 2-7 30 ... 28-2 26-8 25-3 23-8 21-2 22-4 197 169 141 11-2 182 14-9 12-5 8-8 4-1 40 ... 37'6 35-2 33-6 31-8 283 30-0 26-1 22-6 187 15-0 24-1 20-0 16-4 11-7 5-5 50 ... ... 37*5 32-8 28-2 233 18-8 30'2 25-0 20-9 14-7 6-8 60 ... ... ... ... 45-2 39-7 34-0 28-2 22-7 36-1 30-0 25-1 17-8 8-2 70 1 ... ... ... 52-8 46-2 397 32-9 26-3 424 35-2 294 20-7 9-7 Table XI, showing average Loss of Unit-Pressure per Inch of Depth. Distance in inches from surface under pressure. Loss of unit-pressure per inch of depth in Micheldever Chalk. Bradford Oolite. Hard Baresbury ( Sandstone. 2 0-060 0-057 0-053 0-052 0-059 0-250 0-170 0-146 0-133 0-125 ! 0-396 0-250 0-194 0-176 0-173 3 4 5 If the difference between the surface-pressure and the pressures at the several depths be divided by the respective depths beneath the surface and by the corresponding surface-pressure, as shown in the preceding Table (XI), one has a directly-comparable rate of loss of pressure for each stone ; and it will be observed that there is a con- siderable difference in the rate of variation of pressure in the chalk and in the sandstone, the sides of the cone of depletion having a steeper rise in the immediate vicinity of the centre of disturbance for the chalk than for the sandstone. Curves which are plotted from data such as those embodied in the preceding table have a close resemblance to the outline of those cones of depletion that have Vol. 6$.~] THE MOTION OF SUB-SURFACE WATER. 97 been determined with some considerable degree of accuracy in the field ; and assuming, as Hoadley's experiments demonstrate, that the outlines of cones of depletion in the same strata are approximately similar, but vary in magnitude, as more or less parallel curves according to the duration and intensity of the pumping ; then it follows that, by adjusting the vertical scale of the diagram so that, in place of a difference of 1 lb. of pressure per square inch, it gives the pressure in lbs. per square inch corresponding to the difference of water-level at rest and when pumping, then a corre- sponding adjustment of the horizontal scale will at once afford data as to the variation of pressure with distance in the field, provided that the strata be uniform and of structure and texture similar to the structure and texture of the experimental test-piece : the diagram of loss of pressure then really becomes a scaled section of the cone of depletion. This method of graphic representation can be further applied, to afford an estimate of the percentage interference of two contiguous wells. IV. Field-Observations. Although numerous geologists and hydrologists have at various times conducted more or less extensive hydrological surveys, the question of the controlling factors of sub-surface flow has not received the full measure of attention that so important a subject deserves, and most of the papers which have been written deal rather with the shallow sub-surface waters of the gravels than with those of the older formations. Of the former division, two very interesting contributions are those in which Haas (26) points out the extreme irregularity of level of the water in the gravels of Eastern Schleswig-Holstein, owing to the restricted areas and very irregular disposition of the gravels in the Boulder-Clay of that district ; and in which Salbach (27) demonstrated, by trial-pumpings in the gravels of the "Rivers Elster, ISaale, and Elbe, that there was not only a considerable variation of level, but also of chemical composition of waters derived from bores, in close proximity to one another, let into the bed and banks of the stream respectively. In the latter division, Chalon (28), Paramelle (29), Lueger (30), and other writers have contributed not a few data on the influence of surface-configura- tion and of the disposition of the impervious substratum forming the base of the water-charged rocks. These writers in general state that the levels of the underground waters vary on the whole directly with the surface-configuration, and that the lines of sub- surface flow are mainly coincident with those of the surface- drainage. But the theorem is not so obviously apparent : for, although the areas of greatest surface-elevation of a permeable rock may, and most probably will be, areas of high sub-surface water-level, still it does not universally follow that the drainage- lines of both systems will also be coincident ; as the agencies which give rise to the formation of surface drainage-lines are not Q. J. (i. S. No. 249. k O 00 « K CO CO l>- Ci k? « Ci Ci Ci o Kl 00 CO 00 00 ! ■"* I— 1 1—1 '"", ^ H-l CO CO ■* o 8 8 8 JN CO CO iO Ci Ci O Ci co co c: co n « ffl o © Ci o CO o «o 1^ 5s <5 ^1 ,£i © l> o »c I- CO i-i lO CO — ^ , V* IWeston,' .-ftp • l^ Luton — , — «ft^ @ Bunting-ford Cottered ^\v% ^ ^ •Walkern I btevenage '® St. Paul's Waldcn Dunstable Scale: 8 miles to an inch. Notes: Subsurface water-levels referred to Ordnance Datum shewn thus — -»— i» Line of outcrop of Gault-clay shewn thus j&&&&%% Line of outcrop of Greemand not shewn. Fig. 3. Sketch -Map shewing the outcrop of the Gauit and subsurface water- contours in the Chalk «*„•.. 0 Swindon j.^Bishopstonc .0? of WILTSHIRE /^ Market ™Lavington 0 Rush all O ' Warminster Heytesbury ^Tilshead Notes: Subsurface water-levels referred to Ordnance Latum shewn thus ^V25£x Line of outcrop of Gault-clay thus... Line of outcrop of Greemand not shewn. Vol. 6$.~] THE MOTION OF SUB-SURFACE WATER. 103 Chalgrave, Todditigton, Shitlington, and Stondon ; while, in the latter county, the sub-surface water-contours in the area to the north and west of Marlborough have their axes parallel to the line of outcrop of the Gault-Clay, which ranges by the foot of the Chalk- hills through Compton Basset, Clyffe Pypard, Wroughton, and Bishopstone. A similar parallelism can also be traced in the north- western extremity of the Salisbury-Plain area : the Contour-lines being roughly parallel to the line of outcrop of the Gault-Clay, ranging by Dilton Marsh and Coulston. Finally, if the homogeneous stratum be replaced by one of varying texture and porosity, then the contour-lines, while still retaining a rough parallelism, will be indented or prolonged to a degree proportional to the structural variation of the strata in that locality. If, on the other hand, it be faulted, the faults may either tend to lower locally the water-level by providing freer outlets along the lines of rupture, or else raise it by interposing a more or less efficient dam across the line of flow ; as in the instances previously quoted, the percentage-porosity of a porous stratum may be locally affected by the faulting. It is thus possible, by a careful study of the hydrological map of a district which has been surveyed with some exactitude, to gain a considerable know- ledge of the details of the geological structure of that district which might not be otherwise available, while, at the same time, affording valuable data for the scientific solution of the water- supply and other water-problems of that district. V. Bibliography. 1. W. Boyd Dawktns. 'On the Relation of Geology to Engineering' [James- Forrest Lecture] Min. Proc. Inst. C. E. vol. cxxxiv (1898) pp. 255 et seqq. 2. W. Bland. ' On the Influence of Season over the Depth of Water in Wells ' Proc. Geol. Soc. vol. i (1831) pp. 339-40; also Phil. Mag. & Ann. Phil. n. s. vol. xi (1832) pp. 88-96. 3. W. Boyd Dawkins. Op. supra cit. Min. Proc. Inst. C. E. vol. cxxxiv (1898) p. 260. 4. I. Roberts. ' On the Wells & Water of Liverpool ' Proc. Liverpool Geol. Soc. 1868-1869, pp. 84-97; also liep. Brit. Assoc. 1883 (Southport) p. 405 ; and C. E. De Rance. ' The Water-Supply of England & Wales ' p. 17 (London, 1882). 5. H. Daect. ' Les Fontaines publiques de la Ville de Lyon ' Paris, 1856. 6. — Hagen. ' Handbuch der Wasserbaukunst ' Berlin, 1869. 7. F. Seelheim. ' Methoden zur Bestimmung der Durchlassigkeit des Bodens ' Zeitschr. fur Analytische Chemie, vol. xix (1880) pp. 387-418. 8. Allen Hazen. Report of the Massachusetts State Board of Health, 1892, p. 541. 9. C. H. Wolff. ' Water ' vol. viii (1906) p. 134. 10. C. S. Slichtee. 'The Motions of Underground Waters' Bull. No. 67, U.S. Geol. Surv. Water-Supply & Irrig. Papers, 1902. 11. F. H. King. 19th Annual Report U. S. Geol. Surv. 1898-99, pt. ii, p. 59. 12. C. C. Mooee. Proc. Liverpool Geol. Soc. vol. xi, pt. ii (1902) pp. 133 et seqq. 13. Report of the Royal Commission on the Stone to be used for the Houses of Parliament, 1839. 14. B. Latham. Brit. Assoc. Rep. 1881 (York) p. 614, and 1883 (Southport) p. 495 ; and ' Croydon Bourne-Flows ' Proc. & Trans. Croydon Nat. Hist. Soc. 1904 ["Special Supplem. 44 pp.] 15. K. Honda. ' Water,' vol. vii (1905) p. 238. 16. M. D. Pantanelli. Ibid. vol. vi (1904) p. 37. 17. F. Wetde. Ibid. p. 151. 104 JJK. W. R. BALI) WIN- WISEMAN ON [Feb. I907, 18. J. LrcAS. ' Hydrogeology : one of the Developments of Modern Practical Geology ' Trans. Surveyors' Inst. vol. ix (1877) pp. 153-77 ; & ' The Hydro- logy of Middlesex & part of Hertfordshire ' vol. x (1878) pp. 279-301. 19. 0. Reynolds. 'An Experimental Investigation of the Circumstances which determine whether the Motion of Water shall be Direct or Sinuous, &c.' Phil. Trans. Roy. Soc. vol. clxxiv (1883) pp. 935-82. 20. R. Cohen. ' Ueber den Einfiuss des Druckes auf die Viskositat von Fliissig- keiten ' Annal. d. Physik & Chemie, n. s. vol. xlv (1892) pp. 666-84 21. E. Wollny. ' Untersuchungen iiber die Permeabilitat des Bodens fur Wasser ' Forschungen auf dem Gebiete der Agrikulturphysik, vol. xiv (1891) pp. 1-28. 22. Archiv fur Hygiene, vol. ii (1884) p. 499. 23. Jamik. 'Cours de Physique de TEcole Poly technique,' 3rd ed. (1891) vol. i, pt. ii, p. 124. 24. W. R. Baldwin- Wiseman. 'The Flow of Underground Water ' Min. Proc. Inst. C. E. vol. clxv (1906) p. 309. 25. J. C. Hoadlet. Proc. Soc. Arts, Boston, 1882-83, p. 115. 26. — Haas. ' Der Wasserbau ' Leipzig, vol. i. 27. B. Salbach. ' Experiences had during the last twenty-five years with Water- works having an Underground Source of Supply' Trans. Am. Soc. Civ. Eng. vol. xxx (1893) pp. 293-329. 28. P. Chalon. 'Sur la Recherche des Eaux Souterraines ' M^m. Soc. Ing. Civ. France, vol. ii (1897) pp. 38-91. 29. L'Ahbs Paeamelle. 'L'Art de Pecouvrir les Sources ' Paris, 1896, p. 158. 30. O. Luegee. ' Wasserveisorgung der Stadte ' 1903. EXPLANATION OE PLATE V. Hydrological map of Dorset, Wiltshire, and Hampshire, on the scale of 4 miles to the inch. Discussion. Sir John Evans said that they were very much indebted to the Author for his observations. With regard to the Chalk, permeability depended not so much on the nature of the Chalk itself as on the fissures by which it was traversed. The angle of friction determined the flow of streams above ground as well as below; thus, in the case of the Gade and the Bulbourne, the inclination of the stream was 125 feet to the mile near Watford, but in other localities nearer the base of the Chalk, where it became more clayey, the inclination was 19-5 feet to the mile, and near Dover 40 feet to the mile. Mr. W. Whitaker commented on the great practical as well as theoretical value of such papers as that brought forward by the Author. Mr. Cpnningham-Craig said that he could fully endorse the previous speakers remarks as to the usefulness of information of this kind, especially in connexion with water-supply in the tropics. If the Author's points were more fully and frequently present to the minds of geologists, the provision of water for small communities in tropical regions would be greatly facilitated. Mr. GL W. Young enquired the precise meaning attached by the Author to the word porosity. Was it the total amount that the rock would absorb, or the amount absorbed within some given time ? Mr. W. Baldwin said that he would like to ask the Author whether he had made any experiments showing how variation of pressure would affect the porosity of various rocks. p-v"'-. p ;;"->'V-:' HI sssy/is. SKETCH-MAP showing SUBSURFACE WATER-LEVELS IN THE CHALK OF DORSET. WILTSHIRE^ HAMPSHIRE fcX Sru . ^-^umonouth-SlgSS!,' f h^^t^C^ ~I) DE. A. SMITH W00DWABD OX [^lay I907, latter period. The unique tooth of Acrodus nitidus is very small, and belongs to a diminutive shark like that indicated by the equally- small teeth of Acrodus ornatus from the Wealden of the Isle of Wight. The vertebrate fossils, therefore, confirm Hartt's determina- tion of the Bahia estuarine deposits as referable to the beginning of the Cretaceous Period. It is certainly disappointing to find that at that time the land in the South- American region was as destitute of mammalian life as the continent in the Northern Hemisphere drained by the river which deposited the VTealden formation of Western Europe. EXPLANATION OF PLATES VI-VIII. Plate VI. Figs, la & lb. Goniopkolis Hartii (Marsh) ; the greater portion of the mandibular symphysis, oral aspect (1 a), with anterior expansion (1 b) seen from below, one-quarter of the natural size. — Setiibal. [Brit. Mas., No. E 3423.] Fig. 2. Ditto ; incomplete dorsal scute, outer aspect, showing the antero- external peg, one-quarter of tbe natural size. — Ponta de Tinuaba. Ilha Mare. [Brit. Mus., Ho. E 3224.] 3. Steneosaarus sp.; dorsal scute, outer aspect, showing the antero- external peg. three-quarters of the natural size. — Oxford Clay; Peterborough. [Collection of Alfred N. Leeds, Esq.; F.G.S.] Figs. 4 & 5. Belonostomtis (?) carinatas, sp. nor. ; scales, partly broken, probably of the caudal region, natural size. — Itaearanha. [Brit. Mus.. No. P 10062.] Plate VII. Fig. 1. Mawsoma gigas. gen. et sp. nov. ; remains of skull and mandible, right lateral aspect (type-specimen). [Brit. Mus.. No. P 10355.] 2. Ditto ; left frontal of the same specimen, outer aspect. 3. Ditto: left quadrate of the same specimen, outer aspect. Figs. 4 a & 4 b. Ditto ; right parietal of another specimen, outer aspect (4 a),. with (4 6) transverse section of edge of bone, showing overhanging outer lamina, natural size. [Brit. Mus., No. P 10356.] ag. := angular ; art. = articular ; hr. = displaced branchial arches; go. = coronoid ; or. = cranium ; hm. = top of hyomandibular ; ot. = otic region ; pas. = parasphenoid ; pit. = front end of ectopterygoid ; pts. = pterygo- suspensorial plate ; qu. = quadrate. Plate VIII. Figs. 1 a & lb. Mawsonia gig as, gen. et sp. nov. ; left articular of type-specimen, outer (a) and (b) condylar aspects. Fig. 2. Ditto ; posterior end of the left mandibular ramus of the same specimen, outer aspect, showing the meckelian ossification (m.) projecting beyond the angular bone (ag.). 3. Ditto ; left coronoid of the same specimen, inner aspect, showing the granular teeth and facette (J.) for the overlap of the splenial. Figs. 4 a & 4 6. Ditto ; portion of ectopterygoid of the same specimen (4 a) inner aspect, natural size, and (4tb) some teeth enlarged 15 times. Fig. 5. Ditto ; gular plate of the same specimen, outer aspect. 6. Ditto ; portion of right operculum, outer aspect, showing place of suspension (s.). [Brit. Mus.. No. P 10357.] Quart. Joum. Geol. Soc.Vol. LXIII.P1.VI. J A.H. Searle del. et litt. Bale & Danielssou,I# imp. Figs. 1 8c 2. GONIOPHOLIS HARTTI. Fig. 3. STENEOSAURUS. Figs. 4. & 5. BELONOSTOMUS (?) CARINATUS. Quart. Journ.Geol.Soc. Vol. LXIE.Pl. VII. b' +3 £ R CD "00 o Quart. Journ. Geol. Soc. Vol. DOE, PI. VIE. ag. 4^b.xl5 5.X3 A.H.Searle deLetlith. Bale &Daiaelsscm,LUinip Figs. 1-6 MAWSONIA GIGAS. Figs. 7 & 8 MACROPOMA MANTELLI. . Yol. 63.] THE CRETACEOUS FORMATION OF BAHIA. 139 Fig. 7. Macropoma Mantelli, Agass. ; portion of the left mandibular ramus, outer aspect, showing articular {art.) and angular (ag.) bones, natural size.— English Chalk. [Brit. Mus., No. P 6454.] 8. Ditto ; portion of the left mandibular ramus, outer aspect, showing the meckelian ossification (m.) projecting beyond the angular bone (ag.), and the quadrate (qu.) in position, natural size. [Brit. Mus., No. 49094.] [Unless otherwise stated, all the figures on Plates VII & VIII are drawn of one-third the natural size.] Discussion. Mr. E. T. Netvton congratulated one of the two Authors on the interesting and valuable material which he had collected, and the other upon the admirable use which he had made of this material ; especially in regard to the monster Coelacanth fish, the structure of which had been so clearly pointed out to the Eellows present. Mr. Lydekker, after referring to the possible bearing of the paper on the evolution of the Crocodilia and on continental connexions and disconnexions, congratulated the Authors on the result of their work. Mr. R. B. Newton, in thanking the Authors for their valuable paper, stated that Mr. Mawson's collections contained some interesting molluscan remains, among which were a number of Anodont — or Unioniform — shells suggestive of Unio porrectus and U. antiquus of British Wealden areas, associated with Vivijpara- and Melania-like gasteropods, all of which had been studied by Prof. Hartt and later by Dr. C. A. "White, both being of opinion that they belonged to the Lower Cretaceous. The vertebrate evidence now brought forward by Dr. A. S. Woodward, especially the newly-recorded occurrence of Goniopholis, together with the Lepidotus-sc&les originally determined by Egerton, was strong confirmation as to the Lower Cretaceous age of these deposits. Contrary to these views, it might be mentioned that Prof. A. de Lapparent's ' Geologie ' contains a statement to the effect that the fauna of these freshwater deposits of Bahia shows resemblances to that which characterizes the Laramie Beds of North America. Dr. C. W. Andrews congratulated the Authors on the valuable results that had been attained through the long and patient col- lecting carried out by Mr. Mawson. He enquired whether any crocodilian vertebras showing traces of a form intermediate between the earlier amphiccelian and the later procoelian types had been found, since it was about this horizon that the transition between the two must have occurred. In fact, intermediate forms had already been described in the vertebras of Goniopholid crocodiles from the Lower Cretaceous in North America. Dr. Smith Woodward apologized for the absence of Mr. Mawson, and briefly replied. The only vertebral centra that he had observed which might be crocodilian were typically amphiccelous. l 2 140 DE. A. SMITH WOODWABD ON [May I907, 10. On a New Dinosaueian Reptile (Scleromochlus Taylobi, gen. et sp. nov.) from the Teias of Lossiemouth, Elgin. By Aethue Smith Woodward, LLJD., F.R.S., F.L.S., E.G.S., Keeper of the Department of Geology in the British Museum (Natural History). (Read January 9th, 1907.) [Plate IX.] Although so many types of reptiles have been obtained during recent years * from the Triassic sandstones of Elgin, Mr. William Taylor has lately discovered two examples of a new form which represents still another group. Through his kindness I have had the privilege of studying these two specimens and comparing them with two more imperfect skeletons of the same animal, which occur on a slab of Elgin Sandstone in the late Mr. James Grant's collection, now in the British Museum (No. R 3146). All the specimens show merely impressions of bones in the rock, but they occur in counterpart slabs, and many of their most important features can be readily understood with the aid of wax-squeezes taken from the cavities. The four individuals of this new reptile already known are approximately of the same size, each measuring about a decimetre in length to the root of the tail, which is long and slender. They therefore represent a comparatively-diminutive species ; and the lightness of the skeleton, with its hollow bones, suggests an animal of remarkable agility (see the accompanying text-figure, p. 141). The head is relatively large, and the neck short. The fore-limbs are small and delicate ; while the hind-limbs are very large, and evidently adapted for a bipedal running or leaping gait. The more important measurements, in millimetres, are as follows : — Length of head 32 ,, presacral vertebral column 53 „ scapula 10 „ humerus 19 „ radius and ulna 19 ,, longest digit of inanus 5 „ ilium (an tero-posterior) 10 „ femur 30 „ tibia and fibula 34 „ metatarsus 17 ,, proximal phalanges of pes 4 ,, longest digit of pes (approximate) 12 1 E. T. Newton, 'On Some New Eeptiles from the Elgin Sandstones ' Phil. Trans. Roy. Soc. ser. B, vol. clxxxiv (1893) p. 431 ; and ' Eeptiles from the Elgin Sandstone — Description of Two New Genera ' ibid. vol. clxxxv (1894) p. 573 ; G. A. Boulenger, ' On Reptilian Remains from the Trias of Elgin ' ibid. vol. cxcvi (1903) p. 175 ; and ' On the Characters & Affinities of the Triassic Reptile Telerpeton elginense' Proc. Zool. Soc. 1904, vol. i, pp. 470-81 & pis. xxx-xxxii. To the last paper Mr. William Taylor contributes a complete list of the known Triassic Reptiles from the Elgin district, with an account of their distribution. Yol. 6$.~] A NEW DIN0SAT7RIAN REPTILE. 141 Outline-restoration of the skeleton 0/ Scleromochlus Taylori, natural size, with two digits of the manus hypothetically added, and the abdominal ribs omitted. — Trias ; Lossiemouth, Elgin. 142 DR. A. SMITH WOODWARD ON [May I907, The large head viewed from above or below, as in the type- specimen (PI. IX, fig. 1), is elongate- triangular in shape, with a sharply-pointed snout. None of its external bones are sculptured. The orbit (orb.) and the antorbital vacuity are very large, as shown best in one of the British Museum specimens (PI. IX, fig. 2) ; and a small, separate, lateral narial opening appears to be distinguishable in the type. The interorbital region is very narrow. No traces of teeth are seen in any specimen : hence it is probable that they were inconspicuous or absent. Apart from the dentition, the general aspect of the skull must have been much like that of the Elgin Ornithosuchus or the American Triassic Anchisaurus. The presacral vertebras are preserved in regular sequence in the type-specimen, and are about 21 in total number. The centra are slightly constricted, and not much longer than wide ; each slender neural spine has a basal extent nearly equalling the length of the centrum to which it belongs. Seven vertebrae may be reckoned as cervical, but it is not certain whether they bore ribs. The thoracic ribs are slender and gently curved. Four vertebrae, of the same size as the preceding, are comprised within the extent of the ilium (il.), and each bears a pair of broad transverse processes or sacral ribs. The anterior caudal vertebrae, well seen in the type-specimen, are also equally large, and at least four of them bear broad transverse processes. The chevron-bones, of which some are seen scattered in Mr. Taylor's second fossil (PL IX, fig. 35), are delicate and not much elongated, with the ascending arms not united above by a bridge of bone. The terminal caudal vertebrae, which occur in short series in the same specimen, are much attenuated, and indicate that the tail was long and slender (PI. IX, fig. 3 a). The scapula, which is most satisfactorily shown in the British Museum specimen (PI. IX, fig. 2, sc), is a narrow slender blade, with the distal end scarcely expanded. Its length equals that of three to four anterior dorsal vertebrae. The humerus (Ji) is very slender, as long as the fore-arm (r), and not much expanded at the upper end. The manus is indistinctly exhibited and probably incomplete in the type-specimen, but traces of three slender digits are preserved. The hollows in the fossil left by the pelvis cannot be exactly interpreted. It may only be stated that the ilium is antero-posteriorly extended for the length of four vertebrae ; that the pubis, which slopes downward and forward, is not rod-shaped, but expanded into a narrow lamina which tends towards meeting its fellow of the opposite side in the median line ; and that the ischium is a comparatively-thick rod (as shown on the left side of Mr. Taylor's second fossil). A bar of matrix on both sides of the type-specimen and appearances in the second fossil suggest that the acetabulum was perforate, but this is not certain. The femur (/) is nearly straight, and very little shorter than the tibia. The cnemial crest of the tibia (t\ as best seen in Mr. Taylor's second specimen, is not very prominent; and the large size of the internal cavity of this bone is well shown by its infilling, preserved on the right side of the type-specimen. The fibula is very slender, though Vol. 6$.~] A. NEW DINOSAUEIAN REPTILE. 143 complete, and is always found in undisturbed contact with the tibia. The tarsal bones are obscure in all cases, but they are scattered in the second specimen, and one of them (PI. IX, rig. 4) is remarkably similar to the elongated calcaneum discovered by Marsh in Hallopus. The metatarsus (mt.), which is conspicuous in all the fossils, is half as long as the tibia, and consists of four slender elements, of approximately equal length, firmly fixed together. At least, these four bones always lie in close contact in perfectly-parallel order, however much the foot may be crushed and displaced. On the outer side of the proximal end of the metatarsus of the left hind-foot in the type-specimen, there is the impression of a small bone which appears to be a rudimentary fifth metatarsal, although it may be only a displaced tarsal. Three of the proximal phalanges of the foot (p) occur well separated by matrix in both Mr. Taylor's specimens, and the longest toe in the type- specimen clearly comprises five phalanges, of which the terminal is a pointed claw. There are no traces of dermal armour, but an impression of the abdominal wall is distinctly preserved in the British-Museum specimen (PI. IX, fig. 2), owing to the fact that it is strengthened with a plastron of closely-arranged abdominal ribs (abd.). The bones are very slender, much more delicate than the thoracic ribs, and are seen again, although scattered and displaced forwards, in Mr. Taylor's second specimen. All the characters of the skeleton which have not been enumerated in the foregoing pages are more or less doubtful, and among these are unfortunately some of fundamental importance for the deter- mination of the affinities of the new animal. As originally pointed out to me by Mr. William Taylor, when he showed me the fossils, the extreme lightness of the whole skeleton and the peculiar mechanical adaptation of the hind limbs suggest comparisons with a bird; but the observable parts of the head, fore-limbs, and pubis prove that the animal is a reptile. Among reptiles, it can only be compared with the B.hynchosauria, Parasuchia, and Dinosauria; but lack of know- ledge, especially of the pectoral arch below the scapula, prevents determination by strict rule. The pelvis is very different from that of the known Rhynchosaurians ; while the absence of bony armour and the apparent perforation of the pelvic acetabulum distinguish the animal from the ordinary Parasuchia. So far as preserved, how- ever, most of the characters agree well with those of the Dinosauria, especially the American Triassic genera described by Marsh.1 Compared with the latter, the new Elgin fossil is remarkable for the relatively-large size of the head, the apparently-toothless jaws, and the firm union of four long metatarsal bones in the foot. "These are the characters of a hitherto unknown genus, which may be named ScleromGchlus ('hard fulcrum'); the type-species being 1 Anchisaurus, Ammosaurus, and Hallopus, Marsh, ' The Dinosaurs of North America ' 16th Ann. Rep. U.S. Geol. Surv. 1894-95, pt. i [1896] pp. 147-55 & pis. ii-iv, vi. Hallopus is regarded as Lower Jurassic bv Marsh, but referred to the Trias by Williston, Journ. Geol. Chicago, vol. xiii (1905) p. 338. 144 A NEW DIN0S1UEIAN EEPTILE. [May'1907, the small Scleromochlus Taylori now described. For a geological period so remote as the Trias, the high degree of specialization of this diminutive Dinosaur is truly astonishing. EXPLANATION OF PLATE IX. Seleromochlus Taylori, gen. et sp, nov. ; impressions of parts of the skeleton. — Trias ; Lossiemouth, Elgin. Fig. 1. Type -skeleton, impression seen from below, natural size. [William Taylor Collection.] 2. Portions of two skeletons, one showing the plastron of fine abdominal ribs, natural size. [James Grant Collection, Brit. Mus. No. R 3146.] Figs. 3 a & 3 b. Portions of tail (3 a), with (3 b) scattered chevron-bones, 3 times the natural size. [William Taylor Collection, No. 2.] Fig. 4. Wax-impression of the supposed calcaneum, natural size. [Same specimen.] 5. Wax-impression of part of the right hind-foot, natural size. [Type- specimen.] abd. = abdominal ribs ; / = femur ; h = humerus ; it. = ilium ; mt. = meta- tarsus ; orb. = orbit ; p = proximal phalanges of hind-foot ; r = radius and ulna ; sc. = scapula ; t = tibia and fibula. Discussion. Mr. E. T. Newton alluded to the extreme interest attaching to any new fossils from the Elgin Sandstones that might throw additional light upon the age of those deposits, a point which stili needed closer investigation. He also spoke of the difficulty that attended the working-out of these small Elgin reptiles, and warmly commended the masterly manner in which the Author had accomplished his task. The reference of these small specimens to the Dinosauria would, he thought, prove to be correct. Dr. C. W. Andeews remarked upon the extremely-high degree of specialization that had been attained by the various groups of Triassic Keptiles, and suggested that the form now under discussion might have been adapted for leaping, a mode of progression common among animals inhabiting desertic or, at least, sandy country, a good instance being the Jerboas, in which also the metatarsals were fused. The view that was expressed by one speaker, that this reptile might have been a predecessor of the Birds, seemed to be negatived by the extreme reduction of the fore-limbs and the absence of teeth. Mr. A. P. Young wished to ask whether anything in the skeleton suggested that the animal was fitted for a gliding flight, by means of an extended membrane, as seen in the flying squirrels of Southern India. The Authoe, in reply, admitted the remarkable resemblance between several parts of the new skeleton and the corresponding parts of birds, but he did not think that the affinities of the animal were closely Avian. He saw no evidence in the skeleton for the belief that any of the soft parts were arranged for gliding through the air. Quart. Joum.Geol.Soc. Vol. LXIII.PLK. v. V 36. x3 IV or l r B abdb. 3CL.X3 . r. --■7- K.~~~? :!i f.- t.- A.H.Seaxle del.et litk. B ale & D amels son ,L*4 nn]i SCLEROMOCHLUS TAYLORI Vol. 63.] CHANGES OF PHYSICAL CONSTANTS IN MINERALS, ETC. 145 11. On Changes of Physical Constants which take place in certain Minerals and Igneous Rocks, on the Passage from the Crystalline to the Glassy State ; with a short Note on Eutectic Mixtures. By James Archibald Douglas, B.A., F.G.S., Burdett-Coutts Scholar in the University of Oxford. (Read March 13th, 1907.) The effect of high temperatures on minerals and igneous rocks has long been a subject of geological research. De Saussure, in 1779, was the first to remark the fact that igneous rocks diminished in density on fusion, and became converted into a glassy substance. Further investigations as to these phenomena were made by Dolomieu in 1788, Sir James Hall in 1790, Magnus in 1831, and Bischof in 1841. The work of these early observers inspired Delesse in 1846 to publish an important paper on the glasses formed by the fusion of igneous rocks. This paper gives a good idea of the methods employed, at a time when electrical heating was an unknown factor in scientific research. With the improved appliances of modern science, the number of investigators has so greatly increased that it is only possible to mention the more recent researches ofQ Barus, Dcelter, Joly, Teall, Cusack, Bakhuis B/Oozeboom, Yogt, Akerinan, Allen, and Day. At the present time, every well-appointed laboratory has its electrical installation, and high temperatures may thereby be easily attained. As I had a strong current at my disposal, Prof. Sollas suggested that I should melt certain minerals and igneous rocks by means of a simple platinum-resistance, and endeavour to redetermine the change of specific gravity which accompanies their fusion. In the following paper I have given a brief account o£ some experiments on the fusion of igneous rocks, and the determination of their specific gravities in the glassy state ; I have also added a few observations on the thermal properties of the felspars, and an attempt to determine experimentally the existence of eutectic mixtures of quartz and orthoclase, and orthoclase and albite. Before proceeding with an account of my apparatus, it may be advisable to give a short summary of the methods employed by Delesse (4)1 in his memoir of 1846, as no important paper on the glasses of igneous rocks seems to have been published since then. Somewhat less than a cubic decimetre of the rock to be examined was crushed up and placed in a Hessian crucible, which was heated, at first gradually, and finally with a sudden increase of temperature, in an ordinary glass-furnace to a temperature about the melting- point of orthoclase. After some time, the crucible was withdrawn from the furnace and allowed to cool rapidly, the product of the fusion being in the form of glass. This glass, after being removed from the crucible, was crushed and its specific gravity was measured 1 Numerals in parentheses throughout this paper refer to the Bibliographical List, p. 160. 146 MK. J. A. DOUGLAS ON CHANGES OP PHYSICAL [May I907, in a specific- gravity flask. Thus the percentage-increase in volume of the rock on becoming glass could be calculated. The objections which maybe brought forward against this method are the following : — (1) In dealing with a cubic decimetre of the rock, the whole may not have become completely fused. This possibility would be greatly increased if the rock were not reduced to the finest powder, as appears to have been tbe case since it was at first slowly heated to prevent the projection of chips. The following description seems to suggest incomplete fusion: — 'Tantot le verre est parfaitement homogene, tantot au contraire, ainsi que de Saussure l'avait deja remarque, on y observe de petits squelettes blancs formes de quartz et quelquefois de feldspatb, qui ne se dissolvent pas dans la masse.' (Op. cit. p. 1386.) (2) Kesearches on the synthesis of minerals have shown that very rapid cooling is necessary to obtain a perfectly-homogeneous glass. This, I imagine, is only possible where the bulk of the glass to be cooled is very minute. (3) The whole of the glass may not have been of the same composition. Dr. J. Morozewicz has described how, when melting a granite of specific gravity 2-716, he obtained a glass, the specific gravity of which varied from 2*238 in the upper layers to 2*484 in the lower ; the silica being more abundant at the surface. (Tscherm. Min. & Petr. Mitth. vol. xviii, 1898-99, pp. 1-90, 105-240.) (4) The molten glass had an action on the crucible. To use Delesse's own words : — e II faut cependant faire exception pour les roches riches en mica, ainsi que pour les roches volcaniques qui corrodent fortement les creusets et peuvent les percer.' (Op. cit. p. 1382.) Dr. Morozewicz has also experienced the same difficulty when dealing with molten solutions in clay-crucibles. (Neues Jahrb. vol. ii, 1893, p. 42.) Bischof, moreover, has described how, after adding 30 per cent, of clay-slate to a fused lava, he still obtained a perfectly-clear and homogeneous glass (' Chem. & Phys. Geologie ' Suppl. 1871, p. 98). Delesse's glasses, then, may have attacked the crucibles to a greater extent than he imagined. (5) There appears to exist no means of testing the accuracy of the method employed in taking the specific gravity of the glasses, which, although crushed, were full of bubbles. In the present research I have tried to eliminate, as far as possible, these sources of error by finely powdering the rock in an agate mortar, and melting only a very small quantity ; by using platinum which is not attacked by the molten glass ; by the instan- taneous cooling possible with electrical heating ; and by taking the specific gravities of the glasses in a diffusion-column of heavy fluids: to obtain good results with these necessitates the glasses being free from bubbles and perfectly homogeneous. The apparatus 1 used in melting the rocks was very simple in construction. It consisted of a short length of platinum- ribbon, held by two horizontal brass-clamps which were 2 centimetres apart ; these were supported by vertical pillars on a bed of slate, 2\ cms. thick, which acted as a complete insulator preventing any leakage of current. The ribbon was 7 millimetres broad, and a length of about 3 centimetres was used for each experiment; it 1 The apparatus is similar to that suggested by Prof. Joly ' On the Volume- Change of Pocks & Minerals attending Fusion ' Trans. Poy. Dublin Soc. ser 2, vol. vi (1897-98) p. 283. Yol. 63.] CONSTANTS IN MINERALS AND IGNEOUS ROCKS. 147 was bent midway between the clamps into a loop, in which the substance to be melted was placed. The wires conveying the current from the switchboard were connected to two binding-screws which were attached by copper-strips to the base of the pillars (see fig. 1). The current, which was taken directly from the mains at 100 volts, was reduced to a suitable strength by means of German- silver wire-resistances. These resistances were in the form of long spiral coils, and were enclosed in a perforated-zinc case. The latter allowed free access of air, as it was necessary to prevent heating as far as possible : for, when the wires became hot, their resistance increased, and consequently there was a diminution in Fig. 1. — Apparatus used for melting igneous rocks, by means of an electric current. the strength of the current. German silver was used for the coils, in the place of galvanized iron, owing to the limited space ; the latter, however, is more suitable, as it becomes heated less readily and is far cheaper. The total resistance in the circuit when cold was about 12*5 ohms, and ranged down to 2-32 ohms. The switchboard was calibrated to give from 8| to 43 amperes, the last few studs being graduated in fractions of an ampere, so that a careful adjustment of the temperature was possible when nearing the fusion-point of the platinum, the ribbon usually becoming white- hot at about 40 amperes. The method of procedure was as follows : — The specific gravity of a fresh specimen of the rock to be 148 ME. J. A. DOUGLAS ON CHANGES OF PHYSICAL [May 1907, examined was first determined by means of a ' "Walker's balance,' two or three readings being taken in every case. A portion of the rock, about the size of an acorn, was then crushed in a steel mortar, passed through a fine copper sieve, and subsequently ground to the finest powder in an agate mortar. A sample of this powder was then placed in the loop of the platinum-furnace, and subjected to a temperature just below the fusion-point of platinum. After some time, the current was switched off, and the molten rock instantaneously solidified as glass, which, on the platinum-loop being pulled out, peeled off in the form of a flake ; it was then crushed, and examined microscopically under crossed nicols. If found not to be perfectly homogeneous, it was remelted until all traces of crystalline particles had disappeared. When the fusion was found to be complete, the glass was gently broken up in a small steel mortar, care being taken not to grind it up into too fine a powder. It was then passed through a small copper sieve, with a mesh of 12 to the square millimetre. The sieve was so constructed, that a fresh piece of copper-gauze could be used for each rock. The specific gravity of the glass was then determined by means of a diffusion- column of heavy fluids. The diffusion-columns were made from hard glass-tubing, of f-inch bore, cut into lengths of about 9 inches. It was found extremely important to clean and dry thoroughly each tube before use, as the powdered glass readily adhered to its surface. Strong sulphuric acid, absolute alcohol, and benzol were found quite efficient for this pupose. When the tube had been cleaned, its lower end was sealed up in the blowpipe-flame. The construction of a diffusion-column is too well-known to need description, but it may be noted that the powdered glass was always poured in before the fluids, as the latter, by moistening the sides of the tube, caused the fine particles to stick to the surface of the glass, and allowed only a small proportion to enter the column. The fluids employed were carbon-tetrachloride and methylene- iodide, and the indices were small glass beads, the specific gravities of which had been determined to the third place of decimals. These were dropped into the column after the glass had risen and formed a zone. The top of the tube was then sealed in the blowpipe-flame, so that little or no evaporation took place and the diffusion was very slow. The positions of the beads and glass-zone in each column, which were read by the aid of a horizontal travelling microscope, were then plotted on a curve. When the diffusion was complete the beads, if accurate, lay on a straight line ; a week or more often elapsed before this took place, so that the zone of glass could be carefully watched. In cases where the curve did not eventually become a straight line, the beads were redetermined and subsequent cor- rections made. The powdered glass usually settled into a well- defined zone, the specific gravity of which could be determined by insertion on the curve formed by the indices. Yol. 6^.~] CONSTANTS IN MINERALS AND IGNEOUS ROCKS. 149 "When the final reading had been made, the top of the tube was broken off, and the glass and beads were collected on a filter-paper. They were then washed with carbon-tetrachloride and afterwards with alcohol, the glass being preserved for further investigation. After crushing, the glass appeared to be almost entirely free from bubbles ; if, however, any remained, the fragments enclosing them rose somewhat above the general level of the zone, and could be neglected. In the same way, any unfused crystalline particles would tend to sink. Thus it can be seen that the more complete the fusion the better defined will be the zone, and the very fact that it is possible to ascertain the specific gravity of the zone ensures the rock having been converted into a perfectly-homogeneous glass. The change in specific gravity having been thus ascertained, the percentage-increase in volume of the rock on becoming glass can be calculated from the formula V = ™ V = — = ^i • 1 dx' 2 d2 d2 ' where d1 = Density of rock, d2 = Density of glass, Yl = 100, V2 = Volume of glass. The following list comprises some of the results ascertained by previous investigators. The numbers refer to percentage-increase in volume : — Delesse. Bischqf. Granite 9tollp.cent. | Granite 18*7 p. cent. Syenite 6 to 9 Granitoid porphyry . 8 to 10 Diorite 6 to 8 Melaphyres 6 Basalts 3 to 4 Glassy lavas 1 to 3 Basalt 7"4 Trachyte 8*5 Forbes. Bowley-Rag dolerite... 6*36 Carl Bams. Diabase 11 Nearly all the rocks experimented on come from well-known localities, and have been analysed ; references to these analyses are given at the end of this paper (p. 161). The melting of the powdered rocks was watched through coloured glasses, and their behaviour was found to vary only so far as their viscosity and coloration were concerned. The acid rocks were hard to fuse, and crushing and remelting had to be resorted to in several cases before a good zone could be obtained in the diffusion-column. The colours of the glasses varied from a black almost metallic appearance in the case of the gabbro, through stages of bottle- green and pale-green, to the perfectly-transparent rhyolite-glass. Unfused crystalline particles could often be seen in the molten glass, but these eventually disappeared after further heating. Bubbles seemed only to be formed at high temperatures ; these 150 MR. J. A. DOUGLAS ON CHANGES OF PHYSICAL [May I907, increased in size by coalition and rose to the surface, where they were expelled. In the acid rocks, however, owing to their greater viscosity, they were extremely difficult to drive off. The molten glasses, at temperatures well above their fusion- points, more especially the basic forms, had the appearance of boiling ; this, however, was not o£ long duration. The majority of the rocks examined were easily fused, giving clear glasses of a bottle-green colour, almost free from bubbles. The following cases, however, require special mention : — 1. Shap Granite. — A somewhat larger specimen of this rock was crushed up, owing to the presence of porphyritic orthoclase-crystals. It was very hard to fuse, and had to be crushed and remelted twice before a zone could be obtained. The glass was of a pale-green colour. 2. Peterhead Granite. — Fused with difficulty; was crushed and re- melted. For some time small brown specks remained undissolved, these being probably biotite. The glass was colourless, and gave one of the best-defined zones. 3. Eh yo lite. — Was very hard to fuse, containing many bubbles which were driven off with difficulty. Glass perfectly colourless and trans- parent. 4. Gabbro. — Very low fusion-point. Glass black and opaque, with an almost metallic lustre ; flooded the ribbon at high temperatures. 5. Quartz-Enstatite-Diabase. — Fused with difficulty, probably owing to the presence of quartz. The glass was crushed and remelted. In no case did there appear to be any action on the platinum- ribbon. I append (on p. 151) a tabulated list of the rocks that were experimented on, showing the change of specific gravity and per- centage-increase of volume on fusion. It will be seen that this increase attains a maximum in the acid plutonic rocks, and decreases with an increase of basicity. The presence of quartz in more basic rocks seems to affect readily the increase of volume ; this is very noticeable in the tonalite and quartz-enstatite-diabase, the latter having an expansion nearly as great as that of Shap granite. The three specimens of andesite resemble one another closely. These results, although slightly lower in many cases than those of Delesse, do not differ from them to any great extent. They merely serve to demonstrate, by an entirely- different method, the great expansion which must eventuate when an igneous rock becomes converted into the molten state. A considerable contraction takes place when a molten magma solidifies as glass, and this must be greatly increased if crystallization occurs. A comparison may, I think, be drawn between the conditions under which the enormous lava-flows of Iceland, India, and North America, known as ' fissure-eruptions,' were formed, with the con- ditions which may be obtained in a small platinum-furnace, such as the one used in the foregoing experiments. The behaviour of the gabbro may be taken as typical of the other basic rocks. It was found that, on placing a small portion of the powdered rock at the bottom of a U-shaped loop in the ribbon, and suddenly raising the temperature to a point many degrees above its fusion- point, an instantaneous melting took place, and so great was the "Vol. 63.~] CONSTANTS IN MINERALS AND IGNEOUS ROCKS. 151 expansion that the molten glass completely filled the loop and welled out, flooding the platinum-ribbon on each side. Name. Locality. Sp. Gr. of 1 Crystalline Rock. 1 'Granite Shap Fells (Cumber- land). Peterhead (Aberdeen) 2 | Granite 3 Sjrenite 4 iTonalite 5 iDiorite 6 IDiorite 7 Gabbro Plauen'scber Grand, Dresden. New Zealand Guernsey 8 JQuartz-enstatite - diabase. 9 tRhyolite Olivine-dolerite ... Dolerite Dolerite jWhin Sill.... New Zealand Markfield (Leicester, shire). Carrock Fell (Cum- berland). Penmaenmawr Tardree (Antrim) .. Clee Hills (Shrop- shire). Rowley Rag 13 ;Micropoecilitic 1 andesite. 14 jMicropcecilitic [New Zealand andesite. 15 Hyalopilitic an - New Zealand desite. 2-656 2-630 2-724 2-765 2-833 2-880 2-940 2-790 2-460 2-889 2-800 2-925 2-670 2*700 2-692 Sp. Gr. 1 Change of of Glass. Sp. Gr. 2-446 2-376 2-560 2-575 2-680 2*710 2-791 2-578 2375 2-775 2-640 2-800 2525 2-570 2-550 210 254 164 190 153 170 149 212 085 114 160 125 145 130 142 Percentage Increase in Volume. 8-58 10-69 6-40 7-37 5-70 6-27 5-41 8-20 3-50 4-14 6-06 4-46 5-74 5-05 5-56 If a mass of igneous rock be imagined in the earth's interior, kept solid by pressure, though far above its melting-point : on a sudden release of this pressure, by a dislocation along a fault or flaw-plane, the conditions would be analogous to the above, and an immense outpouring of lava might take place. The melting-points of the glasses formed by the fusion of the above rocks were taken by means of a meldometer, constructed after the model of that invented by Prof. Joly (6). The tempe- ratures are calculated from the observed expansion of a platinum- ribbon, previously calibrated with substances of known melting- points, which takes place when it is heated by an electric current. A description of this instrument, with its method of use, is given by Mr. E-. S. Cusack (2). The substances used in calibration of the ribbon were silver-chloride, potassium-bromide, potassium-carbonate, copper-oxide, and palladium. The current was the same as that used for the platinum-furnace, but it was brought down to a suitable strength by means of galvanized-iron wire resistance-coils. There was also an additional rheostat, in the form of two parallel German- silver wires connected by a sliding bridge : this had a total resist- 152 ME. J. A. DOUGLAS ON CHANGES OF PHYSICAL [May I907, ance equal to the difference between any two of the contact-studs on the large coils, and thus could be used in more detailed obser- vations. These wires were connected at one end to springs which prevented them from sagging when they became heated. The head of the micrometer-screw, used in measuring the expansion of the ribbon, could be read to -0005 of a millimetre. The platinum-ribbon was similar to that employed by Mr. Cusack (2), a length of about 10 centimetres being used for each experiment. When in use, it was surrounded by a trough of asbestos to exclude draughts ; a thin film of mica was also used as a cover, which in no way hindered the view of the microscope. The appearance of minute fragments of the glasses on the ribbon was not conducive to exact determinations of their melting-points ; a considerable range has therefore been recorded, the highest points being those at which the glass was undoubtedly molten, the lowest, those at which it seemed to become viscid. The variation in their melting-points is hardly as great as the difference in their composition would seem to suggest • however, it must be recog- nized that the melting-point of the glass must be considerably lower than that of the crystalline rock, and this difference may vary, as do the differences in specific gravity, with the composition of the rock. The following is a list of the melting-points of the rock-glasses, as determined by the meldometer : — Rhyolite 1260° C. Shap granite 1235-1255° C. Peterhead granite 1215° C. Plauen'scher syenite 1165-1175° C. Tonalite 1150° C. Markfield diorite 1147° 0. Guernsey diorite 1125°C. Quartz-diabase 1085-1105° C. Whin-Sill dolerite 1107° O. Eowley-Rag dolerite 1100° C. Andesite (14 on p. 151) 1095-1125° C. Andesite(13 do. ) 1095-1120°C. Andesite (15 do. ) 1097-1100° C. G-abbro 1085° C. Clee-Hills dolerite 1070° O. The refractive indices of the rock-glasses were determined by the microscopic method employed by Becker in the identification of the felspars. The nicol-prisms are removed, and a diaphragm put under the stage of the microscope ; then, on focussing down with a high-power objective, a halo of light is seen to pass from the substance of higher refractive index to that of the lower. Thus, if the glass be of higher refractive index than the fluid in which it is immersed, the halo will pass outwards. By immersion in a series of fluids of known refractive index, the refractive indices of the glasses may readily be determined ; the greater the number of fluids employed, the more exact will be the results. The fluids used in the determinations here recorded ranged by intervals of '0005 from aniline (1*588) down to copaiba balsam Vol. 63.^ CONSTANTS IN MINERALS AND IGNEOUS ROCKS. 153 (1-517). For better observations of the halo, it was found convenient to use light passed through a coloured medium, such as a solution of potassium-bichromate. The following list shows the comparison between the approximate refractive indices of the glasses, with their specific gravities : — Xame. Sp. Gr. of Glass. Befractive Index. 1 . Rhyolite 2*375 Slightly greater than 1 '527 2. Peterhead granite 2*376 Between 1 '527 and 1-533 3. Shap granite 2*446 Between 1*527 and 1 -533 4. Micropoecilitic andesite 2*525 About 1'567 5. Hyalopilitic andesite 2*550 Between 1*567 and 1*573 6. Syenite 2*560 „ 1*567 and 1*573 7. Micropoecilitic andesite 2*570 „ 1*567 and 1*573 8. Tonalite 2*575 „ 1*567 and 1-573 9. Penmaenmawr diabase 2*578 ,, 1*567 and 1*573 10. Rowley-Bag dolerite 2*640 „ 1*573 and 1*578 11. Guernsey diorite 2*680 „ 1*573 and 1*578 12. Markfield diorite 2*710 „ 1*573 and 1*578 13. Olee-Hills dolerite 2*775 Less than 1*578 14. Gabbro 2*791 Less than 1*578 15. Whin-Sill dolerite 2*800 About 1 *578 These results are merely approximate, owing to the wide inter- vals between the fluids ; they comply, however, with the formula n 1 — — =K, where d— Density, n~ Refractive index. Fusion of Minerals. The methods used in estimating the change of specific gravity which accompanied the fusion of the minerals examined were similar to those employed in dealing with the rocks. Certain members of the soda-lime felspar series were the first chosen to be experimented on, since they are generally recognized as consti- tuting the most interesting and important group of rock-forming minerals. Specimens were selected from known localities, the composition of which had been found by analysis to approximate most nearly to the theoretical composition. The method of procedure was as follows : — The mineral to be examined was crushed in a steel mortar, and passed through a fine copper sieve ; the powder thus obtained was placed in a beaker, and washed with distilled water in order to remove the impalpable dust. It was then carefully dried in a water-oven, and finally purified by means of a mineral- separator similar to that described by Prof. Sollas in Quart. Journ. Geol. Soc. vol. lviii (1902) p. 163. The fluids used were carbon-tetrachloride and methylene-iodide. It was found possible, with certain precautions, to separate components differing in specific gravity by two figures in the third place of decimals. The chief source of error in this type of apparatus is that due to evaporation round the stoppers. Since the separation will be more perfect the longer the time taken, and the more frequently the fluid is agitated, in dealing with so small a range of specific gra vitr- ei. J. G. S. No. 250. m 154 ME. J. A. DOUGLAS ON CHANGES OF PHYSICAL [May I907, it is absolutely necessary to prevent this evaporation. The following method was found effective : — A short length of broad rubber-tubing was passed over the head of the separator, so as to fit closely round the base of the neck, where it was secured by an elastic band. This formed a cup, which could be filled with mercury to above the level of the stopper. The lower limb of the separator, carrying the small stopper, was fitted into a wooden tube also filled with mercury. Thus evaporation from either end was completely prevented. The apparatus was swung from a horizontal wire, and the slight movement necessary for separation was obtained by passing one end of a string through the elastic band mentioned above, and causing the other end to be jerked at intervals by clockwork. The strength and periodicity of the jerks could be regulated by increasing or diminishing the length of the string. Thus, by causing the lower end of the separator to tap against a wooden upright, the fluid could be gently agitated for an indefinite period. The purified mineral, of known specific gravity, was removed from the separator, washed with benzol, and dried in a water oven ; it was then ground down to the finest powder in an agate mortar, and melted in the platinum-furnace, as described above. The specific gravity of the homogeneous glass thus formed was measured in a diffusion-column, and the percentage -increase in volume calculated. The following list gives the result of these determinations, and it will be seen that the increase of volume becomes gradually less in passing from the soda- to the lime-end of the series. This, however, is to be expected from a study of the change of volume in the igneous rocks. The Roman numerals refer to analyses in Prof. Carl Hintze's * Handbuch der Mineralogie ' vol. ii (1897) pp. 1470, 1492, 1531, & 1549. Sj). Gr. Sp. Gr. Chavge Percentage of of of increase Crystal. Glass. Sp. Gr. of volume. XXV. Albite (Pfitschthal, Tyrol)... 2625 2-373 -252 10*61 LXXXVI. 01igoelase(Tvede- I 2.Q5Q 2.m ,m ^ st-Vcind ) •.«••.••••••... J Andesine (separated 1 ^ ^^ .^ from tonahte) J CLI-OLXII.^Labradorite(Lab-j 2.m 2^Q ,m 5.gg XIX-XXL Ancr^ite (Monte j ^-^ 2mb .^ ^ The following minerals were also experimented on : — CXLIV. Adularia(St.Gotthard).. 2'575 2-370 '205 8-65 Leucite (Vesuvian lava).. 2-480 2-410 '070 2-90 Apatite (St. Gotthard)... 3-197 2-972 -225 7'57 Tremolite 2*990 2-780 '210 7"55 Actinolite 3'040 2-810 '230 8*18 Pargasite 3'109 2'790 '319 1P43 Quartz, infusible. Andalusite is not fusible in sufficient quantities to obtain a zone of glass. Vol. 6$.~] CONSTANTS IN MINEKALS AND IGNEOUS EOCKS, 155 These mineral-glasses were all colourless and transparent, with the exception of pargasite which was pale-yellow, and aetinolite which was olive-green ; they all, with the exception of apatite, have well-defined zones in the different columns. The melting-points of the felspar-glasses were ascertained by means of the meldometer. The results obtained seemed at first far from satisfactory, since they appeared to have no relation to those found by Prof. Joly, Mr. Cusack, or Prof. Dcelter, even allowing for difference in purity of the specimens melted, and errors of experi- ment. They were, however, found to lie on a regular curve, and repeated trials still gave the same high temperatures. Some time after obtaining these results, my attention was drawn to a paper by Messrs. Day & Allen, published in the American Journal of Science (3). This paper gives an account of the thermal properties of the felspars, the melting-points of which were found to be considerably higher than any previously obtained. A distinct comparison can be drawn between my results and those recorded in Messrs. Day & Allen's paper, although the former were determined independently and by a different method. The method employed by Day & Allen may be briefly described as follows : — Chemically-pure soda-lime felspars were prepared synthetically; these were powdered, and then placed in platinum- crucibles of 100 cubic-centimetre capacity, which were slowly heated to above 1400° C. in an electric furnace. The temperatures up to 1150° were taken with a gas-thermo- meter ; above this point they were extrapolated by means of the thermo-electric force developed on heating a thermo-element com- posed of pure platinum and platinum with 10 per cent, of rhodium, a curve was plotted showing the relation between time and tempera- ture, and the position of an abrupt change in the form of the curve, which denoted an absorption of latent heat, was taken to represent the temperature at which fusion commenced. The melting-points were, by this method, found to lie on a straight line, which showed a gradual fall of temperature towards the albite- end of the series. The soda-lime felspars, then, since they comply with Dr. Fr. "W. Kiister's rule that ' the solidifying point of an isomorphous mixture lies on a straight line joining the melting-points of the components, and can be calculated from the percentage- composition of the mixture' (see also Zeitschr. fur Physikalische Chemie, vol.viii,1891,p. 577). may be considered as isomorphous mixtures of pure albite with pure anorthite, which correspond to Type I of Bakhuis Roozeboonrs theoretical curves for those substances which mix in all proportions. In the accompanying diagram (fig. 2, p. 156), wherein the ordi- nate^ represent the temperatures at which fusion takes place, and the abscissae the specific gravities of the crystalline substances, the upper curve shows the relation between the two, found by Messrs. Day & Allen with artificial felspars by the thermo-electric method, and the lower dotted curve the relation found by means m 2 I Tem Q pera a ture © 01 o 1 m \ 5 i iy \ < < • \ % *v V \ V \ \ < \ \ ^abrade B > S3 .5 0) -3 \ \ 1 \ » S3 » DC \ i Fig. 2 . Curves showing relation between Specific Gravity of Crystal and the melting-paints of A - Crystal, B - Glass. A \H \ 1 1 t 1 \feg \ ^5 x \ ■* J j \ 3 Vol. 63.~] CHANGES OF PHYSICAL CONSTANTS IN MINERALS, ETC. 157 of the meldometer when using purified natural felspars. This dotted curve represents the fusion-point of the glasses formed by melting crystals of the given specific gravities : therefore, it is necessarily lower than one obtained for the crystalline substances themselves. I can in no way account for the wide difference between my results and those of Prof. Joly & Mr. Cusack ; the purification of the tminerals could hardly have so great an effect. In using the meldometer, I found it absolutely necessary to calibrate each ribbon separately. When this was done, I found that no two curves corresponded exactly; and readings from one ribbon, if inserted on the curve obtained for another, gave results differing widely from those obtained on its true curve. The melting-points that I have given are those at which the particle appears completely molten, and change of form begins to take place. The following tabulated list shows the similarity between the change of specific gravities of the natural and of the artificial felspars, and a comparison of melting-points : — Sp. Gr. Sp. Gr. Melting-point Melting-point of crystal. of glass. of crystal. of glass. *2-765 2-700 1532° C. 2-750 2-665 1505° C. *2733 2-648 1500° O. *2-710 2-590 1463° C. 2-700 2-550 1390° C. *2-679 2-533 14i9° C. 2-677 2-514 1340° C. *2-660 2-487 1367° C. 1 2656 2-470 1310° C. *2-649 2-458 1340° C. 2-625 2-373 1268° C. *2-605 2-382 Those marked with an asterisk are the chemically-synthesized felspars of Messrs. Day & Allen. The greatest difficulty met with in using this type of instru- ment is that due to the viscosity of the substances examined, since there appears to the eye to be no abrupt change between the crystal immediately before f ision and the fused substance when in a viscous state. This is especially the case in minerals which undergo a long period of viscosity such as albite ; and in such minerals deorientation may be withheld for some time, owing to their high viscosity.1 1 For a criticism of the two methods of determining melting-points men- tioned in this paper, see C. Dcelter (5, iii) and A. L. Day & E. S. Shepherd (3 ). 158 MR. J. A. DOUGLAS ON CHANGES OP PHYSICAL [May I907, Eutectic Mixtures.1 The relation which undoubtedly exists between saline solutions and igneous 0 magmas is one that bears strongly on all problems of petrology. Akerman 2, experimenting with silicate-slags similar in composition to igneous rocks, has demonstrated that mixtures of two given minerals show a distinct lowering of the melting-point, the greatest lowering taking place when they are mixed in eutectic proportions. This phenomenon is analogous to that observed in a saline solution, such as a mixture of salt and water. In 1888, in his ' British Petrography,' pp. 401-402, Dr. Teall suggested that a micropegmatitic intergrowth of quartz and felspar probably represented an eutectic mixture, being the last product of consolidation in the rock-magma. 0 In dry melts, such as those obtained by Akerman, certain minerals are typically absent ; these include quartz and orthoclase- felspar. The eutectic proportions of these minerals cannot, then, be determined by cooling a molten rock or silicate-slag in the laboratory. The only method that appears possible is to deter- mine the melting-points of certain mixtures of the two minerals, and by this means endeavour to find the eutectic mixture, that is, the one with the lowest melting-point. From the careful analyses of pegmatites from various localities, which have been made by Dr. Teall, Prof. Vogt, and Prof. Lagorio, the eutectic proportions have been calculated to be about 70 per cent, of felspar with 30 per cent, of quartz. These proportions have apparently never been determined experimentally, although some years ago Prof. Joly 3 ascertained that the melting-point of micropegmatite was slightly lower than that of orthoclase. The following is a brief account of an attempt to find experiment- ally the eutectic proportions of quartz and orthoclase by determining the melting-points of glasses corresponding in composition with the formulas OrQ,6, OrQ,3, 0rQ2 (eutectic), Or2Q3. These glasses were obtained by fusing carefully-weighed proportions of chemically-pure artificially-prepared silica and purified orthoclase in the platinum- furnace. The eutectic proportion, so far as could be observed, showed no lowering of the fusion-point ; in fact, there was a gradual rise in temperature with the increase in the percentage of silica, showing a certain resemblance to Type IV of Bakhuis Koozeboom (8). This result cannot, however, be taken as a proof telling against the eutectic hypothesis, since the viscosity of the glasses is of so high an order of magnitude that it is practically impossible, with the comparatively-rapid heating necessary when using the meldometer, to determine accurately the point at which melting commences. 1 An excellent summary of recent work on the subject of eutectics is given by Prof. H. A. Miers, in his Presidential Address to the Geological Section of the British Association, at the Meeting in South Africa, 'Nature' vol. lxxii (Aug. 24th, 1905) pp. 408 et segg. 2 'Die zum Schmelzen von Schlacken erforderlichen Warmemengen ' Iern- kontorets Annaler, 1886 ; also in ' Stahl & Eisen ' 1886. 3 See J. J. H. Teall, Quart. Journ. Geol. Soc. vol. lvii (1901) p. lxxvi. Vol. 6$.'] CONSTANTS IN MINERALS AND IGNEOUS ROCKS. 159 Moreover, the conditions under which a pegmatite must have consolidated are entirely different from those obtainable in the laboratory. Here, then, the analogy with a saline solution fails. In the cooling-down of a magma, the final consolidation of which gives rise to less than 70 per cent, of orthoclase, the quartz ought, according to the eutectic hypothesis, to be the first to solidify, and no orthoclase should crystallize until the composition of the magma has reached eutectic proportions. In the granites, however, the orthoclase is found to have crystallized before the quartz. This must, in great part, be due to the extreme viscosity of the latter and to supercooling of the magma, combined with the better crystallizing properties of orthoclase. Viscosity is, therefore, the great drawback in determining melting-points by the method of direct observation. If it were possible to heat the glasses very gradually over a long period of time, the eutectic mixture might be seen to melt more readily than the others. This, owing to the heating of the resistance-wires and consequent diminution of the current, and also owing to the injurious effect which long observations of the ribbon have on the eyesight, is hardly possible with the meldometer. The thermo-electric method, by which Messrs. Day & Shepherd have recently determined the eutectic proportions of the lime-silica series, is, I imagine, more likely to give satisfactory results. Prof. Dcelter (5), however, experimenting on mixtures of minerals, has found that the melting-points of the mixtures are intermediate between the melting-points of the constituents, and concludes that there is no evidence that the eutectic hypothesis can be applied to molten silicates. The same fact is shown by the results obtained with the meldometer, namely : — Melting-point of OrQ6 1317° 0. OrQ3 1292° C. OrQ2 1285° 0. .. Or2Q3 1265° 0. Or-glass 1220° C. On the other hand, a mixture of orthoclase aud albite, in the pro- portions of 40 per cent, orthoclase to 60 per cent, albite (which, from analyses of cryptoperthites, has been determined as their ' eutectic mixture '), when fused into a glass and its melting-point compared with those of albite- and orthoclase-glasses, yielded the following results : — Melting-point of albite-glass 1268° 0. „ ,, orthoclase-glass 1220° C. „ ,, cryptoperthite-glass . 1175° C. In this case, then, there seems to be a distinct lowering of the melting-point and a correspondence to the fifth curve of Bakhuis Eoozeboom (8). Since the conditions which govern the production of eutectic mixtures in igneous magmas are so little known, it would appear that the construction of apparatus by which a nearer approach to plutonic conditions may be attained must be attempted before any definite result can be achieved experimentally. 160 MR. J. A. DOUGLAS ON CHANGES OF PHYSICAL [May 1907, •" In conclusion, I must thank Prof. Sollas for his kind supervision and advice in the course of the preparation of this paper. Since writing the above, I have received a paper by A. Bygden : { Ueber das quantitative Yerhaltniss zwischen Feldspath & Quarz in Schriftgraniten ' Bull. Geol. Inst. Univ. Upsala, vol. vii, 1904-05 (1906) pp. 1-18 : this paper, after giving a short outline of Prof. Yogt's theoretical conclusions on graphic granites, proceeds with an account of analyses of various pegmatites, the results of which seem to show that these rocks may vary considerably in the pro- portion of felspar and quartz which they contain, ranging from 81*71 per cent, of felspar and 18*29 per cent, of quartz to 62*07 per cent, of felspar and 37*93 per cent, of quartz, or in molecular proportions from 1 : 1 to 1 : 2*71. The specific gravities of the rocks analysed — which were taken by two methods, namely, (1) weighing in air and water, (2) by the use of a ' Westphal balance ' employing mixtures of bromoform and benzol as heavy fluids — seem hardly to corre- spond to the mineral composition. For example, two specimens of specific gravity 2*58 were found by analysis to have the com- positions 1 of felspar to 1*2 of quartz, and 1 of felspar to 2*36 of quartz. If, then, pegmatites be found to vary so much in com- position, the production of eutectic mixtures must be controlled by some, at present, unknown agency. From the presence of water included in cavities in the quartz, and the analogy of the silica- hydrates, it would appear that water was a dominant factor. Bibliographical List. 1. Bakus, C. ' The Fusion-Constants of Igneous Rock ' pt. ii, Phil. Mag. ser. 5, vol. xxxv (1893) p. 189. 2. Cusack, R. S. ' On the Melting- Points of Minerals ' Proc. Roy. Irish Acad. ser. 3, vol. iv (1896-98) p. 399. 3. Day, A. L., & Allen, E. T. ' The Isomorphism & Thermal Properties of the Felspars' Amer. Journ. Sci. ser. 4, vol. xix (1905) pp. 93-142. See also ' High-Temperature Research on the Felspars,' in ' Nature ' vol. lxxii (1905) pp. 258-59. Day, A. L., & Shepherd, E. S. 'The Lime-Silica Series of Minerals' Amer. Journ. Sci. ser. 4, vol. xxii (1906) p. 265. See also ' Nature ' vol. lxxv (1906) p. 112. 4. Delesse, A. ' Recherches sur les Verres provenant de la Fusion des Roches ' Bull. Soc. Geol. France, ser. 2, vol. iv (1847) p. 1380. 5. DcELTER, C. (i) ' Ueher die Silikatschmelzlosungen ' Centralblatt f. Min. 1905, pp. 144-47. (ii) 'Ueher die Bestimmung der Schmelzpunkte bei Mineralien & Ge- steinen' Tscherm. Min. & Petr. Mitth. vol. xx (1901) p. 210; 'Neue Bestimmungen von Schmelzpunkten ' ibid. vol. xxi (1902) p. 23; ' Beziehungen zwischen Schmelzpunkt & chemischer Zusammensetzung der Mineralien ' ibid. vol. xxii (1903) p. 297. (iii) 'Die Untersuchungsmethoden bei Silikatschmelzen ' Sitzungsber. d. k. Akad. Wissensch. Wien, vol. cxv (1906) p. 617. 6. Joly, J. ' On the Determination of the Melting-Points of Minerals ' Proc. Roy. Irish Acad. ser. 3, vol. ii (1891-93) p. 38. - 7. Lane, A. C. ' The Role of Possible Eutectics in Rock-Magmas' Journ. Geol. Chicago, vol. xii (1904) pp. 89-93. 8. Roozeeoom, H. W. B. ' Erstarrungspunkte der Mischkrystalle zweier Stoffe ' Zeitschr. f. Physikalische Chemie, vol. xxx (1899) p. 385. 9. Roth, J. ' Die plutonischen Gesteine ; Specifisches Gewicht & Schmelz- versuche ' Allgemeine & Chemische Geologie, vol. ii (1883-87) p. 51. Vol. 6$.~] CONSTANTS IN MINERALS AND IGNEOUS ROCKS. 161 10. Soxlas, W. J. ' A Process for the Mineral-Analysis of Rocks ' Quart. Journ. Geol. Soc. vol. lviii (1902) pp. 163-76. 11. Teall, J. J. H. 'British Petrograplvy ' 1888, chapt. xiii ; and 'Presidential Address' Quart. Journ. Geol. Soc. vol. lvii (1901) pp. lxx et seqq. 12. Vogt, J. H. L. (i) ' Die Silikatschmelzlosungen ' Vidensk. Selsk. Skrifter, No. 8 (1903) pt. i. (ii) ' Physikalisch-Chemische Gesetze dei1 Krystallisationsfolge in Eruptiv- gesteinen ' Tscherm. Min. & Petr. Mitth. vol. xxiv (1905) p. 437. Rock-analyses (references) : — (i) Quart. Journ. Geol. Soc. vol. xlvii (1891) p. 276; (ii) J. Peestwich, 'Geology' vol. i (1886) p. 41; (iii, iv) W. J. Solias, Quart. Journ. Geol. Soc. vol. lviii (1902) pp. 163-76 ; (v-xii) F. H. Hatch, ' Textbook of Petrology ' 2nd ed. (1892). Discussion. The Chairman (Dr. A. Strahan) commented on the skill with which these difficult experiments had heen carried out. The increase in volume undergone by some of the rocks on passing into the glassy condition came to him as a surprise. Mr. J. Y. Elsden called attention to the Author's determination of the melting-points of various glasses. He believed that it was generally admitted that, from a physical point of view, glasses had no definite melting-point. They behaved as liquids of high viscosity. He would suggest, therefore, that the Author's figures represented, not melting-points, but rather the relative rates of diminution of viscosity. Prof. "W. W. Watts congratulated the Society on being the recipient of an exceedingly-important contribution to experimental geology. He called especial attention to the Author's results with regard to the expansion of certain acid rocks, which expanded as much as 10 per cent, in passing into the glassy condition. The still greater expansion in liquefying would provide an explanation of the enormous force developed in volcanic eruptions. Prof. Sollas remarked that the extreme lucidity with which the Author had communicated his results fittingly corresponded with the precision which marked his work as an experimenter. The specific gravity of a rock afforded a most important indication as to its nature ; but hitherto full advantage could not be taken of this, owing to the fact that rocks were not all in the same physical state, some being glassy, some crystalline, and some both crystalline and glassy. To render specific gravity a test of general application, all rocks must be reduced to a common state ; and, since a universal crystalline state was not attainable, recourse must be had to the glassy. The Author's method furnished a simple and accurate means of accomplishing this, and should prove of great practical value, especially in determining the affinities of volcanic rocks. For this reason the reinstatement of Prof. Joly's meldometer as an instru- ment of precise research was especially welcome. The results of the Author, and those obtained by Messrs. Day & Allen with much more expensive apparatus, were in mutual confirmation. The Author thanked the Fellows for their kind reception of his paper. 162 ME. G. W. LAMPLTJGH ON THE [^lay I907, 12. The Geology of the Zambezi Basin around the Batoka Goege (Rhodesia). By Geoege William Lampltjgh, F.R.S., F.G.S. With Peteogeaphical Notes by Heebeet Hexey Thomas, M. A., B.Sc, F.G.S. (Read January 23rd, 1907.) [Plates X-XVIL] Contents. Page I. Introduction 162 II. Previous Literature 163 III. Physical Features 165 IV. Geological Structure 171 (1 ) The Fundamental Complex 171 (2) TheWankie Sandstones and Coal-measures. 173 (3) The Batoka Basalts 182 (4) The Flaggy Sandstone of Boomka, etc. ... 196 (5) The Superficial Deposits 198 V. Summary and Conclusion 206 Appendix I. Petrographical Notes, by H. H. Thomas 207 II. Local Notes on the Batoka Basalts 212 III. Local Notes on the Superficial Deposits 213 I. Inteoltjction. At the request of the Council of the British Association, I undertook to examine the country in the neighbourhood of the Victoria Falls of the Zambezi l River before the meeting of the Association in South Africa in the summer of 1905. Through the helpful co-operation of the British South Africa Company and the aid afforded to me by its officers in Rhodesia, I was enabled to make good use of the short time available to me for the task ; and by rapid traverses of the wild country eastward of the Falls I gleaned much information regarding the geology and physiography of this little-known region. A preliminary account of the exploration was presented at the meeting of the British Association in Johannesburg, and has since been published in the ; Report ' of that body.2 In this account the objects of the exploration and the circumstances of the journey are stated, and therefore need not be repeated here ; but of the geological results it was only possible at that time to give a bare outline, pending the further examination of the material collected. My present object is to deal more adequately with the geological evidence. The traverses occupied seven weeks in July and August, 1905, during which time a distance of over 600 miles was covered, partly on the northern and partly on the southern side of the Zambezi, as shown on the sketch-map (PI. XVII), the area embraced within 1 This spelling is adopted to conform with the usage of the Royal Geogra- phical Society, although personally I think that Livingstone's spelling Zambesi should have been retained. 2 Rep. Brit. Assoc. 1905 (South Africa) [London, 1906] pp. 292-301. Vol. 6^.~] GEOLOGY OF THE ZAMBEZI BASIN. 163 these traverses being over 2000 square miles. In exploration of this kind, through dime alt country, where the exigencies of the daily march are ever insistent, it is of course rarely practicable to follow up the evidence that presents itself. One must usually be content to snatch just so much as lies in one's path ; therefore it is inevitable that the facts which come under observation will frequently be of less consequence than those which remain undiscovered. In my attempt in the following pages to give coherence to the collected data, I am aware that some of the conclusions rest upon an imper- fect basis ; but it may be long before fuller knowledge is accumulated, and meanwhile it seems desirable that what we already possess be used so far as may be in temporarily bridging the gaps. The most serious difficulty in work of this kind arises from the absence of a topographical map upon which to record the geological observations. In the present case, some parts of our route appear not to have been previously traversed by the white man, while for the other parts the existing maps are too inaccurate to be of much service ; and I unfortunately found it impossible, under the conditions of our journey, to construct a map adequate to supply the deficiency. In plotting the imperfect sketch-map that accom- panies this paper, I have had to rely largely upon compass-bearings and dead reckoning, taking as a basis the plan of the railway. The country which I personally examined, and shall now more particularly describe, extends from near the Victoria Palls east- ward for about 75 miles to the confluence of the Zambezi with its tributary the Deka, and from the plateau north of the Zambezi southward for about 70 miles to the head- waters of the Deka. II. Peevious Literatuee. Until recently our knowledge of the geology of this part of Rhodesia depended upon the casual notes of a few travellers, of whom David Livingstone was first and foremost. In his eastward march from the Victoria Palls in 1855, and in his later journeys of 1860, Livingstone went to the northward of the country now to be described ; but at one place he turned southward to visit the great Moamba [Mamba] cataracts of the Zambezi within its gorge ; and at this spot only did our expedition touch the track of the great explorer. His record of these journeys includes some notes on the rocks of the Batoka Highlands,1 which are still, so far as I am aware, the only published information on the geology of that district (see p. 171). The best account, even to the present day, of the more frequently traversed country south of the Zambezi is that given by James Chapman in 1868. Though not pretending to technical knowledge, Chapman had an observant eye for the rocks ; and much geological 1 ' Missionary Travels & Researches in South Africa ' (London, 1857) chap, xxvi, p. 534 & chap, xxvii, pp. 542-43 ; and ' Narrative of an Expedition to the Zambesi & its Tributaries' (London, 1865) chap, xi, pp. 222-23. 164 ME. G. W. LAMPLUGH ON THE [May I907, information may be gleaned from his descriptions.1 The writings of the numerous later travellers who have recorded their journeyiugs through this part of the country contain no material addition to our knowledge of its structure.2 With the beginning of a technical literature within the last few years, the geology of the whole region has been placed on a firmer basis. In a paper contributed to this Society in 1903,3 Mr. A. J. C. Molyneux, F.G.S., described the sedimentary rocks of a broad strip of country south of the Zambezi, nearly conterminous with the eastern margin of the tract with which I have to deal, and evidently related to it in structure. In a later paper 4 Mr. Molyneux discussed the geological and physiographical features of the Yictoria Falls, and showed that the singular chasm into which the Zambezi plunges at this spot has been developed by normal erosion, and not, as popularly supposed, by a sudden rending of the earth's crust.5 In this paper the term ' Batoka Basalt ' is introduced for the basic lavas that form the country -rock around the Falls. 1 'Travels in the Interior of South Africa' vol. ii (London, 1868) chaps. iv-xi, pp. 83-278. 2 Some scraps may be gleaned from the following : — ' Explorations in South- West Africa ' by Thomas Baines (London, 1864) ; ' To the Yictoria Falls of the Zambesi ' by Eduard Mohr (Engl, transl. by N. D'Anvers, London, 1876) ; ' Seven Years in South Africa : Travels, Researches, & Hunting Adventures etc' by Emil Holub (Engl, transl. by E. E. Frewer, London, 1881, two vols.); 'How I crossed Africa' by Major Serpa Pinto (Engl, transl. by A. Elwes, London, 1881, two vols.); 'A Hunter's Wanderings in Africa 'by F. C. Selous (London, 1890) ; 'The New Africa' by Aurel Schulz & August Hammar (London, 1897) ; and later works by Major A. St. H. Gibbons and by Col. C. Harding, to which reference will be made in the context. 3 ' The Sedimentary Deposits of Southern Ehodesia ' Quart. Journ. Geol. Soc. vol. lix (1903) pp. 266-90. 4 'The Physical History of the Yictoria Falls' Geogr. Journ. vol. xxv (1905) pp. 40-55. 5 Although this idea of Livingstone's was repeated by all later travellers and had obtained general currency, it must be remembered that so long ago as 1865, Sir Archibald Geikie, now our President, had already recognized the real character of the Batoka Gorge. In the first edition of his 'Scenery of Scotland ' (Macmillan, 1865), after pointing out that in countries where the rainfall is small and frosts trifling or unknown, the rivers will cut perpendicular chasms of great depth, he remarks : — ' Thus the Zambesi in plunging over the precipice at the Yictoria Falls enters a gorge 100 feet deep [the depth originally assigned to it by Livingstone] and only 80 feet broad, which runs in a zigzag course for many miles. The river seems to have cut its way backward through this winding ravine until, owing to some subterranean movement, effecting a change of level, or to some other cause which would probably be detected by a geologist on the spot, the body of water in place of entering at the top of the ravine has been emptied over one of its sides ' (p. 33). And in a footnote on the same page, referring to his examination of the model of the Yictoria Falls (now in the possession of the Boyal Geo- graphical Society) which had been prepared from Livingstone's description, our President adds ' In looking at it I was much struck with the re- semblance of the so-called "gigantic fissure" to a ravine cut by the action of a stream where springs, rains, and frosts have played only a subordinate part.' The foregoing passages were written when Livingstone's great discovery of the Falls was still novel ; they were not reprinted in the later editions of the book, probably because, after the first flush of interest in the Falls had passed, it was felt that this reference to them was not well placed in a description of Scotland. Vol. 6^."] GEOLOGY OF THE ZAMBEZI BASIN. 165 An excellent report on the geology of Southern Rhodesia 1 by Mr. F. P. Mennell, F.G.S., published in 1904, deals more especially with the country around Bulawayo, which is illustrated by a geological map ; but it also contains a general sketch of a much wider region, and includes some references to the rocks in the area now under description. In this report, and in an earlier paper,2 Mr. Mennell records the petrographical characters of the Batoka Basalts and of other Rhodesian rocks. The ' Proceedings of the Rhodesian Scientific Association ' (Bulawayo : vols, i-v, 1899-1905) contain some further information respecting Khodesian rocks, though not directly referring to the tract within my traverses. In 1904 was published the important work of Dr. S. Passarge, entitled ' Die Kalahari,' 3 in which all the available data regarding the great interior basin of Central South Africa are summarized and discussed. In the light of his extensive personal researches in the Kalahari desert between the years 1896 and 1898 while acting as mining expert to the British West Charterland Company, Dr. Passarge skilfully brings together the scanty material contained in the records of previous travellers, and evolves an admirable interpretation of the geological structure and physiographical development of the whole basin. Although his bold generalizations frequently rest upon slender evidence, and are likely to require much modification, this remarkable work enables us to grasp the essential elements and probable significance of the structure of this vast territory. Dis- regarding the usual geographical limitations of the term, lie includes within ' the Kalahari ' the whole region wherein ' half- steppe ' or * semi- arid ' conditions prevail. Thus, Barotseland and a wide contiguous tract north of the Zambezi are entitled by him the 4 Northern Kalahari ' ; and his ' Middle Kalahari ' embraces a great belt of country south of the Zambezi, extending from the inner margin of Matabeleland to the western watershed of the continent. The country which I traversed falls therefore within this latter division ; and its geological structure is described, and in part represented on a geological map, based mainly on the accounts given by Chapman and Livingstone. I shall have occasion frequently to revert to Dr. Passarge's work in the context. III. Physical Features. Though complex in detail, the broader features of the region under examination are simple. Above the Victoria Falls, the Zambezi is a wide placid river flowing at an elevation of about 1 ' The Geology of Southern Rhodesia ' Special Report No. 2, Rhodesia Museum (Bulawayo, 1904) pp. 42, with geological map. 2 'Contributions to South African Petrography' Geol. Mag. dec. 4, vol. ix (1902) pp. 356-66 (description of basalt from Victoria Falls and Deka, with figure, p. 358). 3 ' Die Kalahari, Versuch einer physisch-geographischen Darstellung der Sandfelder des siidafrikanischen Beckens ' Berlin, 1904, pp. 822 & Kartenband. 166 ME. <*. W. LAMPLTJGH OS THE [May I907, 3000 feet above sea-level in a shallow valley through a country of low relief. This country forms part of the great interior basin of South Africa, whose featureless plains extend far to the northward, westward, and southward ; ranging through some 20 degrees of latitude, from beyond the watershed of the Congo nearly to the Orange River ; and through 8 or 10 degrees of longitude, from the rim of the west-coast slope to the valley of the Limpopo. Except around a few clustered ' island-hills ' (Insel-bergen) the drainage- gradients throughout this great basin are peculiarly low, and the river-channels are only very slightly incised and present many abnormalities. Dr. Passarge gives strong reason for believing that the development of this plain has been due to prolonged and re- current desert-conditions. That there have been important changes of condition as regards rainfall and surface -drainage during and since the development of the plain is evident, as Livingstone and later travellers have recognized, from the character of the superficial deposits ; the latest change in this, as in many other parts of the world, having been one of progressive desiccation. Prom his investigation of these deposits Dr. Passarge considers that at some time previous to the setting-in of the recent desiccation, there was a period of exceptional humidity in the region, probably contemporaneous with the Glacial Epoch of higher latitudes, during which the plain was watered by many rivers and lakes that have now disappeared. But before this humid period there was, he believes, a time of arid conditions ; and he interprets the evidence as indicating also earlier cycles of alternation. Whatever its origin, this high-lying basin-plain, for the most part deeply sand-covered, with its anomalous drainage-system, constitutes the most striking feature in the physiographic structure of Southern Africa. At the Victoria Falls, however, the broad Zambezi drops in a single plunge from this region of low relief ; and .narrowing into a deep and powerful torrent, hurries impetuously towards the Indian Ocean. That a large volume of the drainage from the interior must long have held this course is proved, as Mr. Molyneux has pointed out, by the length and character of the trough which has been excavated; the distance from the Falls to the lowermost of the great gorges which these inland waters have carved out in crossing the high eastern rim of the continent being nearly 600 miles, besides the further 350 miles of low country that is traversed by the river before it reaches the ocean. The antiquity of the interior plateau denoted by this great drainage-channel is indeed significant. The country with which I have now to deal lies around the highest of the gorges — the Batoka Gorge, as I have proposed to name it. The strange zigzagging chasm just below the Victoria Falls, into whose astonishingly narrow gullet the waters of the Zambezi are gathered after their shattering plunge, has been frequently described. In tracing the river eastward we found that the gorge maintained its trench-like character for about 60 miles, Yol. 6^."] GEOLOGY OF THE ZAMBEZI BASIN. 167 and then rather suddenly expanded into a more open valley. The geological structure of the country remained unchanged, however, up to Makwa l or Wankie's Drift, the eastward limit of our journey along the Zambezi, several miles below the termination of the gorge ; where we were still on the same plateau-basalts which we had traced uninterruptedly from the Falls. Through its great trench the river pours tumultuously, like an overgrown mountain- torrent, fretted at short intervals into foaming rapids, and at the season of low water in places confined within rock-bound gullies sometimes not more than 20 or 30 yards in width ; but in such places bordered by wide platforms of bare rock, deeply indented with ' pot-holes,' over which the enormously augmented stream is poured in flood-time. The difference between the volume of the river during low water and during the floods must indeed be great ; since we saw indications, where the bottom of the gorge was narrow, that the river rises at least 50 feet above its dry-season level. It is to the effect of this extreme seasonal variation upon certain structural peculiarities of the basalts, presently to be described, that the characteristically acute swerves of the river within its gorge are to be attributed. The Zambezi at the Victoria Falls loses at once 360 feet of altitude, but this is only the first great step in its rapid descent; for, by the time that it reaches Makwa, after its emergence from the Batoka Gorge, it appears to have lost at least a further 800 or 900 feet.2 And although the basaltic plateau itself declines eastward, the river falls more rapidly in this direction ; so that the depth of the canon is increased from about 400 feet near its beginning to about 800 feet (by aneroid measurement) at the spot where I descended into it a few miles above its termination. As I have else- where discussed the indubitable evidence for the gradual develop- ment of the Gorge by erosion, it is needless for me to recapitulate the points. The photographs reproduced in Plates X-XIV, selected to show the features of the canon at different parts of its course, will also suffice to illustrate one of these points, to wit, the progressive reduction eastward in the steepness of its sides, from verticality in the newly-cut portion at the Falls to slopes of 30° or under in the older portion which has suffered prolonged weathering. 1 I have found that so much confusion arises from the repetition of Wankie or Wankies as a place-name in the district formerly ruled by the chief, Wankie or Tzwanki, that I propose hereafter to restrict the use of the name to the place where the coal-mine, railway-station and post-office are established, and to adopt Major A. St. H. Gibbons's term, Makwa, for Wankie's Drift or Ferry across the Zambezi. The old chief was much harried by the Matabeli, and had several times to shift the site of his settlement, so that there are still three or four places bearing his name. The nomenclature of the country, however, at present stands in need of revision in many particulars. 2 This estimate is based on my aneroid observations ; it is borne out by the figures given by Mohr (' To the Victoria Falls of the Zambesi ' 1876, p/329) for the height above sea-level of Wankie's village [Makwa] — 1680 feet ; and by Baines for the level, of his camp at Logier Hill — 1550 feet (' The Gold Eegions of South-Eastern Africa ' London, 1877, p. 187). 168 ME. G. W. LAMPLTTGH ON THE [May I907, Another result of the slow recession of the gorge is evident in the relation of the tributaries to the main river. On the north, these feeders radiate from the Batoka Upland, while on the south they mostly hold a north-easterly course at a low angle to that of the Zambezi. Above the Palls, the tributaries flow to the Zambezi in channels sunk very slightly below the general level of the plateau and make their confluence in open estuary-like inlets ; but below the Palls they are precipitated, before reaching the main river, into gloomy chasms that lead into the Batoka Gorge ; and these become longer in proportion to their increasing distance from the Palls. Thus the country bordering the main gorge is slashed by pre- cipitous ravines that stretch back farther and farther into the plateau as we go eastward, so that a great wedge of exceedingly broken country, very difficult to traverse, has been produced, expanding eastward on both sides of the river from its apex at the Palls. Where the influence of the rejuvenated drainage has been longest established, certain of the larger tributary rivers, as for example the Matetsi and the Deka, have likewise had time to widen out the lower reaches of their valleys, but all sooner or later entrench themselves within precipitous canons when traced back towards the plateau. The same rule appears to apply also far to the eastward of the country examined. Thus the Kafue Biver, a great tributary which joins the Zambezi from the north some 220 miles below the mouth of the Deka, is described as having a comparatively sluggish and navigable course for 20 miles back from its confluence ; but at the head of this low- level stretch the river tumbles in a succession of foaming cataracts for 2 miles through a rugged gorge which leads up to the high plateau ; and before reaching this sharp descent, in which it loses over 1000 feet of altitude,1 the stream has flowed placidly in a broad shallow channel over the undulating plateau for several hundred miles. This tearing-down of the high plains at their edges and the gradual lengthening of the low-level channels is the ruling factor in the physiographical development of the Zambezi basin everywhere below the Victoria Palls. Therefore this region may be separated naturally into two sharply-marked divisions: — (1) The unbroken plateau with mature drainage-features ; and (2) the region of rejuvenated drainage. In ground-plan the boundary between these divisions forms a succession of gradually deepening loops around the tributary streams, and, as already mentioned, steadily recedes from the main river on both sides as it goes eastward. Between the network of gorges that characterizes the second division there are irregular patches of flat ground, representing fragments of the old plateau ; but this country is almost everywhere rugged and stony from the ready transport of the surface-products of weathering into tbe gulches by the torrential rains. Where 1 A. St. H. Gibbons, ' Africa from South to North through Marotseland ' (London, 1904) vol. i. pp. 65-66 ; andC. Hardiog, ' In Remotest Barotseland' (London, 1905) pp. 319-20. Yol. 6$.~] GEOLoar of the Zambezi basin. 16$ not too steep, the ground is covered more or less thickly by scrub and low trees, interspersed with a scanty growth of tall harsh grasses. At the time of our traverse, in the long drought, the streams were dry or merely trickling, the trees mostly leafless, and everything was parched and still ; but during the rains (November to March), when floods are roaring through all its ravines, this must indeed be a turbulent region. On the outer fringe of this broken country the strips of original plateau between the ravines become broader, and frequently include truncated segments of shallow valleys, showing where the youthful drainage is destroying the older system. The present streams possess similar shallow troughs farther back, where the plateau is as yet intact ; and most of these break off suddenly at a deep waterfall or a series of cascades, below which the stream is at once engorged, like the Zambezi itself at the great Palls. Thus the valleys of the upland stand in the relation of ' hanging- valleys ' to the low-level drainage. These shallow troughs of the plateau-streams are generally bordered by low slopes of greatly decomposed basalt, and their broad floors are covered with dark stiff loam or earthy clay, not often exceeding 3 or 4 feet in thickness, apparently derived partly from the rotting rock upon which it rests and partly from the dense growth of tall rushy grasses which it nourishes. The stream- channels along these flats are somewhat canal-like, showing an alternation of long narrow pools where the basalt i3 most readily decomposed, with low bars of bare rock where weathering is less effective. During the season of drought, water is retained in the pools long after the stream has ceased to flow ; and further aid is thus lent to the decomposition of the rock beneath them, which leads to the rapid excavation of deep crevice-like gorges (Pis. X & XV & fig. 8, p. 191), often curiously angular, along the rotted belts as the rejuvenated drainage breaks back into the plateau. The grassy flats are generally bordered by a fringe of well-grown trees, while the low stony slopes of the valleys are covered with the bushy growth and scanty grasses that overspread the neighbouring plateau. But, towards the head of most of the streams, the grassy flats of dark earth expand into shallow basins ranging up to a mile or two in width and several miles in length. These sometimes become confluent and lose altogether their relation to any definite valley, the loam then thickening and spreading over gentle slopes in a manner somewhat similar to the peat of humid climates. The dark soil of such tracts is indeed called ' torf ' by the Boer farmers, but in composition it is quite different from peat. In the wet season it is a very tenacious clay, which retains the moisture and works up into a pasty mud ; and during the drought it contracts so greatly in drying that the surface is reticulated by gaping cracks which are very troublesome to the traveller. Of such tracts I saw the most striking examples in the upper basins of the Lukunguli, the Matetsi, and the Deka, but they are prevalent throughout the Q. J. G. S. No. 250. b- 170 ME. G. W. LA.MPLTJGH ON THE [May 1907, ****• \*\ «]»! Ill: district, especially south of the Zambezi, and appear to be still more extensive in the shallow basins of the Kalahari. Much of the plateau between these grassy depressions is covered deeply by rusty-red sand, occurring usually in broad gentle swells or ' bults,' which may be a mile or more in width and many miles long. These sand-bults occur on both sides of the Zambezi, but their propor- tionate area increases southward as the plateau merges gradually into the true Kalahari. From their capacity for retaining moisture these sands nourish taller trees and more vigorous vegetation generally than the rocky portions of the plateau. They are equivalent to the ' Kalahari Sand ' of Dr. Passarge, and must have been accumulated under cli- matal conditions very different from the present (see p. 201). On flat ground where the sand is absent the surface is for the most part thinly covered with a firm, rusty, lateritic soil derived from the basalt, through which protrude many blocks of partly weathered rock. In some places this soil, like the well-known laterites of India, is full of small hard pellets or tions, about the size of peas. The appended diagram (fig. 1) will serve to illustrate the physical features which we found to be con- stantly repeated in traversing the plateau along the margin of the newly-dissected country. There is a decided fall of the JJ.xi"! surface of the plateau towards the Zambezi both from the north and from the south, which appears to xQ * : reflect its original structure ; and the *jx]x; gradual sinking of the country east- ward until the Deka is reached is probably also structural. Hence the course of the Zambezi may roughly coincide with an original depression in the plateau, which has, of course, been greatly accentuated by loner-continued erosion. ferruginous concre- o *g w~. Yol. S^.'] GEOLOGY OP THE ZAMBEZI BASIS'. 171 IV. Geological- Structure. The main features in the geology of the region, so far as these are known to me, are broadly outlined, without pretence to accuracy in detail, in the accompanying sketch-map and sections (PI. XVII). On this map the following rock-systems are repre- sented : — (5) Kalahari Sand, with Chalcedonic Quartzite, etc. (4) Flaggy Sandstone of Boomka— ? Forest Sandstones (Molyneux). (3) Batoka Basalts. (2) Wankie Sandstones and Coal-measures =Matobola Beds and (?) Escarpment-G-rits of Molyneux. (1) Fundamental Complex (granite, schist, etc.). From the map and sections it will he seen that the great floor of ancient metamorphic and intrusive rocks, presumably pre- Palaeozoic, which underlies the whole region and emerges around the rim of the interior basin of Central South Africa, is deeply buried under newer rocks in the portion of the Zambezi basin included within my traverses. Except at one point, 3 or 4 miles south of the Wankie coal-mine, at the extreme south-eastern limit of my journey, I gained no opportunity for examining these oldest rocks in situ. The overlying Matobola Beds or Ehodesian coal-measures I examined in some detail, in their outcrop between the Wankie mine and the Deka Eiver ; but elsewhere my routes lay almost entirely over the basic lava-flows which constitute the Batoka Basalts, or over the superficial detritus by which these basalts are partly covered. (1) The Fundamental Complex. From Livingstone's mention 1 of the presence of granite in the upper part of the Kalomo river-basin, and of gneiss and mica-schist dipping away respectively westward and eastward from this granite-mass, we could surmise with some confidence that the Tijarida Hills, which rose within easy sight to the north-east of us after we crossed the Kalomo on our route north of the Zambezi, are composed of the ancient rocks ; and I was disappointed not to find the southward prolongation of this mass within our traverse. The shape of the ground indicated that the basalts did not extend to these hills (which for a time were not more than 10 or 15 miles distant from us), but that at least in one place the volcanic rocks ended off in a low escarpment fronting the hills. The only positive evidence, however, that I obtained in this quarter respecting the rocks to the northward of the basalts was from the detritus brought down by the Kalomo and two other south-flowing streams farther eastward, the Namaruba and the Grwemanzi. West of the Kalomo Eiver I had found no trace of any rocks other than basalt and the later chalcedonic quartzite in the stream-beds; and it was therefore 1 'Missionary Travels & Researches in South Africa' 1857, chap, xxvii, pp. 542, 543, & 548. AT 9 172 ME. G. W. LAMPLUGH ON THE [May I907, pleasing to find a pebble or two of grey granite in the stony flood- bars of this river, along with much mica, felspar, and pink quartz in its sand-banks. I may here mention also that among the larger blocks strewing the same river-bed were some masses of red basaltic breccia full of scoriaceous and bomb-like inclusions, more like a true eruptive breccia than any portion of the basaltic series in situ that came under my notice. In the next stream, the Namaruba, a few miles farther east, extraneous pebbles became very numerous, varied, and of large size, nearly one half of the stones being other than basalt ; and not only was there a varied assortment of igneous rocks among these, including pink and grey granites, pegmatite, syenite, gneissose schist, etc., but also many fragments of coarse reddish and grey sandstones and pebbly grit. This gravel was not confined to the stream-bed (a shallow trough on the plateau), but was also scattered plentifully over the slopes and eastward over a low watershed into the deeper valley of the Gwemanzi, 2 or 3 miles farther east. It is, therefore, a little uncertain whether the streams derived the material directly from outcrops of rock in their higher reaches, or at second hand from an ancient river-gravel ; but in either case the source must have lain to the northward, and at no great distance. The sandstone-fragments must, I think, imply the presence of a belt of sedimentary rocks to the northward, between the Batoka Basalts and the ancient massif ; and this inference receives support from other scraps of evidence, notably from the reported discovery of coal-bearing deposits in the country between the Victoria Falls and Kalomo. Judging from the conditions observed in the Wankie coalfield (see Section 2 of PI. XYII) and from the resemblance of the sandstone-fragments to the sandstones and grits associated with the Wankie coal-measures, it is probable that these sedimentary deposits north of the Zambezi rest directly upon the ancient complex, and are themselves overlain by the basalts ; but the junctions may, of course, be affected by faults of which I have no knowledge. As the railway has, since my visit, been carried north- ward past Kalomo to the Kafue River and beyond, we may expect ere long to obtain more definite information regarding the geology of this region ; and meanwhile I have ventured to draw the hypo- thetical boundaries shown on the map, interpolating the Wankie Series between the Batoka Basalts and the Fundamental Complex, as an indication of the present state of our knowledge, and as an incentive to anyone who may find opportunity of proving its inaccuracy. If we turn now to the country south of the Zambezi, we shall find that, on the strength of a statement by Chapman,1 Dr. Passarge has inserted on his map 2 an inlier of the ancient rocks, surrounded by the basalts, near the head of the Deka river-basin. With the hope of learning in this quarter something of the rocks underlying 1 ' Travels in the Interior of South Africa ' vol. ii (1868) p. 212. 2 ' Die Kalahari ' 1904, Kartenband, Blatt ii. Vol. 63.~] GEOLOGY OF THE ZAMBEZI BASIX. 173 the Batoka Basalts, I made a long journey to the place indicated, at the site of the old hunter's camp known as Deka; but with disappointing results. The basalts were still the lowest rocks visible there ; nor could I detect in the surrounding featureless country any indication that promised change, or any trace of rocks other than basalt and chalcedonic quartzite in the scanty detritus of the stream-beds. To the southward of this place the shallow depression which constitutes the head of the Deka basin appeared to merge almost imperceptibly into the great wilderness of the Kalahari ; and although, in such a country, it is easily possible for one to miss a vaguely-defined locality, the impression was strongly borne in upon me that the search was hopeless, and that in this quarter the Batoka Basalts are prolonged without inter- ruption south-westward under the superficial desert-formations of the Kalahari. It may be that Chapman's observation ' near the source of the Luluesie (Daka) ' of ' a vertical stratum of sandy schist' (oj>. tit. pp. 212-13) refers to some place farther eastward, where a prolongation of the boundary-fault of the basalts is likely to occur ; or it may refer only to the thin sandy flags, presently to be described, that were seen to overlie the basalts in a limited tract north-west of Deka (p. 196). At the one locality, some 3 miles south of the Wankie coal- mine, where, as previously mentioned, I gained a glimpse of the old rocks, they emerged from beneath the "Wankie Series in the manner shown in PI. XVII, Section 2. The exposure occurred in a rugged gully eroded through the sandstones, at the foot of a high steep ridge which my friend and guide, Mr. J. M. Kearney, Manager of the Wankie Mines, has since ascertained to be also composed -of sandstone. In this gully, the rocks which came within reach of my hasty examination (with night approaching, and no chance to revisit the spot) were a schistose quartzite and a highly sheared coarse- textured rock resembling a conglomerate with crushed pebbles of felspar, but possibly a much-deformed pegmatite. Judging from a rough sketch-map accompanying an engineer's description of the Wankie coalfield published in 1902,1 this exposure probably forms the western end of a long spur jutting out from the main mass of the ancient igneous and metamorphic series lying to the south-east in the region described by Mr. P. P. Mennell.2 (2) The Wankie Sandstones and Coal-measures. During a stay of four days at the "Wankie coal-mine, I was enabled, through the facilities afforded to me by the kindness of Mr. J. M. Kearney and his staff, to make three traverses of the sandstone-country between the railway-line and the Deka River, 1 Anon. ' Colliery Guardian ' vol. lxxxiii (Feb. 21st, 1902) pp. 390-92. 2 'The Geology of Southern Ehodesia' Special Eeport No. 2, Rhodesia Museum, Bulawayo, 1904. 174 . ME. G. W. LAMPLTJGH ON THE [May I907, up to the margin of the Eatoka Basalts. My foremost object was to determine the character of the junction between the basalt and the sandstone-series ; but in doing this I obtained some knowledge of the structure of this coalfield. The engineer's report above cited contains a rough diagrammatic section across the field, and some details respecting the succession of the coal-measures. The Wankie coalfield is referred to, but not described, by Mr. Molyneux in his paper on 'The Sedimentary Deposits of Southern Rhodesia ' 1 ; and he classes these deposits, along with those of other Ehodesian coalfields, under the term Matobola Beds. Mr. Molyneux seems, however, to have had in mind the probability that the next higher division of his scheme of classification — the ' Escarpment Grits ' — was likewise represented in the district 2 ; and I think that this is indeed the case. Athough no fossils had been found in this field, Mr. Molyneux obtained some palseontological evidence from other areas in favour of the 4 Permo-Carboniferous ? age of the Matobola Beds, which thus fall into line with the coal-bearing deposits of the Transvaal and Natal. Some ill-preserved plant-remains which I collected near Wankie lend support to this conclusion. The series developed around Wankie consists mainly of massive irregularly-bedded sandstones, generally coarse in grain and some- times rough and pebbly, with subordinate beds of micaceous sandy shale, clay -shale with ironstone-nodules, carbonaceous shale, and coal. The fine-textured deposits are subject to rapid changes laterally, but on the whole tend to occur as a middle division between the massive and more persistent sandstones.3 These softer middle beds are well exposed in the hollow in which the coal-mine is situated, while the rugged kopjes to the north and south of it reveal under- lying and overlying sandstones. The beds frequently swing into broad dome-shaped undulations, but dip as a whole northward. The succession across the hollow about a mile south-east of the mine is shown in Section 2 (PI. XYII) ; and 4g miles farther west, near the old Palls road, the sequence is as in Section 3 (PI. XVII). On traversing the interveniug ground, my impression was that these two sections were complementary, the base of the second (No. 3) being stratigraphically a little above the top of the first (No. 2) ; but my examination was not sufficiently close to eliminate the possibility of duplication by cross-faulting, which is suggested by the points of resemblance in the sections. The curious ferruginous crust on the upper surface of some of the massive grits where these are overlain by shale, and the local induration of the top of the grit beneath this crust into quartzite, is noteworthy, as alteration of similar type appears to be still in 1 Quart. Journ. Geol. Soc. vol. lix (1903) p. 281. 2 Ibid, table on p. 278. 3 In the general section given in the report published in the ' Colliery Guardian' vol. lxxxiii (1902) p. 392, three main sandstones are recognized, and are respectively named ' Upper, Middle, and Lower Grits.' Vol. 63.~] GEOLOGY OF THE ZAMBEZI BASIN. 175 progress among the superficial formations of the plateau. The thin band of peculiarly indurated shale, apparently silicified, upon the lower sandstone in the second section (Bed 4, Section 3) is probably a further result of the same process. Another rock of unusual aspect associated with this sandstone is the ferruginous claystone, which is sprinkled with concretionary spherules of deep-red haematite, about the size of large oolite-grains and having a radial structure internally. In colour, the sandstones vary from dull-red to pale yellowish- grey, the paler tints predominating. While some beds are marked by distinctive tints, there is also in places a mingling of the red and grey tints in the same bed. Both in colour and texture, these sandstones recall the characters of the familiar English Bimter Sandstones ; and the likeness becomes accentuated in the pebbly beds occurring in the higher part of the series, the pebbles having the same thoroughly rounded outlines and the same scattered distribution as in the pebbly sandstones of the Bunter. This similarity I noticed especially in the steep kopje at 'Mtoro's Kraal. The thicker sandstones are strongly jointed, one set of joints striking east-and-west like those of the basalt-country, with other cross -joints striking approximately north- and-south. In the stream-beds, the rock is sometimes eroded along these joints into deep crevices ; as, for example, in a dry stream-bed 3 or 4 miles west of Wankie, where one crevice of this kind, which crosses the stream-bed at right angles, is 8 or 10 feet deep and not more than 2 feet wide. On the top of the kopjes, these jointed sandstones often weather into huge blocks of fantastic outline ; and in the precipitous krantzes the scaling away of the rock along the joints gives a botryoidal aspect to the exposures. Prom the remarkable scantiness of superficial covering, which characterizes the whole region except in the sand-bults and loam- flats, the sandstones crop out in many places in absolutely bare platforms of wide extent, but with numerous bushes and trees rooted in the crannies ; and in this manner the weathering and subsequent erosion along the crevices is evidently facilitated. One of these bare platforms, about a mile east of Wankie, was curiously pitted with hollows, and also contained, embedded in its surface, a few small lumps of silicified wood, not rooted like trees but looking as if derived in their present condition from some older deposit. The pittings appeared to be the casts of similar lumps which had been removed. Some blocks of silicified wood of the same character were found lying loose, along with a sprinkling of quartz -pebbles, on the surface of the basalt adjacent to a bold ridge of sandstone, in the Deka basin, 6 miles east-north-east of our Bumbusi camp, one being a segment of a stem 15 inches in diameter, showing a well- marked core ; and these blocks, like the accompanying pebbly detritus, have no doubt been derived from the sandstone. Near the place where the lowermost sandstones abut upon the previously described spur of ancient schistose rocks south of 176 THE GEOLOGY OE THE ZAMBEZI BASn*. [May I907, Wankie, I noticed a few rounded boulders of schistose quartzite, up to 8 or 10 inches in diameter, embedded in the sandstone ; but I did not, at the time, appreciate the suggestiveness of the fact as a possible indication of the horizon of the Dwyka Conglomerate. I must be content, therefore, to throw out the hint, in the hope that it will attract the attention of some future worker to this place. In the carbonaceous sandy shale (Bed 3 of Section 2) exposed at the Wankie railway-station and in a bank near the entrance to the mine, obscure fragments of plants are abundant ; while in the shale forming the roof of the mine, Mr. Kearney pointed out to me some crushed reed-like stems measuring several feet in length, and 3 or 4 inches in breadth ; but all were too imperfectly preserved for determination. I obtained rather better specimens, however, from a brown silty shale in the section 4^ miles west of Wankie (Bed 5 of Section 3) exposed in a little gully between the old wagon-road and the railway, here running within 100 yards or so of each other. Among these specimens, Prof. A. C. Seward has recognized fragmental Vertebraria; and if this fossil is, as supposed, the stem of Glosso- pteris, it confirms Mr. Molyneux's correlation of these measures. In the character and predominance of the sandstones; in the prevalent sandiness of the shales ; and in many other features, these deposits differ greatly from our British Coal-Measures, and indicate very different conditions of accumulation. The grounds on which a belt of the Wankie Series is inserted on the map (PI. XVII) to the northward of the basalts have already been stated (p. 172) and require no further discussion. The- Deka Fault. On finding that the monotonous basalt-country, after sinking steadily eastward, came at last to an abrupt termination at the foot of the steep hill-range of sandstone and quartzite bordering the southern side of the Deka Valley, my first impression was that the Batoka Basalts had shelved underneath the sandstones; and, although there were difficulties in the interpretation, it was with this idea in mind that I reached the Wankie coalfield. But the idea became untenable when I ascertained that metamorphic rocks, and not the basalts, emerged on the south from beneath the coal-series. Returning to the Deka, therefore, to make further examination, I soon obtained clear evidence that the junction was in truth a line of faulting, the actual fault being well exposed in the river-bed near the Deka railway-bridge, within a mile below the place where I had first crossed the junction. By another journey northward from Wankie to the Deka, at the confluence of its tributary the Eondulu, some 7 or 8 miles lower down the valley, I was enabled again to intercept the fault, which was here even more strikingly displayed. It then became evident that a faulted junction of the Fig. 2. — Sketch-plan showing the loop of the Beka River at the great fault, near the confluence of the Rondidu River. %, [Scale: 1 inch = l mile.] The ridge of pebbly sandstone rises 500 feet above the river, and forms high cliffs at the bend. The rock, altered to quartzite and much shattered and veined, plunges steeply as it approaches the fault, which is well exposed in the bed of the river, and also in the Rondulu stream-bed. Pig. 3. — Sketch-diagram of the fault along the Deka River, about a mile belovj the railway-bridge, looking north-eastward. N.W. S.E. a = Rugged kopjes of coarsely porphyritic basalt, breaking into a cliff above the river in the foreground. b = Conical kopje, about 200 feet high, in the middle distance, ex- hibiting the fault in a river- cliff at the bend. Vertical bands of quartzite, much veined and shattered, occur on the right side of the fault. c = High bluffs of pebbly sandstone, extending in terraces which reach the right bank of the river. 178 MR. G. W. LAMPLTJGH ON THE [May I907, sandstone and basalts which I had previously noticed at 'Mtoro's Kraal, 8 or 10 miles west-south-west from the Deka railway-crossing, lay approximately upon the opposite continuation of the same fault- line, although I had at the time thought it of slight consequence. My personal knowledge of the faulted belt thus embraces a distance along its direction of 16 or 18 miles ; but there is evidence that it is much farther prolonged in both directions, and is a structural feature of prime importance in the geology of the region.1 The phenomena associated with it are also of sufficient interest to deserve particular description. In the segment that came under my observation, the strike of the fault is from west-south-west to east-north-east. For a long distance its course coincides very closely with that of the Deka valley : not, however, that the valley is a fault-trough, but because of a secondary effect presently to be discussed. It was long ago observed by Chapman, whose testimony should in itself have led one .to suspect the faulting, that — • ' The Luluesie or Daka Kiver is the limit of the basaltic rocks, presenting formidable cliffs of red sandstone, while the western banks have at intervals mural cliffs of basalt, and thus throughout the whole distance which I traversed (upward of 80 miles), I have seen no red sandstone west of the Luluesie, nor basalt east of it, excepting only in the banks where the river, by an abrupt bend, has encroached on either side a little.' 2 Some details of the fault at the places where I had the best opportunity for examining it, north and west of Wankie, are shown in the plan (fig. 2, p. 177) and diagrammatic sketch (fig. 3), and in Section 3 of PL XVII. Its course and probable prolongation are represented on the map ; but in this I have been greatly hampered by the uncertainty of the topography, especially with respect to the position of the localities in the upper part of the Deka basin, between Deka and 'JNgoni's Kraal, which may be several miles from their true bearings on the fixed position of Wankie. The fault affects in a striking manner the sandstones which abut upon it. In all the places that I examined, except in the transverse valley of the Eondulu Eiver, these sandstones are of the red coarse- grained or pebbly type, and appear to belong to the ' Upper Grits ' of the Wankie Measures, as indicated in Section 3 (PL XVII). In some places (fig. 3, p. 177) these sandstones plunge steeply as they approach the fault, and are not only greatly crushed and contorted, but are also converted into quartzite and much veined with quartz and haematite, thus producing a highly indurated belt bordering the dislocation. The basalts are also affected, but in an opposite manner, the altered rock along the fault yielding more readily to the weather 1 Since the above was written I have received a letter from my friend Mr. Kearney, in which he informs me that he has recently traced the fault south- westward for 30 miles, from Wankie to Bumbusi, and finds its course to be parallel with the road that I followed and sometimes within a few hundred yards of it, as I had suspected (see p. 181;. 2 < Travels in the Interior of South Africa ' vol. ii (1868) p. 213. Vol. 6^.~] GEOLOGY OF THE ZAMBEZI BASIN. 179 than does the unaltered basalt. Thus there has sprung iuto existence a range of high kopjes marking the course of the indurated sandstone, with lower ground on the one side due to the more rapid disintegration of the unaltered sandstone, and on the other side due to the decomposition of the basalts. At the same time, as a whole, the basalts are less enduring under the African climate than even the unaltered sandstones, so that there has been relatively a general lowering of the country on the basalt side of the fault. The presence of a few high flat-topped kopjes of approxi- mately equal elevation on the opposite sides seems, however, to indicate the former existence of a plateau, before the initiation of the present drainage-system, on which there was no conspicuous feature to mark the fault ; and this condition should be borne in mind in any attempt to trace the fault south-westward into the unbroken plateau beyond the head of the Deka basin. The effect of the fault upon the course of the Deka River now requires notice. As previously mentioned (p. 173), the upper portion of this river, so far as it came under my observation, lies ■wholly within the basalt-country, the two main branches of its head- waters, which unite a short distance below Mr. Geise's ranch at Deka, having shallow channels on the surface of the plateau, while below their confluence the valley is still sunk but little below the general level of the hummocky plain of basalt. This open valley is continued for many miles ; but afterwards gives place to a steep-sided gorge, the change setting in somewhere between 25 and 35 miles east-north-east of Deka, in a portion of the river-course which I was not able to examine. This steep trench where we struck into it near 'Ngoni's Kraal was still entirely within the basalts, though the high kopjes of sandstone marking the great fault ran almost parallel with the canon within 2 or 3 miles to the south. About a mile above the place where the railway crosses the Deka, the river swings up to the foot of the sandstone-kopjes, but rebounds from them in a sharp curve ; and in this neighbourhood the valley has lost for a time its canon-shape, through the disappearance of its north-western or basaltic wall. Immediately below the railway- bridge, the river runs for nearly a mile almost exactly along the junction between the two rocks, as shown in fig. 3 (p. 177), once or twice impinging upon the hardened sandstone, but swinging off sharply again as if rebounding from the impact, and finally sweeping away northward into the basalt-country in a bold curve. These phenomena are repeated almost exactly near the Rondultr confluence, 7 or 8 miles farther down stream, where the river returns with a south-easterly course from its incursion among the basalts, and again impinges upon the fault, managing to carry one sharp loop of its bed just within the sandstone-boundary before being driven off again into the basalts (see fig. 2, p. 177). The presence of several low streamless ' poorts ' or cols gapping the high ridge on the sandstone side of the fault suggests that the river may at some past time have broken through the belt ; but ISO ME. G. W. LAMPLUGH ON THE [May I907, whatever its original course may have been, its present direction is clearly determined by this hard barrier. Nor is the influence of the fault likely to be confined to the Deka valley, for it is highly suggestive that the great northerly bend of the Zambezi itself east of the Deka confluence should coincide very closely with the position and direction which this fault will have if prolonged north-eastward. That it is indeed thus prolonged is supported by travellers' records regarding the Gwai River near its confluence with the Zambezi : from the descriptions of Chapman 1 and Mohr 2 we gather that the sombre gorge of the Gwai at some little distance above the confluence is eroded through massive sandstone, while the great trough of the Zambezi between the mouths of the Gwai and the Deka appears, from the accounts given by Chapman 3 and Major A. St. H. Gibbons,4 to lie within the basalts ; and the following sentence seems to show that Chapman struck the actual fault-line at a short distance south of the Zambezi : — 'A little valley coming into the Gwai, half a mile north of this [referring to the place where he reached the Gwai], seems to be the dividing point of the large square blocks, layer on layer, of hard red sandstone.' ( Op. cit. p. 193.) Furthermore, I am inclined to think that we have some evidence suggesting the continuation of the fault to the north-eastward far beyond the Gwai. In his account of the sedimentary rocks of Southern Rhodesia, Mr. Molyneux describes, under the term of ' Sijarira Series,' a great series of quartzites, indurated shales and current-bedded sandstones which form a bold hill-range (the Sijarira Range) overlooking the Zambezi flats some 70 or 80 miles east of the Gwai.5 These deposits he believes to occur beneath the Matobola Beds (coal-measures), which are supposed to rest upon them in strong unconformability. Mr. Molyneux several times makes particular reference to the evidence for crushing, faulting, and induration in the ' Sijarira Series'; for example, he remarks: — ' Where the quartzites or indurated rocks occur, it may often be noticed that there is a fault-fissure or displacement, and the axes of these movements take a north-easterly direction, or at right angles to the dip. Thus at Ohongolo the rocks are indurated on either side of a dyke of shale-and-sand stone crush- breccia. At the Lubu are parallel dykes of crush-breccia, made up of angular blocks of red sandstone, cemented by secondary white silica ; and at many other localities it is noticeable that movements have taken place along lines following a north- easterly direction, and have crushed the rocks into angular fragments, now cemented together. . . . 1 ' Travels in the Interior of Sou.th Africa' vol. ii (1868) pp. 193 & 212. 2 ' To the Victoria Falls of the Zambesi ' 1876, pp. 297 & 302. 3 ' Travels in the Interior of South Africa ' vol. ii (1868) p. 191. The rocks ' of a stratified or laminated appearance,' externally very black, and internally yellowish-brown, are probably the curious platy basalts presently to be described (see p. 193). The rocks containing agates, and those of ' a scaly appearance, like the scales of a bulb or onion,' are evidently basalts. 4 • Africa from South to North through Marotseland ' vol. i (1904) p. 93. 5 Quart. Journ. Gleol. Soc. vol. lix (1903) pp. 269-79, & sections, pi. xix. Vol. 63.~] GEOLOGY OF THE ZAMBEZI BASIN. 181 ' The regional alteration extends for some distance on either side of these lines of breccia, and the indurated rocks, resisting erosion better than the unaltered loose-grained sandstones, consequently form the core of the ridges, hills, and mountains of this part of the country.' l jSTow, when the Deka Fault is plotted on the map, its prolongation, so far as the present indefiniteness of the topography enables one to judge, will be found to fall very nearly along the escarpment of these Sijarira Quartzites as mapped by Mr. Molyneux; and I strongly suspect that the lines of disturbance described in the foregoing extracts represent the north-eastward continuation of the fault. Moreover, the phenomena are so closely analogous to those which I observed in the Deka Valley, that I shall venture to suggest that the ' Sijarira Series ' may be only the ' Matobola Beds ' contorted and altered along this great belt of disturbance.2 In the present state of our knowledge, this suggestion must of course be merely conjectural ; but it appears to fit most of the facts contained in Mr. Molyneux's description of the ' Sijarira Series ' and of the relations of this series to the underlying gneissose rocks and to the Matobola Beds. If the Sijarira disturbance proves to be no other than the Deka Fault, the sandstones, etc. of the Zambezi Flats on its north-western or downthrow side will represent some portion of the Matobola Beds of the plateau; and the steep northern face of the Sijarira Eange will approximately mark the fault-scarp. This reading is, I think, in accordance with our present knowledge — scanty, it is true — respecting the geology of the middle reaches of the Zambezi. Even if the Sijarira disturbance be not the direct prolongation of the Deka Fault, it must certainly belong to the same fault-system; and we may recall, too, that the strike of this fault-system is approximately parallel to the major axis of elevation in the ancient complex farther eastward pointed out by Mr. F. P. Mennell.3 As regards the prolongation of the Deka Fault in the opposite direction, up the Deka Valley, there is no doubt that its course was marked by the range of craggy sandstone-kopjes on the southern margin of the Deka basin, which we gradually approached after leaving Bumbusi on our march to 'Mtoro's.4 Farther south-west this feature evidently dies away into the plain of the Kalahari, where it is perhaps hopeless to expect that the fault will be traceable. From my examination of the fault itself at the places accessible to me I could gain no evidence as to the amount — or even as to the direction5 — of downthrow, owing to its effective severance of the 1 Quart. Journ. Geol. Soc. vol. lix (1903) pp. 279-80. 2 On suggesting this possibility to Mr. Molyneux in the course of our correspondence during the preparation of this paper, I am pleased to find that he regards it as quite worthy of consideration. 3 'The Geology of Southern Khodesia' Special Eeport No. 2, Rhodesia Museum, Bulawayo, 1904, pp. 8-9 & fig. 1. 4 See footnote on p. 178. 5 The breadth of the crushed belt obscured the hade of the fault in the sections that I examined ; but in two places — at the bend of the Deka east of the Eondulu confluence (fig. 2, p. 177) and in the kopje a mile below the railway- 182 ME. G. W. LAMPLTJGH ON THE [May I907, country into basalts on the one side and sandstones on the other, leaving no link between them. One is hampered also in attempting an estimate by the uncertainty as to the thickness of the basalts, regarding which we know only that it must exceed 1000 feet ; but by how much, it is impossible at present to conjecture (p. 195). Considering their total disappearance from the high ground on the opposite side of the fault together with the probable depth to which their base is sunk on their own side, it is not likely that their downthrow at the fault is less than 2000 feet ; and it may be very much more. The fact that all the basalts should have perished from the upthrow side and that the country should have been planed down to its present condition on both sides, denotes considerable antiquity for the fault. It will be noted that this great dislocation throws inward towards the centre of the continent, and may therefore have lent aid in the construction of the interior basin of the South African plateau. (3) The Batoka Basalts. Under any conditions, large areas of plateau-basalt are somewhat monotonous deserts to the stratigraphical geologist, and such to me the Batoka Basalts proved. During our long treks over their surface, I gleaned but scanty information on many essential points ; for which, perhaps, the necessity of following a definite route through the wild country may be partly responsible. Thus I nowhere saw their true base, nor did I find any recognizable vent from which these old lavas were poured ; and, what is still more regrettable, I did not light upon any intercalated sediments such as the previous descriptions had led me to expect. The Batoka Basalts present the usual characteristic of basic lavas, in maintaining great uniformity of composition over wide areas. All the varieties that were found may be included under the term olivine-dolerite, used in its wider sense. When massive, they form dark-blue heavy rocks, varying somewhat in the size and relative abundance of their crystalline constituents, and still more in the degree of development of a vesicular or amygdaloid al structure and in the composition of the amygdules. Stratigraphically these basalts present the usual trap or step-like features, due to the intercalation of thick bands of the more massive rock with thinner bands of less durable vesicular breccias which mark the under and upper surfaces of individual lava-flows. This structure is often excel- lently brought out by weathering in the walls of the canons and along the broken edges of the plateau, the hard bands protruding in bold scarps or ' krantzes,' and the slaggy breccias breaking down into inclines. bridge (fig. 3, p. 177) — the shattered sandstones seemed slightly to overhang the basalt, though with very little departure from verticality. I saw no indication of overthrusting, however, and do not think that the dislocation is actually a ' reversed fault,' though the basalts may perhaps in places have sunk slightly under the edge of the sandstones. Vol. 63.~] 'GEOLOGY OF THE ZAMBEZI BASIN. 183 At the Victoria Falls, the section in The Chasm reveals at least four massive beds, in thickness ranging from 40 feet to 80 or 100 feet, with intercalated breccias which show lateral variation in thickness from a few feet to 30 feet. It was observed, in excavating one of these breccias for the foundation of the railway -bridge on the western side of the gorge, that the rock though hard at the surface was comparatively soft within, the surface-induration being no doubt caused by mineral deposition from evaporating moisture — a condition of common occurrence throughout the region, especially in the more porous rocks. The Breccias. The breccias, which are usually red or pale ashy-green, vary greatly in texture as well as in thickness, swelling out occasionally into huge bosses of coarse agglomerate, in which some of the masses are vesicular and ' bomb '-like. I kept in mind the possi- bility that some of these might indicate the position of eruptive vents or ' necks,' but failed to detect any instance where this origin could be proved. In the bottom of the gorge at the confluence of the Songwi, 6 or 7 miles below the Victoria Falls, a thick mass of breccia, composed in part of huge angular blocks, was well exposed on the flood-platform of the river, and rose up at one place in crags over 30 feet high. This, at first sight, suggested a small vent ; but the mass could be traced as a definite band in the adjacent cliff, and was there underlain by the sheet of dense basalt which extended across the floor of the gorge ; and there was no sign that this basalt was anywhere pierced by the breccia. The absence of any other than basaltic fragments from all the breccias that I examined also tells against the probability of any of the breccias being truly eruptive. At two or three places while traversing the plateau, especially in the broken country immediately east of our route after crossing the Kalomo Eiver, we passed over areas in which the basalts lost for a space their usual tier-like aspect and became tilted, confused, and irregular, leading me temporarily to anticipate that we were approaching an eruptive focus ; and it is, of course, possible that in these places we may have traversed the outskirts of a volcanic centre without making a near approach to it. From previous information I had expected to find red sandstone interbedded with the basalts in the gorge below the Falls ; but all the red beds that I could reach proved to be stained breccias and not sandstones. As already mentioned, my search for interbedded sediments was fruitless throughout the district ; but this does not preclude the possibility of their occurrence beyond the area examined. Indeed, I saw from the train, in the Katuna valley (between Deka Bridge and Matetsi), some greenish-grey and reddish beds of shaly aspect among the basalts, unlike any rocks that I had the oppor- tunity of examining at close quarters. As the massive rocks also show much irregularity and variability in this neighbourhood, its 184 ME. G. W. LAMPLUGH ON THE [May I907, investigation may yield more notable results than I found myself able to attain. Some of the finer breccias present tuff-like characters ; and though it was my impression in the field that all the fragmental rocks that came under my notice were ' flow-breccias ' derived from the surface- shattering of the lava-streams, the petrographical examination of my specimens has shown that in at least one case, the composition of the rock cannot be entirely thus explained. A finely-fragmental rock collected from a thin band among hard platy basalts at the Mavangu creek, about 17 miles east of the Victoria Falls, has been found by Mr. Thomas to contain much clastic quartz ; which denotes either that the bed is a true tuff, or that it represents an admixture of land-waste with the basaltic detritus (see Appendix I [F 1018], p. 210). It is to be remembered that Mr. Molyneux l and Mr. Mennell 2 have described the intercalation of basaltic lavas with the ' Forest Sandstones ' of the country to the eastward, between Bulawayo and the Zambezi ; and that these lavas are assigned to the same period of volcanic activity as the Batoka Basalts — with which indeed they may at one time have been directly connected, though now severed by the Deka Fault. If this correlation be established, it will imply that sandy deposits of wide extent were accumulating contempo- raneously around the outer margin of the Batoka lava-field and were occasionally interbedded with the fringe of the flows ; and the sand-grains in the Mavangu breccia may be due to wind-drift from some such marginal area. The Amygdaloids. The basalts are prevalently amygdaloidal, sometimes only slightly and sometimes highly so, the cavities being filled sometimes with green-coated chalcedony or crystalline quartz or a combination of both, and sometimes with zeolites. The amygdules vary in size from a mere speck to 8 or 10 inches in diameter ; and I noticed a few isolated instances in which they assumed a pipe- or tube-like form. Around the Falls and in the higher part of the Batoka Gorge, zeolite-cavities predominate ; while in the country farther eastward, and especially in the floor of the canon in its lower reaches, quartz and chalcedony prevail as the infilling material. I sought to use this difference as an indication of the position of the basalts in the series, my impression being that the rarity or absence of zeolites marked the lower beds ; but, on descending the plateau as we approached Makwa, and also in the Deka valley, zeolites again became plentiful, although I judged that we there reached the lowest part of the series that came under observation. It is, however, 1 'The Sedimentary Deposits of Southern Rhodesia' Quart. Journ. Geol. Soc. vol. lix (1903) pp. 267-70. 2 'The Geology of Southern Rhodesia ' Special Report No. 2, Rhodesia Museum, Bulawayo, 1904, pp. 15-18. Vol.63.] GEOLOGY OP THE ZAMBEZI. BASIN. 185 possible that in this quarter the higher basalts are brought in again by disturbances due to the proximity of the Deka Fault. Among the zeolites in my collection Mr. Thomas has recognized stilbite, mesolite, and laumontite (?). Mr. F. P. Mennell also men- tions scolecite as occurring abundantly in the basalt at the Falls.1 The chalcedonic amygdules often possess a curiously minute botryoidal structure, their outer portion being made up of small globules showing concentric laminae, which give the material a pisolitie aspect. These and the many handsome varieties of agate would make pretty ornaments if polished ; and sooner or later the tourist will no doubt be able to purchase ' Zambezi Pebble ' trinkets at the Falls. Structural Features of the Basalts. The apparent absence of dykes and sills in the areas which I examined is noteworthy. In spite of the numerous deep sections that came under scrutiny in the walls of the great gorge and its branches, I saw no case where the nearly horizontal banding of the series was definitely interrupted. In some places, as for example at the sharp bends just below the Songwi confluence (PI. XVI), the weathered precipices of the Batoka Gorge are rendered jagged by the protuberance of sharp narrow spurs that at first sight suggest the presence of vertical bars of harder rock ; but, after as careful scrutiny as I could make by the aid of field- glasses, I came to the conclusion that in this and other similar cases the outstanding ridges and buttresses were simply the weathered remnants of peninsulas and ' knife-edges ' like those which divide the great zigzags of the river just below the Falls, and were of similar origin (see p. 187). Small dyke-like strings, showing a vertical arrangement, were occasionally visible on broad bare surfaces of basalt ; but when seen in cross-section these could not be traced downward below the lava-sheet on which they were displayed. They probably represent merely the infilling of cracks in the consolidated crust of the flow, from the yet fluid interior. On account of their differential weathering, these dyke-like veins sometimes have considerable influence in diverting the channels of the smaller streams ; as may be well seen on a bare platform overlooking The Chasm 50 yards beyond the western end of the Victoria Falls, which being occasionally covered by flood-waters is sharply trenched along the course of one of these veins. I suspected the presence of a discontinuous dyke at the truncated margin of the basalts along the Deka Fault; and this suspicion is partly sustained by the result of Mr. Thomas's petrographical examination (see Appendix I [F 1032 & 1035], p. 207), though the coarsely-crystalline rock near the Deka railway-bridge [F 1034], p. 210, on which my opinion was mainly based, proves to be less 1 Fourth Ann. Rep. Rhodesia Museum, Bulawayo, 1905, p. 2L Q.J.G.S. No. 250. o 186 ME, G. W. LAMPLUGH OX THE [May I907, dyke-like than I anticipated. As trap-like characters reappear in the basalts within a few yards of the fanlt in several places, the dyke, if it 'exists, can be of no great breadth. The so-called ' Mavinga Dyke ' shown on an engineer's sketch-map of the Wankie coalfield (see ante, p. 173 & footnote), though it happens to fall in the same position as this supposed intrusion, represents a misapprehension of the faulted junction of the basalts and sandstones, as it was evidently intended to include all the basalts seen beyond the fault. Dips. In a series of lava-flows the true stratigraphy is necessarily difficult to decipher, as the structural dip may be completely masked by their original inclination. Hence it is doubtful how far the dips that were observed in the Batoka Basalts are original, and how far superinduced. One thing is certain, that the surface of the plateau does not stand in simple relation with the original surface of the lava-field, but has been developed by erosion across the edges of the flows. The dips observed along our route are recorded, with other local information regarding the basalts, in tabular form in Appendix II (p. 212), which contains the details condensed from my note-book. From this it will be noticed that gentle south-easterly dips prevail for a few miles eastward from the Falls ; and that this direction is reversed for a space in the middle portion of the district, but reappears occasionally towards the eastern limit of the route. The dips, how- ever, are usually so low, that it would be unsafe to assign much significance to them ; and in the few restricted areas where com- paratively steep dips were observed, they might well be due to original irregularities. Nevertheless, it is almost certain that structural tilting of some degree would result from a dislocation of the magnitude of the Deka Fault ; and the evidence as a whole suggests that the dominant dip of the basalts is southward or south- eastward from the core of ancient rocks forming the Batoka upland, until they are intercepted by the great fault. On a broad scale, therefore, the basalts may be regarded as occupying a faulted syncline. Joints and other Fractures. The basalts are everywhere strongly and closely jointed, and the joint-system possesses a remarkable uniformity of direction over very wide areas. The prevalent direction of the governing set is approximately east and west, usually a few degrees — say 10° to 20° — north of east and south of west.1 There is also a tendency for other joints to be developed more or less at right angles to this set, which are however much less regular and in every way less conspicuous (see Appendix II, p. 212). As one might expect, the joints, especially the governing set, 1 From travellers' descriptions of the country north and north-west of the district here described, it may be gathered that east-to-west jointing and faulting is extensively developed in this part also. Vol. G^.'] GEOLOGY OF TflE ZAMBEZI EASIX. 187 are much more strongly and closely developed in the massive basalts than in the breccias and slaggy amygbaloids. The columnar appearance which is often conspicuous in the walls of the gorge is usually due to the emergence of close-set parallel joints on the vertical faces of the more massive beds. The only place at which I saw really well-formed columnar structure was iu a low cliff overlooking the ']Nongu, an eastern tributary of the Kalomo River ; although in a few other places, as, for example, in the main gorge at the confluence of the Karamba, the basalt showed a tendency towards wide-spaced polygonal jointing, without system or regularity. Besides possessing this joint-system, the basalts are also sliced at intervals in the same approximately east-to-west direction by pronounced fractures, along which there are sometimes signs of actual displacement; the opposing rock-faces showing slickensides and brecciation, with the occasional intercalation of vein-stuff, principally calcite and chalcedony. That vertical movement has occurred along these fractures is certain, but the monotonous character of the basalts generally renders its estimation impracticable. In one case, however, just above Kalonga's Cleft on the Karamba (see fig. 8, p. 191, and PI. XV) where the throw of a very conspicuous fracture of this kind could be measured, it was only 3 or 4 feet. These fractures tend to run in belts, within which they recur at short intervals, forming veritable ' shatter-belts/ They probably represent the minor re-adjustments of the great subsidence that finds its main expression in the Deka Fault.1 As we approached this fault in descending the Deka valley, veins of calcite were particularly conspicuous in the basalts, all striking approximately parallel to the fault. Effect of the Joints and Fractures on the Drainage-Channels. Both joints and ' shatter-belts,' but especially the latter, form vertical planes of rapid erosion, which, though invisible on the surface of the plateau where the stream-gradients are low, are picked out very rapidly into deep troughs by the forceful torrents rejuvenated by the recession of the main gorge (see p. 168). And as these structural planes frequently lie athwart the water-courses of the plateau, they constantly give rise to sharply-angular diversions from the previous direction where the streams plunge suddenly down- ward on leaving the upland. This effect is produced the more readily owing to the enormous seasonal variation in the volume of drainage. Except the Zambezi, almost all the stream-beds of the country traversed are mere flood-channels, filled to the brim for short periods during the rains, but during much of the year either quite 1 One of these veins, over 2 feet wide, which we crossed when about 12 miles south-west of Bumbusi, was entirely filled with calcite in very large crystals, and was seen to the east and west of our track for at least 40 or 50 yards. In a country where limestone is scarce, it is possible that this material may eventually become of some economic value. o2 188 ME. G. W. LAMPLTIGH ON THE [May 1907. Fig. 4. — Section about half- way down in the cleft at the eastern end of the Chasm at the Victoria Falls, showing the vein to which the chasm is clue. [The vein, as a whole, has a decided hade to $he south. The unshaded spaces are hidden by talus.] a = "Vein-stuff, partly vertical ribs of crystalline calcite, and partly red and purple decomposed rock and earthy material ; 4 feet seen, but probably 4 feet more in places, hidden under debris. b-A small 'stringer' of crystal- line calcite, 1 to 3 inches in width, cutting off a 'horse' or wedge of basalt. yy= Massive basalt, amygdaloidal in places, with strong east-and- west jointing which is cut at a low angle by the vein. dry or maintaining a very feeble flow. Hence, when a gully is formed in the stream-bed it soon serves to trap the whole flow except during tem- porary floods ; the erosive activity of the stream is thus concentrated along the trench ; and it is steadily enlarged until even the flood-waters cannot escape from it, so that the rest of the bed is abandoned. The grandest illustration of this method of erosion is afforded by the weird zigzags of the great gorge immediately below the Victoria Falls ; but these have been so fre- quently described that it is unneces- sary for me here to enter into details regarding them. I have elsewhere shown l that the mile-long transverse Chasm into: which the waters of the Falls descend has been scooped out along one of the vertical fractures, as I found on scrambling down its eastward termi- nation, where the section illustrated in fig. 4 was revealed. The deep cleft which notches the lip of the Falls on Cataract Island, illustrated in PI. X, is due, as Mr. Molyneux has pointed out,2 to the erosion of an oblique fracture by a small overflow-channel from the upper river. It exemplifies the de- velopment of a trench along a weak plane, which, if it should happen to strike diagonally up-stream above the present Chasm, may eventually capture the whole river and lay dry the broad lip from which the water now plunges. At many spots within the great gorge high above the present river I saw traces of abandoned channels 1 ' Notes on the Geological History of the Victoria Falls,' in the ' Official Guide to the Victoria Falls ' compiled by F. W. Sykes, Conservator (Bulawayo 1905) ; re- printed in Geol. Mag. dec. v, vol. ii (1905) pp. 529-32. 2 ' The Physical History of the Victoria Falls' Geogr. Journ. vol. xxv (1905) p. 51. Yol. 6^ GEOLOGY OF THE ZAMBEZI BASIN. 189 overhung by picturesque buttresses and isolated pinnacles, carved by the Zambezi in its search for the easiest passage when entrapped among the transverse trenches. Generally, where the river breaks away from these trenches, they are continued as deep rain-gullies into both walls of the canon ; or they form the subsidiary canons of tributary streams, into the waters of which the Zambezi itself may penetrate for some distance at times of high flood.1 These features are admirably illustrated in the broad floor of the gorge at the Tshimamba Cataracts, shown in the sketch-plan below (fig. 5) and Pig. 5. — Sketch-plan of the Batolca Gorge at the Tshimamba Cataracts, showing ivater-jUled inlets and steep gullies prolonging the east-and-ivest reaches of the Zambezi beyond its angular bends. (Approximate scale : 2 inches — 1 mile.) The water-area at the dry season is shown in black, and the dotted line marks the space covered at floods. in PI. XIII, where the river, at low water, twice forms a X in breaking away from its east-to-west trenches. At this place I found it not easy to determine whether the placid water of the straight reach on the south came into it from the east or from the west, even when I had traversed the flood-flat and stood at its rectangular termination. As a typical example of the effect of these structures on the 1 From Chapman's description it would appear that the gorge of the Gwai inust also be of this character at its mouth. 190 THE GEOLOGY OF THE ZAMBEZI BASIN. [May 1907. Fig. 6. —SLetch-plan of the gorge of the Karamba River, from above Kalonga's Cleft to its confluence with the Zambezi. ■45»= C^P.qJ>^W^1 ^f? "}TrCieft [+ = Yiew-point of PL XIV.] Fig. 7. — Profile of the river-bed at the waterfall above Kalonga's Cleft. Gully intercepting dry-season stream SO|"N smaller streams, we may take the ease of the Ka- ramba River, which joins the Zambezi on its north- ern bank, 35 miles east of the Falls, and reproduces neatly in miniature some of the principal character- istics of the great canon. This stream has carved out a wild gorge some 5 miles in length, into which it drops from an open valley on the plateau (see plan, fig. 6). The sides of this gorge at the mouth of the river, where they are 500 to 600 feet high, form bold rocky slopes rising at an angle of 30° to 40° from the stream-bed ; then they become gradually more precipitous as we proceed up into the sharp loops above the first straight reach ; their crests approach nearer and nearer to The dry-season water- gully is 20 feet deep at the line of section, but sinks to 50 or 60 feetfarther eastward. 192 . MR. G. W. LAMPLUGH ON THE [May I907, each other, until the walls are almost vertical ; and finally the gorge is narrowed to a profound cleft, 300 feet deep and only 15 to 20 feet wide at the bottom and about as many yards wide at the top (see PI. XV). At this gloomy spot, which we have named 'Kalonga's Cleft,'1 the gorge turns at right angles and holds a sombre, cliff-bound water-pool. Into this pool the Karamba, when shrunken with the drought, makes a sideway leap from the plateau ; but when flooded it must pour over the terminal wall in a terrific cascade occupying the whole breadth of the chasm. Between the water-pool and the lip of the shallow upper valley, the basalts and amygdaloidal breccias which form the precipice are sliced trans- versely to the valley by several vertical planes of fracture and crushing, with anastomosing branches, which have been gouged out by the stream into a series of deep riffies, as shown in the section, fig. 7 (p. 190) and bird's-eye view, fig. 8 (p. 191). At the time of our visit all the water was intercepted by the first of these riffles, and conveyed sideways to a lateral recess, from which it recoils at a sharp angle and leaps into the pool. Both as a spectacle, and as a most instructive lesson in the erosion of the basalts, I commend Kalonga's Cleft to the notice of any traveller who may find himself within reach of its flood-rent portals. Other Noteworthy Structures. At the surface, the basalt usually exhibits the familiar spheroidal habit of weathering ; but while in some places the rock is deeply rotted to a rusty earth or loam, in others it remains perfectly hard and fresh immediately beneath a thin scaly crust which is shed off almost as rapidly as it is formed. Yet there did not seem to be any difference in composition accompanying this difference in weathering. The same anomaly is, of course, sometimes noticeable in the basalts of temperate climates, but I have never seen the distinction so sharply marked as in the Batoka Basalts. The vesicular basalts occasionally show a kind of ' pillow- structure,' in the concentric arrangement of the amygdaloidal vesicles, due to the rolling-over of masses of half-cooled lava during the flow. This structure, so far as I saw, was not developed at the surface of the flows, but in their interior. The best example that came under observation was on the smoothly-worn rock-floor of the Mamba River, 200 yards below our camp, where the concentric outcrop of coarsely amygdaloidal bands divided up the rock into irregular oval masses, measuring from 2 to 6 feet in diameter. The more massive basalts, when fresh, occasionally show a curiously knotted aspect on stream-worn surfaces, somewhat resembling a spherulitic structure. This appears to be due to the segregation of the porphyritic constituents, especially the plagioclase- 1 Named after a native guide. Vol. 63.~] GEOLOGY OF' THE ZAMBEZI EASIX. 193 felspars, into small round clusters (see Appendix I [F 1030] p. 208). This structure was especially well seen in the bed of the Matetsi River, about a mile above the railway-bridge. Besides the flaggy or thick-platy arrangement such as is common in basalts, which was a constantly recurring character in every part of the series, I noticed in a few places an unusual fissile or shaly structure for which I could find no explanation. feo strongly marked was this structure in the bed of the Bwani River, 6 miles north of Makwa, where I first saw it, that I supposed the rock to be an indurated shale or schist, until closer examination showed it to possess the composition and crystalline character of the basalts. This shaly-looking material was, at one spot in the Bwani, curiously entangled among massive amygdaloidal basalt, with a sharp and irregular junction resembling an intrusive contact. Neither in the field nor under the microscope does the rock show any in- dication of shearing, so that the structure can hardly be a super- induced schistosity. Its petrographieal characters are described in Appendix I [E 1024, 1025, & 1026] p. 209. This shaly structure was also conspicuous on the southern shore of the Zambezi near Makwa, and was prolonged up the dry bed of the Gongobujo or Logier River ; and in a less striking form it was visible at a few other places, notably at the head of the Lukunguli River, south-west of Dambi's. From the description given by Chapman, we may gather that the basalts display a similar character in the Zambezi valley for some distance below Makwa.1 Extent of the Basalts. The eastern boundary of the Batoka Basalts at the Deka Fault has already been described; and I have also referred to the possibility that the basic lava-flows interbedded with the ' Forest Sandstones ' (Molyneux) of the country farther eastward may belong to this series (p. 184). The scanty evidence respecting the northern boundary as far west as the longitude of the Victoria Falls has also been stated (p. 172). As to their further westward prolongation, I have received information from my friend, Lieut. T. A. Gr. Budgen, who accompanied us during part of our journey north of the Zambezi, that he has recognized the basalts at a locality some 30 miles north- west of the Falls, in the bed of the Umgwezi or Marimba River, a west-flowing tributary of the Zambezi. There is, so far as I am aware, no further evidence until we reach the confluence of the Chobe 1 Chapman and Baines were evidently puzzled — and not without reason — by this rock. Chapman remarks : — ' Baines thinks that the rock in the bed of the Zambesi, at Wankie's, is what is called altered sandstone; it is a fissile or laminated brittle rock, with a glossy coating where influenced by water, but of a yellowish -brown colour inside (perhaps shale) .... The other grey scaly rocks seam [? seem] in it near to Wankie's. The outer scale of this rock is easily peeled off', and is brittle, but becomes harder towards the centre ' (' Travels in the Interior of South Africa ' vol. ii, 1868, p. 213 ; see also p. 191). 194 MR. G. W. LAMPLTJGH ON THE [May I907, or Linyanti River with the Zambezi, 50 miles west of the Victoria Falls, where Livingstone records the occurrence of amygdaloidal trap * ; while Aurel Schultz notes the presence of ' volcanic rocks ' along the Chobe above the junction.2 Above the Linyanti flats the Zambezi in its long and tortuous south-easterly course, for a distance of 75 miles, flows in many places over a rocky bed and is broken by numerous rapids ; and, according to Livingstone, ' the rapids are caused by rocks of dark-brown trap, or of hardened sandstone, stretching across the stream.' 3 The river is then confined within a shallow rocky gorge for several miles, at the head of which are the Gonye Falls, 20 to 50 feet high, according to the season. Livingstone's account of the geology of this place is as follows : — ' The rocks of Gonye are reddish grey sandstone, nearly horizontal, and perforated by madrepores, the holes showing the course of the insect in different directions. The rock itself has been impregnated with iron, and that hardened, forms a glaze on the surface — an appearance common to many of the rocks of this country.' 4 Serpa Pinto, however, describes the rocks of this locality (near Sioma) as ' basaltic strata .... forming natural ramparts, ever running east and west ' ; and he found similar rocks above the Gonye up to the edge of the Lialui flats 5 ; beyond which, for an interminable distance, the solid rocks are entirely concealed beneath the sands and loams of the plateau. The apparent discrepancy between the two accounts may, I think, be that Livingstone's description refers to a capping of the * surface-quartzite ' (see p. 198), beneath which the rock is probably basalt. At any rate, there can be no doubt that the Batoka Basalts extend westward across the Zambezi in some portion, if not in the whole, of its course between the Lialui Flats and the Linyanti Flats. Beyond the river, there is no hope of tracing the basalts, as the whole country for some hundreds of miles — right up to the western edge of the plateau — is a sandy plain over which several travellers have passed without seeing a single stone. Southward, as I have previously shown, the basalts may be followed along the outer margin of the Zambezi basin until they disappear under the sands of the Kalahari Desert, where the conditions are analogous to those on the western plains. Somewhere in the northern part of the desert, Chapman during his earlier hunting trips reached two solitary conical hills of * ironstone,' — the 1 ' Missionary Travels & Eesearches in South Africa ' 1857, chap, xiii, p. 233. 2 * The New Africa ' 1897, map. 3 ' Missionary Travels & Researches in South Africa' 1857, chap, xiii, p. 238. 4 Ibid. chap, xxv, p. 498. 5 ' How I crossed Africa ' English transl. vol. ii (1881) p. 83. Serpa Pinto's descriptions of the trench of the main river below the Glonye Falls, and of the minor trenches of its rejuvenated tributaries, are interesting, as showing a repetition of some of the characteristics of the Batoka Gorge on a small scale. The physiographical problems raised by the presence of this gorge so far within the plateau-country are too wide to be discussed in this paper. Vol. 63. J GEOLOGY OF THE ZAMBEZI BASIN. 195 ' Chenamba Hills ' 1 — which Dr. Passarge considers to be probably indicative of the re-emergence of the basalts ; but the position as well as the geology of these hills is uncertain. At the farther side of the desert south-westward, Dr. Passarge found the ancient gneissose and schistose rocks exposed in the neighbourhood of Lake jSTgami ; but if he is right in correlating the amygdaloids (' Loalemandelstein ') which emerge at the eastern fringe of the desert in the Palapye district with the Batoka Basalts, it seems possible that a considerable portion of the Kalahari between the Zambezi, the Chobe, and the Makarikari Saltpans may be underlain by these rocks. The basis for this speculation is however so slender, that it is not worth further discussion. Without extending the hypothetical boundaries far into either the western or the southern desert, we obtain an area of over 20,000 square miles as the approximate extent of the Batoka Basalts on a conservative estimate, and it may be very much more. But in any case the area of these old lava-fields cannot nearly attain the magnitude of the Deccan Traps of India or of the Snake-River Basalts of Western America. Thickness of the Basalts. As will be understood from the foregoing description, I found no means of ascertaining the thickness of the Batoka Basalts. It must in places exceed 1000 feet, as I saw nearly this thickness in a single section, in descending from the plateau south of the Zambezi to the bottom of the gorge approximately opposite the con- fluence of the Namaruba River; and at this spot presumably a very considerable mass had been removed from the top in the development of the plateau, and the base was still not exposed. What the thickness of the lava-fields in their deepest part may originally have been, must, I think, from the nature of the country, always remain a matter of conjecture. Age of the Basalts. Two views have been expressed respecting the geological age of the Batoka Basalts, but the evidence for either is at present slender. Mr. A. J. C. Molyneux,"2 whose opinion is endorsed by Mr. F. P. Mennell, considers them, as already mentioned (p. 184), to be probably contemporaneous with the similar basalts interstratified with the ' Forest Sandstones ' of the country which he examined, farther eastward. In the absence of palaeontological evidence, the age of the ' Forest Sandstones ' is left uncertain by Mr. Molyneux ; but Mr. Mennell considers them to be probably Tertiary, basing his argument chiefly upon the supposed recency of volcanic activity in i ' Travels in the Interior of South Africa ' vol. i (1868) pp. 150, 161, & 277-78. 2 'The Sedimentary Deposits of Southern Rhodesia* Quart. Journ. Geol. Soc. vol. lix (1903) passim. 196 MR. Gc. W. LAMPLUGH OK THE [May I907, the district,1 and this view of the age of the Batoka Basalts is accepted by Mr. Molyneux in his later description of the Victoria Falls.2 The second view is that implied in Dr. Passarge's above-mentioned correlation of the Batoka Basalts with the Loale Amygdaloid and Diabase (' Loalemandelstein '). Here again the age of the rocks with which the comparison is made remains itself uncertain ; but Dr. Passarge suggests that the ' Loalemandelstein ' may fall within the Jurassic Period, pertaining possibly to some stage of the great- epoch of volcanic activity represented by the Stormberg Series of the southern colonies.3 Further exploration will doubtless in time bring to light more direct evidence on the point ; but my own endeavour to obtain such evidence having been unsuccessful, I can only state my impression, based mainly upon the relation of the basalts to the physical structure of the country, that they are likely to prove older than Tertiary. That they are older than the planation of the great plateau of which they form part is evident from the structure of the country around the Deka Fault ; and if we dare follow Dr. Passarge in considering that this planation was largely accom- plished during a Mesozoic desert-period, the early Mesozoic age of the basalts might be taken as established. But this hypothesis of Dr. Passarge rests upon a highly speculative basis, and his evidence that the superficial deposits laid down upon the plateau carry back its history into Eocene times is by no means convincing. (4) The Flaggy Sandstone of Boonxka, etc. Along my route, the surface-sands and surface-quartzite presently to be described were usually seen to rest directly upon the Batoka Basalts of the plateau. At a few spots, notably along the northern edge of the sand-bult between Matetsi and the head of the Lukunguli basin,4 the sands were indurated towards their base into the condition of soft sandstone or ' sand-rock,' but the direct relationship between this semi-indurated material and the incoherent sand was clear. In going southward from Matheison's to Deka, however, I found traces of a flaggy, dull-red or green, siliceous rock overlying the basalt, differing in character from any material that I had hitherto seen and apparently representing the relics of a stratified deposit. It 1 'The Geology of Southern Rhodesia' Special Report No. 2, Rhodesia Museum, Bulawayo, 1904, p. 17. 2 'The Physical History of the "Victoria Falls' Geogr. Journ. vol. xxv (1905) p. 46. 3 ' Die Kalahari ' 1904, pp. 71, 82, 540-42 & Kartenband, Blatt ii. 4 The Lukunguli River is known to the natives by this name in its lower reaches only, toward its junction with the Matetsi ; its head-waters are known to them as the Jambezi.. It is probably the same stream as the 'Myatambesi' of Chapman's map, which has disappeared from the later maps. I intend further to discuss some of these geographical matters in the notes which I am preparing for publication in a geographical journal. Vol. 63.~] GEOLOGY OF THE ZAMBEZI BASIN. 197 occurred along the northern slope of the sandy plateau between the head-waters of the Matetsi and the Deka Rivers — an upland known to Chapman as ' Boomka,' although this name appears to be no longer current. Here, though poorly exposed, the flaggy rock seemed to underlie a loamy flat of considerable extent, and was visible along our route at intervals for 3 miles or more, the surface of several shallow depressions or dry vleys being littered with its debris. I thought at first that it might be only an abnormal silicified surface- bed of recent origin, pertaining to these vleys ; but on crossing for 4 or 5 miles the intervening sand-plain, I found similar rock crop- ping out along the edge of a shallow valley on the Deka side of the bult, under conditions implying that it might be the relics of a formation distinct from and older than the other surface-deposits. It differs from any of the surface-quartzites that I examined in its closely-knit fine-grained texture, flaggy bedding, colour, and general aspect ; and I saw nothing like it in any other part of our traverses. The surface of the slabs occasionally showed flattened cylindrical markings recalling the ' worm-tracks ' of some of our ancient greywackes. Microscropically, it is described by Mr. Thomas as ' a fine-grained quartzose sediment, iron-stained, and made up of very angular grains .... certainly not wind-blown ' (see Appendix I, F 1038, p. 211). Unfortunately, I saw no clear section in this deposit; but I think that its thickness where I crossed it can only have been slight — probably not more than 10 or 15 feet — as the basalts emerged in several places in the immediate neighbourhood. In the above- mentioned exposure at the margin of the little valley, the flaggy fragments frequently protruded edgewise at the surface, as if the beds possessed a steep dip ; but this tilting appeared to be merely a superficial condition, confined to the loose slabs. I mention this, because it is just possible that an exposure of similar character may have supplied the basis of Chapman's description of ' vertical strata of sandy schist (?) " x in and around the head of the Deka Valley, which was my main incentive in making this particular journey. These flaggy Boomka strata may conceivably be a feeble equi- valent of some portion of the similarly fine-grained ' Forest Sand- stones ' of the Bulawayo country ; or they may belong to the earlier of the superficial formations, like the ' Pfannensandstein' of Dr. Passarge ; but, without further knowledge, it is useless to attempt their correlation. Once more the absence of fossils — that perpetual hindrance to conclusions in South African geology — brings to mind Livingstone's striking apophthegm, l In Africa ; the very rocks are illiterate.' 2 Another exposure deserves notice here, as possibly indicating the presence of beds of a different character overlying the basalts. On the march from Deka to Wankie, about a mile before reaching 'Mtoro's Kraal, at the south-eastern side of the Deka basin some 15 miles distant from Wankie Station, a small steep hillock or 1 ' Travels in the Interior of South Africa ' vol. ii (1868) pp. Ill & 158. 2 ' Missionary Travels & Researches in South Africa ' 1857, chap, xii, p. 214. 198 ME. G. W. LAMPLTJGH ON THE [May 1907, kopje, isolated and of conical shape, lay close alongside our road on the left (north). This hillock was composed of shale with a capping of thin sandstone, apparently resting upon basalt. I made a hasty ■examination (near the end of a long trek), and the rough sketch in my note-book shows the following section : — Top of kopje (slopes clad with Euphorbia). Thickness in feet. Flaggy greenish sandstone 0|- Grreen marly shale 3 Purple shale 6 + on decomposed basalt? with platy structure, much hidden by talus. Hard amygdaloidal basalt-debris at foot of kopje. Note: Bedding of the shales nearly flat : looked rather promising for fossils, but none found. At the time when I saw this section I was of opinion that the basalts were shelving underneath the high ridges of sandstone that lay immediately to the right of our track, not having yet discovered the faulted character of the junction. Consequently, I did not pay such close attention to the evidence for superposition as I should afterwards have done ; but I distinctly remember that bare surfaces of basalt were exposed in close proximity to the kopje ; and this being on the downthrow side of the great fault, it seems impossible that the sediments can have been brought up by the faulting. The spot certainly deserves further investigation, which I hope that it will receive from the next geologist who may pass that way. (5) The Chalcedonic Quartzite, Kalahari Sand, and other Surface-Deposits. The Chalcedonic Quartzite.1 In many places the basalts of the plateau are overlain by a curious •siliceous rock that has figured largely in all travellers' descriptions of the country; for, although of insignificant thickness, it renders the ground which it occupies exceedingly uncomfortable to traverse. Frequently it occurs only as a chaos of loose blocks thickly strewn -over the flats ; but occasionally it attains a thickness of several feet, and from its resistant nature gives rise to conspicuous table- topped kopjes. The rock is a hard sandstone or quartzite, sometimes of a greenish tint, though more often reddish-grey or yellow. It is knit 1 For locally indurated patches in the superficial deposits of our own country, I have proposed the short terms, ' calcrete ' (when the cement is calcareous), ' silcrete ' (when siliceous), and ' ferricrete ' (when ferruginous) : see Greol. Mag. dec. iv, vol. ix (1902) p. 575 ; and despite the etymological faultiness of the first and second, I think that these terms might be very usefully applied to the indurated surface-beds of Africa. This particular rock I should describe, using the above nomenclature, as a ' silcreted' sand. There are strong objections to the application of the term ' quartzite 'to this material. Yol. 6$.^ GEOLOGY OF THE ZAMBEZI BASIN. 199 together by a chalcedonic cement, but is full of irregular cavities from which some soluble or incoherent material has seemingly been removed. Consequently,, while the rock is of flinty hardness, its surface is excessively rough and irregular, and therefore very damaging to foot-gear of any description. I found this quartzite or ' silcrete' to be very generally, though sporadically, distributed throughout the country along the margins of the sand-bults, often forming a broad ragged fringe between the sands and the bare basalt. It does not, however, form a continuous layer beneath the sand, as it was not encountered in a well sunk by Mr. P. W. Sykes near the residency at Livingstone through the sand to the basalt ; and is similarly wanting in some of the sand- cuttings on the railway between Deka Bridge and the Yictoria Palls. I saw some good sections of the ' silcrete ' along the eastern margin of the shallow valley of the Maramba River, 2 miles above Livingstone, where it occupies the surface of a little plateau 30 to 40 feet above the river-flat, apparently an old terrace of the Maramba, and is cut through in several little kloofs. It is here from 3 to 10 feet thick, resting on decomposed basalt : and has a brecciated aspect, rounded lumps of the chalcedonic quartzite being enclosed in a gritty siliceous matrix honeycombed with the usual irregular cavities. It is also well-displayed, as a rugged bouldery capping to small table-like kopjes, in the much-dissected country bordering the gorge of the Zambezi on the west in the basin of the Masui River, 4 to 5 miles south of the Palls ; and in this neighbourhood it is also seen along the eroded margin of the sand-bult, being there generally associated with hard ferruginous sand-rock. The greatest thickness of this surface-rock that came under my observation was in the sharp south-eastern rim of the Matetsi Valley, some 500 feet above the alluvial flat at Tsheza's, 5 miles from the mouth of the Matetsi. Here the beds cropped out at the margin of a high sand-covered upland in a bold krantz, which showed 8 to 10 feet of chalcedonic quartzite with 10 to 15 feet of partly siliceous, partly calcareous, brecciated or conglomeratic material below, resting on much- weathered spheroidal basalt. The position of this bed in relation to the valley appeared to denote its considerable antiquity. Thinner patches of similar chalcedonic rock occurred, however, on the stepped slopes along the opposite side of the valley at all elevations. Nor could I find in any part of the region that the formation was restricted to any definite position in respect to the present surface ; for although, as in the above-described instance, it frequently caps the highest ground, it occurs in abundance also on the lower terraces and even in the bottoms of valleys. The general impression that I gained was, that in most cases the * silcrete ' represents a progressive induration of the exposed base of the sands, due to the deposition of silica on the evaporation of ground- water which has slowly percolated through the sands. The 200 ME. G. W. LAMPLTJGH ON THE [May I907, solution and redeposition of silica, as Dr. Passarge has admirably shown, has been throughout their history one of the most character- istic geological processes within the great sand-velds of south-central Africa. The ' silcretes ' of the region which I traversed appear in all respects to resemble the surface-quartzites of Cape Colony- described by Mr. A. "W. Rogers * and his colleagues ; and, as with these, the conditions for their production still prevail. Therefore, while the induration of some may be of considerable antiquity, that of others is certainly very recent. From his study of similar deposits in the Kalahari Desert, where they attain their widest development, Dr. Passarge believes that a definite sequence of events may be traced in them, involving many changes of climatic conditions and dating back from Eocene times. Hence he divides these deposits into several stages, which are grouped together as a system under the term Botletle-Schichten. From the descriptions of travellers he has concluded that these i Botletle-Schichten ' are exposed with considerable regularity along the dissected edges of the plateau in the Zambezi basin below the Falls ; and he has therefore indicated their presence in this region on his map.2 However, as will be gathered from the foregoing account, I do not think that the suriace-deposits of the Batoka country afford support to the complicated hypothetical deductions which Dr. Passarge has drawn from the ' Botletle-Schichten ' of the Kalahari.3 In the country between Bulawayo and the Zambezi, Mr. Molyneux describes the occurrence of ' innumerable heaps of travertine,' com- posed of ' rounded quartz-grains cemented together by silica, often assuming the shapes of roots,' which form 4 the capping of small rises/ 4 These he considers to have been deposited by hot springs now extinct ; but I venture to suggest that in most cases they are surface-quartzites similar to those described above. The petrographical characters of two of the surface-quartzites are described by Mr. Thomas in Appendix I [F 1045 & 1046] p. 211. Blocks of the chalcedonic quartzite are among the commonest pebbles of all the streams that trench the ground which it occupies. The stone has been used in ancient times by the natives for manufacture into cutting implements. These implements lie scattered in large numbers on the rocky flats bordering the upper part of the Batoka Gorge : and, as I have elsewhere shown,5 some may be of considerable antiquity. 1 ' An Introduction to the Geology of Cape Colony ' London, 1905, pp. 357-61. 2 ' Die Kalahari ' 1904, pp, 540-42, & Kartenband, Blatt ii. 3 Ibid. p. 648. 4 ' The Sedimentary Deposits of Southern Rhodesia' Quart. Journ. Geol. Soc. vol. lix (1903) p. 282. 5 ' Notes on the Occurrence of Stone Implements in the Valley of the Zambesi around Victoria Falls ' Journ. Anthrop. Instit. vol. xxxvi (1906) pp. 159-69. Yol. 6$.~] GEOLOGY Of THE ZAMBEZI BASIN. 201 The Kalahari Sand. The mode of occurrence and the distribution of the surface- sands have been indicated in the first part of this paper, and are further illustrated by the section, fig. 1 (p. 170), and by the map (PL XVII). These red sands must attain a great depth in the broad smooth bults of the plateau, but are rarely exposed in section. In the well-sinking near Livingstone previously mentioned (p. 199) they were 20 feet thick ; in railway-cuttings south of the Victoria Falls they are exposed up to a depth of 15 feet: and these are the principal sections that came under my observation. Where untrodden, these sands are firm and compact at the surface, but they rapidly disintegrate and become quite friable under traffic. So far as I could find, they show no sign of bedding or other evidence of sedimentation ; and their position with regard to the present surface debars the possibility that they can have been accumulated as aqueous sediments where they now occur. For example, besides occupying the higher parts of the plateau, they enwrap the slopes of the shallow outer valley of the Zambezi in several places, and reach close up to the river on both sides above the Falls ; and I noticed similar conditions in several of the smaller open valleys. This gives some clue to the period of their accumu- lation, since it is evident that they have attained such positions at some time subsequent to the erosion of these particular valleys. But it is noteworthy that the sands on the opposite sides of the Zambezi are identical in appearance ; and it appears, therefore, that the river, if still existing at the time, did not form a barrier to their accumulation. Although the sands are at present always heavily bush-clad and firmly fixed in position, the hypothesis that they have been wind- borne under conditions different from those which now prevail agrees best with their general characters. I did not anywhere, however, see any dune-shaped masses — always the sand lay in broad smooth swells or bults, with gentle slopes leading to an even summit ; and the flatness of the sandy surface over wide tracts was very striking. The identity of these sands with the ' Kalahari Sand ' of Dr. Passarge has already been mentioned, and was indeed first recognized by that observer himself.1 His explanation of their origin is that they have been, in the first place, brought down by large rivers into the interior basin during a period of heavy rainfall ; and then partly redistributed by wind and other local agencies during a subsequent epoch of drought : and this idea finds no contradiction in any evidence that came under my own observation. Very little of the sand can have been derived from the basalts, in which the quartz- filled amygdules alone could supply this material ; so that, unless indeed the sand represents the destruction of supra-basaltic arena- ceous deposits of wide extent, for which there is little evidence, 1 'Die Kalahari ' 1904, pp. 541 & 561. Q.J.G.S. No. 2.50. p 202 MK. G. W. LAMPLTJGH ON THE [May 1907, it must have been transported into this region from without. Curiously enough, I saw comparatively little surface-sand in the sandstone -country around "Wankie, where there is an immediate source for the material ; but this district is so much dissected that loose detritus is likely to find its way rapidly into the stream-beds, whence it will be transported out of the sandstone-country to the Deka, and thence to the Zambezi. Dr. Passarge considers that the river-transport of the sands was mainly effected during a ' Pluvialzeit ' which was contemporaneous with the Glacial Period of our latitudes, and that their rearrange- ment took place during an ' Interpluvialzeit/ 1 Into these specu- lations I shall not venture to enter further than to state my impression that, whatever their earlier history may have been, the sands bordering the Batoka Gorge have reached their present position during a period of greater aridity and stronger winds 2 than now obtain in this region ; and that there has since been a time (?the Glacial Period) of much greater rainfall than the present, during which the sands became fixed, clad with vegetation, and in places deeply eroded by streams which have now disappeared. The reader who desires fuller information should peruse Dr. Passarge's great work, in which the Kalahari Sands, together with the other superficial deposits, are fully discussed in all their aspects. Surface-Limestone and Tufa. In the region traversed, calcareous deposits due to the evaporation of lime-charged waters are of common occurrence, but are usually of very limited extent and of recent origin. Owing to the interest excited in all the superficial deposits by Dr. Passarge's work, a short description of those which I observed seems, however, desirable. Surface-incrustations of this character border many of the dry stream-courses and shallow vleys, reminding me of a similar crust or ' caliche ' which I have seen under like conditions in Arizona. In the Batoka Gorge the great cliffs of basalt are frequently streaked vertically with greyish-white incrustations, due to lime and other minerals deposited by water oozing from small springs and evaporating in the torrid air of the chasm (see, for example, PL XI). These markings are frequently strung along a definite bedding-plane, but at the time of our visit all these places appeared to be absolutely dry. Indeed, I was everywhere impressed with the rarity or absence of true rock-springs, seeing that the strongly- jointed structure of the basalt and the deep trenching of the country by the gorges appeared to afford most favourable con- ditions for them. The springs that I saw were all due to the slow oozing of water from the loamy fiats, except a single one which I 1 f Die Kalahari ' 1904, chap, xxxvii. 2 I am informed by Mr. E. T. Coryndon that, in Northern Ehodesia, the winds at the present day are never strong enough to drift these sands, even if they were not sheltered by vegetation. I take this opportunity of also acknow- ledging my indebtedness to Mr. Coryndon for many useful items of information regarding the structure of the country beyond my traverse north of the Zambezi. Vol. 63.] GEOLOGY OF THE ZAMBEZI BASIN. 203 found issuing from the fault-rock low down in the eastern recess of The Chasm at the Victoria Falls. The temperature of this anomalous little fountain indicated that it was fed from the river above ; and although within the perpetually spray-drenched atmo- sphere of The Chasm, it had deposited a thick cushion of tufa, charmingly overgrown with moss and fern. Traces of a calcareous layer underlying the alluvial loam were noticed, in places, on the flats bordering both sides of the Zambezi above the Falls. It will be remembered that Livingstone found thick calcareous deposits in a higher part of the valley, and believed them to be the relics of a lake which was drained by the opening of the rift at the Palls.1 Besides the ' valley-calcretes,' I saw in a few places somewhat similar deposits of greater antiquity, that could not have been formed under existing conditions. These were generally associated with chalcedonic quartzite and with hard ferruginous material (' ferricrete '), which appeared in part to replace them and to represent a gradual alteration that is probably still in progress. Dr. Passarge has dealt very fully with the alteration (verkiesel- ung) of lime-rocks into quartzites in the Kalahari; and I think that this process must have taken place in the cases to which I refer. My best opportunity for examining material of this kind was near our camp at Makwa, just after we had crossed the Zambezi. Here the river, having emerged from the Batoka Gorge, has again expanded into a wide shallow stream, bordered by an irregular flat diversified with steep-sided basaltic kopjes of varying height. Two of these kopjes that I examined are capped by the deposits in question ; and I should probably have found the same conditions on other hills in the neighbourhood, if I had been able to reach them. The first kopje overlooks the right bank of the river close to our landing-place, and is the ' Logier Hill ' of Chapman and Baines, described by the former as being composed of 4 tufa, dipping eastward.' 2 On this hill I estimated the thickness of the superficial rock at about 20 feet, the material being partly siliceous and partly calcareous, but showing the same rugged cellular structure throughout the mass. A similar but thinner capping was observed on the second kopje, near our camp 1^ miles west-north- west of Logier Hill, which rose to about the same elevation and stood in like position with regard to the river. These hills are both much below the general level of the plateau, and must have received 1 ' Missionary Travels & Researches in South Africa ' 1857, chap, xxvi, p. 527. 2 ' Travels in the Interior of South Africa ' vol. ii (1868) p. 213. I was anxious to determine this site, so famous in the annals of African travel, where Baines and Chapman in 1862 made their unsuccessful attempt to build a boat in which to pass down the Zambezi. My ever-helpful pilot for the southern traverses, the late H. F. Greer, the Assistant Native Commissioner for the district, therefore called in some of the oldest natives to guide us to the place; and there, on the very spot, two of them told us how, as boys, they had come across the river to see the first white men in their country, — Grabimani (as they called Chapman) and his comrades — giving us a faithful narrative of the doings of these impressive strangers. r2 204 ME. G. W. LAMPLTTGH OK THE [May I907, their capping after erosion had already greatly lowered this par of the country. They are some 400 feet lower than the place already described (p. 199) on the rim of the Matetsi valley, 7 or 8 miles to the north-westward, where very similar surface-rocks were observed ; and we cannot therefore regard these surface-beds as forming part of a once-continuous sheet of ' Botletle-Schichten.' Moreover, I found the same kind of material to be plentiful at still lower levels, in the banks and dry bed of the Gongobujo River which drains eastward to the Zambezi on the northern side of Logier Hill. The sections in the banks of this stream, 2 to 3 miles above its mouth, showed much white ' calcrete ' and ' silcrete' — sometimes in soft sintery banks of 15 to 20 feet — along with masses of a hard splintery green rock, partly silicified (see Appendix I [F 1046, p. 211]), and some red jaspery streaks; and material of this kind was found to characterize the places where the gradient of the stream was low, being generally absent where the stream flowed steeply over the basalts. These deposits therefore sustain the conclusion previously stated^ that the surface-rocks have been formed on the flats at different stages in the lowering of the valleys, and that in this part of the country they do not mark any definite period. Some further details with regard to the surface-accumulations of the region will be found in Appendix III (p. 213). Lateritic Material. In places where the basalt is bare, or nearly so, the surface is sometimes littered with rough irregular lumps of ferruginous grit (; ferricrete '), due to the segregation of iron from the decomposing rock; but I did not light upon any place where this material formed masses comparable to those of siliceous and calcareous composition described above. The same segregative process is probably indicated by the occasional presence of thin cakes and narrow strings of iron-ore on the rock-surface and in joints and crevices of the basalt. I noticed these small iron-filled crevices in several places, particularly in a dry kloof on the ridge 5 or 6 miles north-east of Matetsi, where the ore had been dug by the natives and smelted in the adjacent forest, the relics of their old bloomeries still remaining. The pellety lateritic soil of the plateau has been previously described (p. 170). Fluviatile Deposits. The paucity of pebble-gravel along the bed of the Zambezi and its tributaries is remarkable. On the unbroken plateau this may be explained by the very low gradient of the streams; and in the rejuvenated valleys the force of the water is, perhaps, too great to allow such material to lodge. But it seems rather as if the basalt- blocks, when once broken into fragments, are soon completely disintegrated. Thus, within the Batoka Gorge, the river at low water is generally fringed on both sides by a forbidding border of Yol. 63.'] GEOLOGY OF THE ZAMBEZI BASES'. 1205 great; boulders only partly waterworn, interrupted here and there by miniature beaches of glaring-white quartz-sand, loudly ' musical ' when trodden on ; but the very scanty material intermediate in size between the boulders and the sand consists almost entirely of agate and chalcedonic pebbles derived from the amygdules. The same peculiarity is observable in the case of the smaller streams draining the basalt-country; so that neither in their present beds nor on the higher ledges which they have once occupied is there any noticeable accumulation of fluviatile detritus ; and even their flood-bars, like those of the Zambezi itself on its emergence from the great gorge, are built up of partly-worn basalt-blocks, occasionally faced with patches of white sand. In the north-eastern district, however, where the streams have derived part of their detritus from the older rocks (p. 172), medium- sized pebbles of these rocks and nut-like pebbles of pink quartz are abundant, not only in the present river-beds but also on low flats away from the streams, indicating a former drainage-system differing in detail from that of to-day. But even here the pebbles, where thickest, seem only to form a surface -layer, and I saw no instance of a gravel-terrace of construction such as one is accustomed to find in the home-country. I could not detect any of these extraneous pebbles on the flats of the Zambezi at Makwa, below the confluence of the above- mentioned streams ; but the abundant flakes of white mica con- tained in the river-sands at this place, and absent in the higher reaches, have no doubt been carried by these streams. I can therefore confirm Chapman's shrewd guess1 that this mica was brought down to the river from the north. The smoothly-worn basalt along the stream-beds, especially on the flood-platforms and other places slightly above ordinary water- level, is generally glazed with a thin black surface-film bearing a high polish, which gives no foothold and renders passage along the floors of the gorges very difficult. Glazing of this kind appears to be of very common occurrence on similarly-situated hard rocks in hot climates, and its origin has been frequently discussed. In Egypt, Mr. A. Lucas, who has carefully studied its occurrence at the Nile Cataracts, leans to the opinion that the film is deposited by water evaporating from the rock2; and my experience of the phenomenon in the Zambezi valley led me to the same opinion. I have elsewhere 3 remarked on the singular absence of recent animal-remains in the region, but the point will bear repetition. Prom the hunters' records we know how abundant formerly were the bigger mammals, including the elephant, rhinoceros, hippopotamus, buffalo, zebra, lion, etc., and indeed, though sadly diminished, they still inhabit the country. In the district south of the Batoka Gorge they were killed in great numbers during the last century; yet I failed to find anywhere either bone or tooth to 1 ' Travels in the Interior of South Africa ' vol. ii (1868) p. 213. 2 'The Blackened Bocks of the Nile Cataracts & of the Egyptian Deserts Govt. Bep. : Ministry of Finanee, Cairo, 1905. 3 Bep. Brit. Assoc. 1905 (South Africa) p. 299. 206 ME. G. W. LAMPLTJGH ON THE [May 1907, indicate the fact, despite my searches in the apparently favourable stream-beds and trenched loam-flats of the plateau. The African climate, aided perhaps by insect- and other low forms of life, appears to bring about the rapid disintegration of animal-remains, even of the hardest teeth.1 Supposing similar conditions to have prevailed in the past, it is easy to understand the deplorable lack of fossils in most of the African sedimentarv rocks. V. Summary and Conclusion. 1. The predominant feature in the geology of the Zambezi basin around the Batoka Gorge is the wide development of the Batoka Basalts, a great series of lava-flows of undetermined age, but pro- bably Mesozoic. These basalts stretch southward into the Kalahari Desert, and westward beyond the great bend of the Zambezi above the Liny an ti Flats ; but their extreme limits in these directions is not yet known. They are terminated northward by the emergence of the older rocks which form the Batoka upland. 2. The basalts are cut off on the east by the Deka Fault, which brings in the sandstones and shales ('Wankie Series') of the Wankie coalfield (= Matobola Beds, probably Permo-Carboniferous). This great dislocation, striking east-north-east where seen, is probably continued far to the north-eastward of the country examined, and constitutes a governing feature in the structure of the district. 3. The Wankie coal-measures rest directly upon the ancient schistose, metamorphic, and igneous rocks of Iihodesia ; and an equivalent series of sandstones, etc., probably occupies a similar position along the northern margin of the basalts. 4. Superficial material, principally unconsolidated red sand (' Kala- hari Sand ') and chalcedonic ' surface-quartzite,' overspreads large areas of the basaltic plateau, and denotes great changes of conditions in the central basin in late Tertiary and in Quaternary times. 5. The main element in the physiography of the country is the rejuvenation of the sluggish plateau-drainage, consequent upon the erosion of the Batoka Gorge by the Zambezi. The singularly zigzagging courses followed by the rejuvenated streams are due to certain structural characters of the basalts. It remains for me to render sincere acknowledgments for assistance rendered to me by many friends. To the Council of the British Association I am initially indebted for the opportunity of undertaking this pleasurable investigation in a new field. 1 That mammalian remains may, however, be preserved, under exceptional circumstances, is proved by the occurrence of calcareous bone-breccia in the ' Ehodesia Broken-Hill ' mining district in the ' hook ' of the Kafue Eiver (N.W. Ehodesia). The country-rock of this district, in places, is limestone. Specimens of this bone-breccia were obtained by Mr. A. Bromwich, of the British South Africa Company, during a recent visit to the locality, who kindly brought it to my notice. The much-desired recovery of specimens indicating the South African fauna antecedent to that of recent times is therefore not quite hopeless. Yol. 6s.~] geology oe the Zambezi basin. 207 To Sir Lewis Michell and to the officers of the British South Africa Company, both in Rhodesia and in London, my thanks are due for the liberal co-operation by which alone it was made possible for me to carry out the field-work in this wild region. To Mr. F. "W. Sykes, until recently the District Commissioner and Conservator at the Victoria Falls, who organized and led our expedition on the northern side of the Gorge, I owe more than can be expressed in this simple acknowledgment. It is impossible within the allotted limits of space to particularize at length the assistance that I received on all sides in Rhodesia ; to some of which I have, however, been able to make reference in the text of this paper. But my appreciation of the kindness shown to me is none the less keen if unexpressed. I have to thank Mr. F. W. Sykes, and Miss Louisa Rhodes (acting as the representative of her brother, the late Col. F. "W. Rhodes, who accompanied us on our journey north of the Gorge), for the photographs with which this paper is illustrated. The collection of rock-specimens made during the investigation has been handed over to the Petrographical Department of the Geological Survey of Great Britain, for preservation at the office in tfermyn Street, London. Appendix I. Petkographical Notes, by H. H. Thomas. The Dolerites. Intrusive ophitic olivine-dolerites. F 1032 & 1035. Localities: 10 yards from fault at Jack's (Mtoro's) Kraal, Deka Valley ; and 30 yards from fault, Eondulu, Wankie. Of the specimens examined, two rocks seem to possess undoubted intrusive characters ; in the hand-specimen they present a fairly compact appearance, without any conspicuous porphyritic mineral. The fresh rock is greenish-brown in colour, with small dark- green patches; and F 1082 showed a few minute amygdaloidal cavities, filled with zeolites, chlorite, and secondary quartz. Under the microscope these rocks prove to be almost holocrys- talline ophitic olivine-dolerites, of somewhat unusual type. They consist of magnetite, plagioclase with a little orthoclase, and augite. The magnetite is for the most part the earliest product of con- solidation and builds well-formed octahedra, but also occurs in strings and patches. The olivine exists as small idiomorphic crystals, slightly elongated, parallel to the edge (100) (010), and as rounded grains. No fresh olivine now remains, but that it was a variety fairly rich in iron is indicated by the border of iron-ores fringing the pseudomorph. The pseudomorphs are composed of a fibrous highly-refracting mineral, with straight extinction and a yellow to yellow-brown colour, recalling the ' Potluck ' pseudomorphs of the Derbyshire ' toadstones ' or those of some of the Tertiary dolerite- sills of Skye. 208 MB,. H. H. THOMAS ON THE [May I907, The felspars, which are practically all of one generation, build lath-shaped crystals ranging up to 1*2 mm. in length. Generally they are twinned according to the Carlsbad law alone, but a few show albite-lamellation. The low and sometimes almost straight extinction of these crystals indicates an acid plagioclase, approxi- mating to if not actually reaching oligoclase. The augite, which is a pale variety, but not quite colourless in section, forms plates ophitically enclosing the plagioclase-laths. The orthoclase occurs as small untwinned patches, filling the spaces between the earlier- formed crystals, and was evidently the last product of consolidation. A few small needles of apatite may be seen, but the mineral is rare ; and chlorite occurs as a decomposition-product of the ferromagnesian minerals. Small chloritic patches might possibly represent residual glass, but proof is wanting. Both these rocks were completely devoid of flow-structure. In the apparent high percentage of alkalies these dolerites approximate in composition to the mugearites of Harker, but differ strongly from them in a greater percentage of the bisilicates and in the paucity of apatite. The Flows. These rocks may be divided into two types : — (a) Those in which the augite is mostly granulitic, but which also contains larger subophitic plates. (b) Those in which all the augite is granulitic in character. (a) The Subophitic Dolerites. F 1019. Locality : Creek at Mamba Camp, north of the Zambezi. 1028. Locality : Bed ofLukunguli(Jambezi), near Dambi's; (bedded). 1029. Locality: First crossing of the Lukunguli from Tsheza's. 1030. Locality : Matetsi River, south of Matetsi Station. In the hand-specimen the above rocks are of a dark-grey colour, one alone (1028) having a dull-red tinge. They are heavy and compact, and show bright felspar-crystals. They are typically non- amygdaloidal. Specimens 1019 & 1029 show a platy structure, apparently parallel to the surface of the mass ; while 1030, on a weathered surface, shows light- coloured circular patches about a quarter to three-eighths of an inch in diameter, the origin of which is obscure unless it be a greater percentage of felspar in that area. The rocks consist of magnetite, augite, and plagioclase-felspar, with olivine and apatite as accessories. The texture is fine-grained and there is no flow-structure. The magnetite builds octahedra, but occurs also in irregular patches and strings. The augite, which is pale in colour, occurs in two forms, either as plates wrapping round but seldom enclosing the felspar, or as knots or small crystals without good outline in the groundmass. These rocks may be said to be rich in augite, but this is compen- sated in a measure by the almost complete absence of olivine ; only Vol. 67,.'] PETROGRAPHY OF THE ZAMBEZI BASIN. 209 in two specimens (1028 & 1030) were doubtful pseudomorphs after this mineral detected. The granules of augite are often twinned, and elongated parallel to the twin-plane. The felspars occur in two generations, but are seemingly very similar in composition, both being just on the acid side of typical labradorite. The earlier generation builds porphyritic slightly- zoned crystals, usually twinned according to the Carlsbad and albite-laws, but occasionally showing pericline-lamellse. The sym- metrical extinctions on the twin-plane range up to 36°. The micro- liths are extremely slender, usually twinned on the Carlsbad plan only. Apatite occurs sparingly, and there seems to have been a small residue of interstitial glassy material. It is quite probable that some of these rocks may be sills ; but, apart from field-evidence, there is no reason for removing them from those considered as true flows. (b) The Granulitic Dolerites. F 1016. Locality: Railway-cutting at west side of bridge, Victoria Falls. 1017. Locality : Bottom of the Zambezi Gorge at the entrance to the Songwi. 1020. Locality: Lower cataract at the Tshimamba. 1021. Locality : Upper cataract at the Tshimamba. 1022. Locality : South side of the Zambezi, floor of the gorge near the Namaruba confluence. 1024. Locality : Bwani River, north of the Zambezi. 1025. Locality: Bwani River, north of Makwa (platy beds). 1026. Locality : Bwani River, north of the Zambezi (platy beds). 1033. Locality: Kopje near the railway-bridge, 6 miles west of Wankie. 1037. Locality: Rock in the fault, Deka River, kopje near the railway-bridge. The fresh rocks, such as 1016, 1020, 1031, 1033, are compact, and dark-grey to grey-brown in colour, weathering brownish or greenish according to the extent to which oxidation or chloritiza- tion has proceeded. They are feebly vesicular : in P 1024 cavities reach half an inch in diameter ; in other specimens they are smaller, while in some they are absent. Alineralogically they are identical with the rocks containing subophitic augite, and the two groups undoubtedly pass one into the other. F 1017 represents an inter- mediate stage, in which there are occasional bigger crystals or knots of augite. The felspars occur in two generations, as before ; but the micro- liths often tend to take up a parallel arrangement indicative of flow, although flow- structures are generally ill-defined or absent. In composition and dimensions the felspars agree with those described above. Magnetite is comparatively abundant in octahedra, but by no means constant in its percentage. In texture these rocks are all fine-grained, some more so than others. Olivine is rare and in many cases absent, while the augite, where it exists as large crystals, has undergone partial re-absorption. 210 MR. H. H. THOMAS ON THE [M"ay I907, The vesicles are usually rilled by zeolites, but sometimes by secondary quartz and also chlorite. Some of the flows are much decomposed, and occasional specimens, such as F 1037, show a mass of felted felspar-microliths silicified and highly iron-stained. Unusual Types. F 1034. Locality: Near the fault, Deka Eiver, near the railway-bridge. This rock in the hand-specimen shows large porphyritic felspars set in a red, highly ferruginous ground-mass, which is apparently wholly crystalline. Under the microscope the porphyritic felspars are seen to be twinned according to the Carlsbad and albite-laws, and to belong to a species of labradorite. The groundmass con- tains olivine now converted into yellow pseudomorphs, sometimes showing the original crystal-outline. Augite occurs in small, mostly idiomorphic crystals, and also plentifully in the groundmass. The felspar-microliths are labradorite : they are much twinned (Carlsbad and albite-laws) and lack any definite arrangement. There is a good deal of interstitial material which was originally glass, now rendered absolutely opaque by limonitic iron-ores. The rock, as a whole, is slightly vesicular ; the vesicles, which range up to half an inch in diameter, are filled with stilbite and lined with chlorite. Locally it shows signs of brecciation, and from this and other properties it is suggested that it is the margin of an intrusion or flow. , F 1031. Locality: 2 miles south of 'Klaas's, near the head of the Matetsi. A remarkably fresh-looking, dark greyish-brown rock, in which light amber-coloured grains and crystals are very noticeable. Under the microscope it is seen to ally itself to the subophitic or glomeroporphyritic examples described above, but to differ in the occurrence of an abundance of a bright-yellow mineral of secondary origin. This mineral, which is fibrous and strongly refracting, both replaces small crystals and grains of olivine and fills minute cavities. In all other respects this rock may be grouped with the sub- ophitic varieties already described. Fragmental Rocks, etc. F 1018. Locality : Eastern bank of Mavangu Creek, near Camp. 1023. Locality : South side of the Zambezi, floor of the gorge near the Namaruba confluence. 1027. Locality : Bwani River, north of the Zambezi. Among the fragmental rocks one true tuff was noticed, namely F 1018. It consisted of broken felspars, almost opaque reddish tachylytic glass, angular and vesicular masses of fine-grained dolerite, set in a matrix of fine broken felspar-microliths and clastic quartz. The other specimens are apparently flow-breccias : they are largely made up of fragments of tachylytic glass as before* Yol. 6^.~] PETROGRAPHY OF THE ZAMBEZI BASIX. 211 but these are cemented by doleritic material which is of the nature of a flow and not fragmental. Zeolites. The zeolites collected separately include stilbite, mesolite, and laumontite (?). Stilbite and laumontite (?) are associated in the same mass, the stilbite being pinkish and the supposed laumontite opaque - white. The mesolite occurs in colourless, translucent, radiating masses. The Sediments, etc. Boomka Flags. F 1038. Locality: Sandstone, 6 miles north of Geise's, Deka valley. A fine-grained quartzose sediment, iron-stained, and made up of very angular grains measuring not more than 0-15 millimetre in greatest dimension ; certainly not wind-blown. Surf ace -Deposits. F 1044. Locality: Limestone, 10 miles north of Deka valley at Geise's. This rock is yellowish-grey, compact, and fine-grained, with white patches and streaks. Under the microscope the main mass of the rock is seen to be composed of a calcareous paste which has under- gone little or no silicification, and a few small patches of recrystal- lized calcite. The white patches are seen to consist of well-rounded quartz-grains, with some equally well-rounded limestone-grains set in a fine detrital calcareous cement. The limestone is probably of organic origin, and contains many sections of organic remains which may be referred to Cyprids. It is suggested that the streaks and patches are solution- tubes and cavities filled with blown sand. F 1045. Locality : East of Mavangu Camp, north of the Zambezi. A pink quartzite, made up of millet-seed grains of quartz and microcline, with a little finer material of subangular character. The matrix is chalcedonic. The large proportion of microcline would seem to indicate derivation from an area of crystalline schists and gneisses. Probably this is a desert-sand solidified by secondary silicification. F 1046. Locality : Bed of the Gongobujo Eiver, Makwa. Greenish-grey siliceous rock, with white calcareous patches. It is similar to the above, with the exception that it is not red-stained and contains a less quantity of microcline. The matrix between the grains is chalcedonic, but in this case evidently replaces an original calcareous cement. In the white patches the replacement of the calcareous material has gone on to a very small extent. The white patches seem, therefore, to represent more or less the original character of the rock. Pebbles from the Gwemanzi River, north of the Zambezi, include several schists and gneisses, among which may be mentioned a quartz-biotite-gneiss and a garnetiferous pegmatite- gneiss. Appendix IT. — Local Notes on the Batoka Basalts. Locality. Predominant Characters. Dip, when seen. Joints, etc. Northern Side of the Zambezi, and Batoka Gorge. Victoria Falls Three slightly amygdaloidal massive beds, with two amyg- (Slight) S.E. or S.S.E. E. 10° S., cut at low angle by Chasm- daloidal breccias at ry.-bridge. fracture (see p. 188). Gorge at Songwi Massive amygdaloid, with seve- ral bands of breccia, some thick. S. 20° E. at 3° to 5°. E.; to E. 20° N. Moravu, 6 miles east of Dense, slightly amygdaloidal ; E. to S.E. E. 25° N. Songwi. platy structure. Mavangu, between Camp Dense platy basalt, with thin Variable ; N.E., 1 Obscure & irregular: and Gorge. tuff-like breccia (see p. 184). W., & W. 20° S. S. & S. 10° E. Gorge south-east of Ma- Several thick massive bands, Apparently W. Strong. vangu Camp. with soft greenish-grey inter- calations. Amygdaloidal basalt, with at 2°. Mamba Creek, near Camp. Rolling, but Irregular, chiefly ' pillow '-structure, and in mainly S.E. E. 10° S. places platy ; with red spongy breccia below. Gorge at the Tshimamba Dense platy basalt ; with inter- S. at 5° to 15°. Mainly E. Cataracts. vening breccia in lenticular - masses. Kalonga's Cleft, Amygdaloidal basalt, hard and W. at 3° to 5°. E. & a few S. ; also Karamba River. splintery ; with a band of red many ' shatter- breccia about 60 feet thick. planes ' with Lower (south-eastern) Basalt and breccias. Apparently S. veining. Strong S.E. reach of the Karamba River. Kalomo River,near Camp. Dense. Indefinite. Irregular ; some S. 20° E. Gorge near the Namaruba Massive basalt, with amyg- S. at 8°. E. 10° N., & others confluence. daloidal bands and breccia. S. 10° E. Gwemanzi River, near Dense, platy. N.E. Master-joints E. ; Camp. others S.E. Bwani River Purple amygdaloidal basalt, and Rolling, mainly Some E. ; others greenish basalt with shaly S.E., up to 15°. S. 30° E. structure. Southern Side of the Zambezi. Zambezi shore at Makwa. Platy amygdaloidal basalt and Apparently flat. Irregular; E. 35° N. spongy breccias. & S. 30° W. Matetsi River, near the Dense basalt and slaggy amyg- ? E.,with calcite-veins. Zambezi confluence. daloid, confusedly mingled. Lukunguli River, first crossing. Lukunguli River, above Dense greyish basalt. ? Dominant, E. 20° S. Purple porphyritic rock, with S.W. at 10°. E. 20° N. Dambi's Kraal. regular platy structure re- sembling bedding. Matetsi River, 1 mile Dense greyish basalt with sphe- Not seen (but 2 Dominant, E., but above the railway- rules (glomeroporphyritic) ; miles higher up- rather confused. bridge. and purple basalt with chal- stream, rolling & cedonic & zeolitic amygdules. mainly E.) Matetsi River, near head, Dense, slightly amygdaloidal. Ground flat: dip Obscure ; some 8 miles from Pandama- not seen. S. 30° W. tenka. 2 miles W. of Matheison's. Dense, platy. S.S.E. Stream south of Deka ... Amygdaloidal basalt, with spheruloid structure. Not observable. Deka River, 2 miles below Platy, with spheruloid struc- S.W. or W., but Deka. ture, and amygdaloidal. rolling. Deka valley, 10 miles Do. Do. E., with calcite- and below Deka. haematite- veins. Same General Features Continue to 'Mtoro's. Deka valley, between 1 Dense, amygdaloidal. E., with veins. 'Mtoro's and 'Ngoni's. I 1 Vol. 63.-] THE GEOLOGY OF THE ZAMBEZI BASIN". 213 Appendix III. Notes on the Supebeictal Deposits along the Routes masked on the map (pi. xvii). Locality. Charade)- of the Surface traversed. Northern Side of the Zambezi. Victoria Falls to the Songwij River. Songwi River to Mavangu Mavangu toTshimamba ... Tshimamba to Kalonga's Cleft. ; Kalonga's to the Kalomo River. Kalomo River to the Gwemanzi River. Gwemanzi to 'Ntoro 'Ntoro to Makwa Stony flat, a former bed of the Zambezi, cut by- gullies ; "with spriukling of gravelly chalcedonic detritus. First, alternations of stony lateritic ground with grassy flats of thiu loam : then, a sand-bult at the head of small streams draining to the Zambezi. Continuation of the sand-bult, with loose blocks of 'silcrete' (surface-quartzite) in patches along the edge ; then broken basaltic country, with lateritic soil. Rugged dissected basalt-country, with some heavily grassed stretches of loam along diy stream-beds on the plateau. Very rugged basalt-country : huge bars, up to 12 feet high, of basalt-boulders, in the bed of the Kalomo, with a sprinkling of pebbles and mica- flakes from the Fundamental Complex. Smoother and less broken plateau beyond the Kalomo basin, with shallow valleys containing much detritus of the ancient rocks, etc. (see p. 172). A patch of ' silcrete ' on the flat east of the Namaruba River, and traces of high-level gravel. Slightly -broken basalt-plateau, "with scattered blocks of ' silcrete ' and some pinkish quartz-pebbles, but little or no detritus of ancient rocks in the streams. Descent from the plateau over basalt, with sprink- ling of granitic, etc. gravel in places, and patches of ' calcrete ' on the lower ground : tract of red sand on the slope leading to the Zambezi. Southern Side of the Zambezi. Makwa to the Matetsi River ...] Matetsi valley, from Tsheza's to the confluence with the, Zambezi. Matetsi River (Tsheza's) to the; Lukunguli River (Sianteti's) Sianteti's to the Batoka Gorge Sianteti's to Dambi's (Lukun- guli valley). Dambi's, to the head of the Lu- kunguli valley, and across the water - parting to Matetsi Station. Sloping bult of red sand, covering a ridge, with 'silcrete,' ' calcrete,' etc. at the edge (see p. 199). Broad valley with steep sides; several terraces of dark alluvial loam in the bottom, the lowest con- taining manjr freshwater shells 1 ; broad delta of basalt-boulders at the confluence. Blocks of ' silici-calcrete ' abundant on the basalt- spurs of the Matetsi valley, and a patch about 15 feet thick on the crest, at the margin of the plateau. Upland flats of thin loam thickly grassed, breaking away into stony basaltic valleys. Some mottled red sandstone and ' silcrete ' at the margin of a thinly sand-covered tract. Basaltic upland, with lateritic soil and gravelly ' ferricrete,' 'silcrete,' and loam in places, be- coming very rugged towards the Batoka Gorge. Ferruginous and chalcedonic gravel on a high terrace in the valley : stony slopes on the south, leading to a plateau of the usual type — alternately stonjr and loamy — ; but westward, grassy loam-flats expand into a wide basin, edged on the north and south by sand-bults. Loamy flats, edged by rocky ground and partly surrounded by sand-bults ; some ' ferricrete ' and ' silcrete ' along the edge of the sands : also cakes and veins of iron-ore at the top of the basalt in places. See list in Rep. Brit, Assoc. 1905 (South Africa) p. 301. 214 ME. G. W. LAMPLUGH ON THE [May 1907, Locality. Character of the Surface traversed. Matetsi Station to Lukubiro's (Matetsi and Tshitshigumba valleys). Lukubiro's to Matbeison's (head of the Matetsi basin). Matheison's to Deka (head o£ the Deka basin) Deka to 'Ngoni's (southern edge of the Deka valley). Narrow sand-bult in the angle between the rivers, indurated to a soft red rock at the base; but chiefly loam-flats, with stony lateritic tracts in the valleys. Succession of broad grassy flats of black loam, up to 9 feet deep, interspersed with low rises of basalt with thin lateritic soil : a thin patch of 'calcrete' on the north side of the Matetsi River where crossed. Broad sand-bult, rising 200 to 300 feet (Boomka of Chapman), between the basins of the Matetsi and Deka, with some patches of flaggy sandstone at the edge (see p. 196) ; but country otherwise as last. Grassy loam-flats and stony basalt-country inter- spersed, the latter thickly sprinkled in places with small pebbles and rough lumps of quartz, quartzite, chalcedonjr, and sandstone : also some sand-veld in approaching 'Mtoro's. EXPLANATION OF PLATES X-XVII. Plate X. Rift, about 80 feet deep, in Cataract Island, Victoria Falls, excavated along a vertical joint or small fault in the Batoka Basalts by an overflow streamlet. The ' Leaping Water ' is seen in the distance. Plate XL The Batoka Gorge, looking up from the confluence of the Songwi Eiver, about 6 miles below the Victoria Falls. A sand-bult forms the sky-line on the left. Plate XII. The Batoka Gorge at Syakowi, near the confluence of the Mavangu stream, looking down, about 17 miles E.S.E. of the Victoria Falls. Plate XIII. The Batoka Gorge, about 25 miles E.S.E. of the Victoria Falls, immediately below the Tshimamba Cataracts looking N.E., down stream (see plan, fig. 5, p. 189) ; showing the flood-platform with islands, and the development of zigzags along joints in the low-water channel. Plate XIV. The Batoka Gorge at the confluence of the Karamba River (see fig 6, p. 190) about 35 miles east of the Victoria Falls, looking west, up-stream ; depth of gorge = about 750 feet. Plate XV. Kalonga's Cleft, nearly 300 feet deep, at, the head of the gorge of the Karamba River, a tributary of the Zambezi (see figs. 6, 7, & 8, pp. 190-191). Plate XVI. The Batoka Gorge at the sharp bends just below the confluence of the Songwi River ; showing promontories (' knife-edges ') partly destroyed by Aveatbering, and a lower pinnacle (in the middle of the picture) cut off by an ancient channel of the river. Plate XVII. Geological sketch-map of the country around the Batoka Gorge of the Zambezi, on the scale of 10 miles to the inch ; and three diagrammatic sections : (1) across the Zambezi basin ; (2) across the lower portion of theWankie Series at Wankie; and (3) in theWankie Series adjacent to the Deka Fault. Quart. Journ. Geol. Soc. Vol. LXIII, PI. X. *■ a MM ■ !■ n - M -1 Photo by the late Col. F. W. Rhodes. Rift, about 80 feet deep, in Cataract Island, Victoria Falls, excavated along a vertical joint or small fault in the Batoka Basalts by an overflow streamlet. The 'Leaping "Water,' in the distance . The joint-plane showed traces of slickensides. Quart. Journ Geol. Soc. Vol. LXIII, PI. XI. Photo, by Sykes. The Batoka Gorge, looking up from the confluence of the Songwi River, about 6 miles below the Victoria Falls. A sand-bult forms the sky-line on the left. Note the sharp trenching of the plateau; and compare the angle of slope of the walls, here nearly 500 feet high, with that shown in the next three Plates. Quart. Journ. Geol. Soc. Vol. LXIII, PI. XII. Photo, by F. W. Sykes. The Batoka Gorge at Syakowi, near the confluence of the Mavangu stream, looking down, about 17 miles E.S.E. of Victoria Falls. Note the dip of the basalts in the distant cliff; also, the diminished angle of slope compared with that shown in PL XI. Quart. Journ. Geol. Soc. Vol. LXIII, PI. XIII. Photo, by F. W. Sykcs. The Batoka Gorge, about 25 miles E.S.E. of Victoria Falls, immediately below the Tshimamba Cataracts, looking N.E., down-stream {see plan, Fig. 5) ; showing the flood- platform with islands, and the development of zigzags along joints in the low- water channel. Note the prolongation of the middle reach into an inlet on the right bank, and the escape of the river from it at right angles. The white patch in the foreground is a little beach of quartz-sand. The depth of the gorge here is about 600 feet. Quart. Journ. Geol. Soc. Vol. LXIII, PL XIV Photo, by F. W. Sykes The Batoka Gorge at the confluence of the Karamba River {see Fig. 6) about 35 miles east of Victoria Falls, looking west, up-stream; depth of gorge, about 750 feet. Compare the angle of slope with that in the preceding Plates ; and note the close- set joints of the basalt in the foreground. Quart. Jourri. Geo!. Soc. Vol. LXIII, PI. XV Photo, by F. W. Sykcs. Kalonga's Cleft, nearly 300 feet deep, at the head of the gorge of the Karamba Elver, a tributary of the Zambezi {see Figs. 6, 7, and 8). The stream enters the Cleft on the right, after dropping from the plateau into a shorter chasm branching off from this at right angles. Quart. Journ. Geol. Soc. Vol. LXIII, PL XVI. Photo, by the late Col. F. W. Rhodes. The Batoka Gorge at the sharp bends just below the confluence of the Songwi River; showing promontories ('knife-edges') partly destroyed by weathering, and a lower pinnacle (in the middle of the picture) cut off by an ancient channel of the river. ol. LXIII, PI. XVII. Quart. Journ. Geol. Soc. Vol. LXIII, PI. XVII. GEOLOGICAL SKETCH-MAP OF THE COUNTRY AROUND THE BATOKA GORGE OF THE ZAMBEZI. | 5" I' '"' ;s tf: t* < iim 1 1 s i a Fundamental Complex / INCH = 10 MILES. 2.-DIAGRAMMATIC SECTION ACROSS THE LOWER PORTION OF THE WANKIE SERIES AT WANKIE, — — ^S*" ■ yd. 63.^ geology of the zambezi basin. 215 Discussion. The President, in returning the thanks of the Society for the interesting and luminous contribution to our knowledge of African geology and physiography made by the Author of the paper, referred to the earliest information regarding the region which was obtained by Livingstone, and to the prevalent opinion at the time that the striking gorge of the Zambezi is due to a vast rent in the crust of the earth. It was satisfactory to him to find the suggestion con- firmed which he then made, nearly half a century ago, that even the ravine of this African river is no exception to the rule that such topographical features are due to river-erosion. The details furnished by the Author from his own personal survey of the ground were of great value, in showing how rock-structures had modified the progress of the erosion and would give rise to future important changes in the course of the river and the excavation of its caiion. The similarity of geological conditions and of the resultant topo- graphy between the basalt-plateau and gorge of the Zambezi, and the lava-fields and canons of the Snake River in Western America, was remarkable. If the Author had succeeded, during his short sojourn in the country, in gleaning such an amount of new and important facts, it was to be expected that a still ampler harvest awaited more prolonged and exhaustive investigation. As a piece of pioneer-work, his paper was an admirable example of how much could be achieved in a short time by a trained eye and an experienced judgment. It would form a memorable feature in the history of African geo- logical exploration, and meantime was heartily appreciated by the Society. Dr. Hatch said that, during his visit to Rhodesia in 1894, he did not get as far north as the Zambezi River, and therefore he could not speak from any personal knowledge of the district so admirably described by the Author ; but he had made some study of the volcanic rocks of other parts of South Africa, and the Author's paper appeared to the speaker to have an important bearing upon these. His description of the Batoka Basalts, especially of the amygdaloidal bands that occur in the upper part of the flows, with their vesicular cavities infilled with agate, green-coated chalcedony, quartz, and zeolites, recalled exactly the character of the Bushveld Amygdaloid, which covers a large area of the Transvaal immediately north of Pretoria, namely, the well-known Springbok Flats. The work of the Transvaal Geological Survey had shown that these lavas overlie sandstones which are considered to be of Karroo age and younger than the Permo-Carboniferous coal-measures of the Transvaal. The Author stated that the Batoka Basalts are younger than the Wankie coal-measures or Matobola Beds, which Mr. Molyneux also considered to be of Permo-Carboniferous age. Again, there was a remarkable resemblance in petrographical habit between the Bushveld Amygdaloid and the lavas of the Volcanic Group of the Drakensberg and the Malutiberg, especially in the occurrence of the long drawn-out vesicles which had originated the name of 216 THE GEOLOGY OF THE ZAMBEZI BASIN. [May I907, 'pipe-amygdaloid/ It was interesting to note that the Author also referred to the occurrence of a ' pipe-amygdaloid ' in the Batoka Basalts. The Yolcanic Group of the Drakensberg was classified by South African geologists, following Dunn, as the uppermost division of the Stormberg Beds, and consequently as younger than the Permo-Carboniferous coal-beds of Cape Colony. Considering the vast extent of the plateau-basalts of North America and of the Deccan in India, geologists would admit the possibility that in South Africa these great basaltic flows of Rhodesia, the Transvaal, and the Cape Colony may have had a common genetic origin, and were erupted towards the close of the Stormberg Period. There appear to have been three chief epochs in the geological history of South Africa, when volcanic activity took the form of a vast extrusion of lava. The first followed the close of the Witwatersrand Period, producing the lavas, accompanied by breccias and tuffs, of the Yentersdorp Volcanic System. The second followed the deposition of the Pretoria Beds, producing the acid felsites of the so-called ' red granite '-formation of the Transvaal; while the third took place towards the close of the Karroo Period, producing the basic lavas of the Stormberg, the Springbok Plats, and (as it would appear) the Batoka Basalts. The Author expressed, in reply, his thanks for the reception accorded to his paper. YoL 6t>.'] SILURIAN INLIER IN THE EASTERN MENDIPS. 217 13. A Silurian Inlier in the Eastern Mendips. By Prof. Sidney Hugh Reynolds, M.A., P.G.S. (Read March 13th, 1907.) [Plate XVIII —Microscope-Sections.] Contents. Page I. Introduction 217 II. Description of the Exposures 219 (1) The Lava or Trap. (2) The normal Tuffs and the associated Fossiliferous Eocks. (3) The Coarse Ashy Conglomerate. III. The Petrographical Characters of the Eocks 230 (1) The Lava or Trap. (2) The normal Tuffs. (3) The Coarse Ashy Conglomerate. TV. The Mutual Eelations and Nature of the Eocks 234 V. Summary and Conclusions 238 I. Introduction. The Mendip Hills consist of four periclinal upfolds of Carboniferous Limestone, arranged en echelon from north-west to south-east. Each pericline includes a core of Old Red Sandstone, and the south-eastern or Beacon-Hill pericline further shows a series of igneous rocks. It is with these that the present paper deals. The existence of igneous rocks in the Eastern Mendips was first noted by Charles Moore,1 who described them as ' a basaltic dyke of considerable thickness emerging from beneath the Old Eed Sandstone at East End near Stoke Lane.' He considered that, from the general physical character of the Mendips, it was not improbable that the dyke might be co-exten- sive with their range. He not only attributed the upheaval of the whole Mendip range to the intrusion of this igneous mass, but also considered that it was responsible for the remarkable inverted character of the Carboniferous beds at Luckington, where the Coal-Measures are worked under the Carboniferous Limestone. John Morris 2 refers to the rock at Stoke Lane, as ' ' a dyke of considerable thickness, emerging from beneath the Old Eed Sand- stone, occurring as bosses in the field, but, traced for some distance over the district, it is conglomeratic in places, and pronounced by Mr. D. Forbes to be dolerite.' The igneous rocks are not shown in Sanders's map of the Bristol Coalfield (published in 1864), but appear in the map of the Geological Survey (1884) as a series of isolated patches ex- tending from Downhead on the east, to Beacon Plantation, south- west of Stoke Lane, on the west, a distance of about 3 miles. 1 Quart. Journ. Geol. Soc. vol. xxiii (1867) pp. 451-52. 2 Geol. Mag. vol. v (1868) p. 236. Q. J. G. S. No. 250. q 218 PEOF. S. H. REYNOLDS ON A SILURIAN [May I907, The field-exposures were mapped by the officers of the Geological Survey, Messrs. H. Bristow, W. A. E. Ussher, & H. B. Woodward ; and, as mentioned in the Survey-memoir,1 Mr. Ussher considered the exposures to be parts of one continuous mass, while Messrs. Bristow & Woodward considered that they occurred as bosses or hummocks in the manner represented in the Survey-map. A diagrammatic section by Mr. Ussher is given,2 which shows the igneous rock as a dyke breaking across the Old Eed Sandstone, and spreading out near the surface of the ground. The Old Red Sandstone is represented as considerably disturbed. Sir Archibald Geikie and Dr. A. Strahan,3 in their account of the igneous rocks associated with the Carboniferous Series of the Bristol District, briefly describe the rocks in question as follows : — * A group of masses of igneous rock is shown on the Geological- Survey map (Sheet 19) rising along the ridge of Old Eed Sandstone to the north of Shepton Mallet. These masses were also visited by the Director-General and Mr. Strahan, with the view of ascertaining whether they formed part of the Volcanic Series which has now been described.4 But they were found to belong to a different petrographical series. Thin slices prepared from the freshest of the rocks in Moon's-Hill Quarry and from Beacon Hill have been examined by Mr. Teall, who finds that they are undoubted andesites. They appear to rise intrusively through the (Upper) Old Bed Sandstone. They have none of the characters of true lavas, nor do they seem to have any accompaniment of tuff or agglomerate. Their age must remain undecided. They are presumably younger than the Old Bed Sandstone, which in their immediate neighbourhood passes conformably upward into the shales and limestones at the base of the Carboniferous system. They may possibly belong to the Carboniferous volcanic series. Their more acid character than that of the lavas of Weston, Middle Hope, and Goblin Combe would not be a valid objection to such a relationship, for the intrusive sheets and bosses of the Carboniferous series in the South of Scotland and in Ireland are often much less basic than the contemporaneous lavas. This question, however, must remain until the district is surveyed in more detail.' Hitherto all geologists have agreed in regarding the rocks as intrusive ; but, during the last few years, the opening of several new quarries pointed to the desirability of remapping the exposures. This was done with more interesting results than might have been anticipated, as it showed that the trap-rocks were associated with an extensive series of tuffs, some of which contained Silurian fossils. The mutual relations of the different rocks were, however, very difficult to ascertain, as much of the mapping was based on material thrown out by moles and rabbits. For the further elucidation of the geology of the district a Committee of the British Association was appointed at the recent meeting (1906) at York ; and, under the auspices of the Committee, a series of 1 ' Geology of East Somerset & the Bristol Coalfields ' Mem. Geol. Surv. 1876, p. 14. 2 Ibid. p. 15. 3 ' Summary of Progress of the Geological Survey for 1898 ' (1899) pp. 110-11. 4 Namely, that associated with the Carboniferous rocks of Northern Somerset. Vol. 6$.^ INLIER IN THE EASTERN MENDIPS. 219 seven trenches was dug, from which a considerable amount of information embodied in the following pages was obtained.1 II. Description of the Exposures. (1) The Lava or Trap. In the Geological Survey-map, on the scale of 1 mile to the inch, the trap is shown as forming three principal masses : — (1) A western mass extending westwards from the road between Stoke Lane and Waterlip to the neighbourhood of Knapp's Farm, with a detached portion still farther west on Beacon Hill. This may be called the Sunnyhill and Beacon-Hill mass. (2) A central mass, with a nearly square outcrop, lying immediately east of the Stoke Lane-and-Waterlip Road. This may be called the Moon's-Hill mass. (3) An eastern mass, the eastern extremity of which commences near Downhead, stretching in a westerly direction almost parallel to the main Frome Road for about a mile ; this may be called the Downhead and Tad hi 11 mass. Small isolated patches are also mapped on the southern border of the Sunnyhill and Beacon-Hill mass. For purposes of description the foregoing arrangement may be retained, although it is probable that the Moon's-Hill mass is continuous with the Sunnyhill and Beacon-Hill mass. As has been already mentioned, much of the mapping is based on material thrown out by moles and rabbits, and it is sometimes a matter of difficulty to decide whether the material has been derived from the weathering of solid trap or of trap-blocks in the coarse ashy conglomerate. When tuff-debris is mingled with the trap, the rock is mapped as coarse ashy conglomerate ; when trap-debris occurs alone, trap is mapped. The Sunnyhill and Beacon-Hill mass. — The westernmost region where trap-debris uumingled with tuff was found, was in the fields lying in the angle between the Wells-and-Frome Road and the Beacon-Farm Road, much debris having been thrown out in fixing a new fence. Farther east, at a point 350 yards west of the ' Waggon & Horses ' Inn, large blocks of trap occur in some shallow gorse-grown depressions close to the Boman Road. These depressions appear to represent old trial-workings, and from them 1 I have had the advantage of going over many of the exposures with two members of the British-Association Committee, Prof. C. Lloyd Morgan and the Rev. H. H. Winwood, also with Dr. A. Strahan, Mr. F. R. Cowper Reed, and Mr. E. E. L. Dixon. To all these gentlemen I am much indebted for help and suggestions. The excavations carried out under the auspices of the British Association have been much facilitated by the kind assistance of Mr. Ashman, of Beacon Farm, and Mr. Huntley, of Tadhill Farm, to whom I desire to express my thanks. My thanks are further tendered to the Marquis of Bath and Sir R. Paget, the owners of the land on which the excavations took place, and to their respective agents, Mr. E. C. Treplin and Messrs. Wainwright & Hurd, q2 Vol. 63.] SILURIAN INLIER IN THE EASTERN MENDIPS. 221 the specimen from Beacon Hill described by Dr. Teall ! was probably obtained. Much trap-debris occurs in the northern part of this field. East of the ' Waggon & Horses ' Inn, trap-debris has been found at a number of points, as indicated in the map (fig. 1, p. 220). These indications tend to show that the trap-band here is about 200 yards wide. The westernmost point at which trap is now seen definitely in situ is at a clump of trees about 150 yards west of Sunnyhill Quarry, but the exposure is poor. Sunnyhill Quarry, so interesting from its fine section of tuffs, is principally opened in fresh andesite, which closely resembles that of Moon's Hill as well in its tex- ture and composition as in its generally shattered and slickensided character. Flow-structure is sometimes clearly seen. At one spot the lower part of the trap has caught up and enclosed a mass of red shaly material. The cutting-back of the northern side of the approach to the quarry has exposed a mass of tuff and shaly material about 25 feet thick, underlain by some 25 feet of trap. This is described on p. 223. The Moon's-Hill mass. — A short distance north-east of Sunnyhill Quarry is the big quarry of Moon's Hill, where stone, which is much used locally for road-metal, has been quarried for many years. Moon's-Hill Quarry — by far the largest in the igneous series of the district — is opened in a singularly-uniform mass of compact andesite, dark purple or sometimes dark green in colour, with prominent dark-green augites. It is never markedly amygdal- oidal, and is much shattered and faulted, showing in places strings and patches -of epidote. In the smaller and more northern quarry, and in the little excavation between the two quarries, the rock is more weathered than in the main quarry, but the same general rock-type occurs throughout. It is very difficult to obtain any clear idea, either as to the thickness of the Moon's-Hill trap, or as to its dip. The most prominent divisional planes traversing it dip in a south-south-westerly direction at an angle of about 40°, which would give a strike nearly at right angles to the igneous band as a whole. Mr. Dixon, however, detected a second series of divisional planes, dipping north-north-westward at a very high angle, and thus giving a strike coinciding with that of the igneous series as a whole, and with that of the lines of flow -structure which are some- times visible on the weathered surface. If these divisional planes really indicate the dip and strike of the trap, and if the high dip is maintained and there is no repetition by faulting, the thickness of the trap must be at least 900 feet. It is not, in any case, probable that the trap is less than 400 feet thick at Moon's Hill. Fragments of trap were obtained along the hedge-bank to the south-east of Moon's-Hill Quarry ; but from this point until Tadhill Farm 2 is approached (a distance of about half a mile) no clear 1 ' Summary of Progress of the Geological Survey for 1898' (1899) p. 111. 2 In the 6-inch Ordnance-map two Tadhill Farms are shown — one south of the Frome Road and west of Tadhill House, the other north of the Frome Road and east of Tadhill House. When ' Tadhill Farm ' is referred to in the present paper the former of these is meant. 222 PEOF. S. H. EEYNOLDS ON A SILT7RIAN [May I907, evidence of the presence of trap has been found, and it appears that the band is interrupted, as indicated in the Geological-Survey map. The Downhead and Tadhill mass.— Eastward of this interruption, the westernmost spot where trap occurs is at the corner of a field 300 yards south-west of Tadhill Farm, where its presence was proved by trenching. Unmistakable evidence of the occurrence of the trap is afforded by abundant debris along the hedge-banks in the fields to the south-east of Tadhill Farm ; and at one spot it is found in situ. A little farther east is a considerable exposure in a field, and from this point onwards abundant debris was found as far as the large new quarry at Downhead, where the trap is finely exposed and of the same general type as at Moon's Hill and Sunnyhill. Trap-fragments may be found along the hedge-banks almost everywhere in the area between Tadhill House, Luxton's Lane, and Downhead Quarry. Trap is further exposed in Luxton's Lane, north-west of Manor Farm ; and fragments were found in a field to the east of the lane. (2) The normal Tuffs and the associated Fossiliferous Rocks. Though tuff-debris has been met with at several points (indicated in the map, fig. 1, p. 220) in the western part of the area west- south-west of the ' Waggon & Horses ' Inn, the material may have been derived from the matrix of the coarse ashy conglomerate. Tuff-debris was also noted at a little pond in a field west of Long- Cross Bottom. It is not, however, until Sunnyhill Quarry (Stoke Lane) is reached, that the tuff is seen in situ ; here is exposed the finest and most interesting section in the whole area : the following beds are seen (fig. 3, p. 225) : — Thickness in feet. 8. Andesite to top of section. 7. Rather coarse tuff and shaly material about 25 6. Andesite about 25 5. Tuff, mainly rather coarse 16| 4. Very fine red ash and ashy clay with many small lapilli, ) o passing down into a slightly-coarser red ash J 3. Thickly-bedded, and in the main rather coarse tuff, dark j no when fresh, but weathering pale f 2. Very fine red ash , 3 1. Much weathered, rather fine tuff, mainly soft and yellow, 1 ^ but with harder bands containing Silurian fossils } Total thickness of ashy series seen 160^ The dip of this series is 40 to 45 degrees IN". 20° W., so as to give an east-north-easterly strike, which agrees in the main with that of the igneous series as a whole,and is not very far removed from the strike of the chief axis of the Eastern Mendips. Vol. 6$.~\ IXLIER IN THE EASTERN MENDIPS. 223 Further detail with regard to the tuff in the foregoing section. 7. This mass of tuff and shaly material was exposed during the latter part of 1906 by cutting back the northern side of the approach to the quarry. The top of the series appears to be regularly overlain by the trap, and to dip at 45° to 50° north- north-westward : that is, its dip is similar in amount and direc- tion to those of the tuffs below the whole trap-series. The mass is, however, much crushed and disturbed, and the nature of its junction with the underlying trap (Band 6) could not be ascertained. Although probably interbedded, it is possible that it may be caught up by the trap or faulted in. Very little sign of it could be found in the south side of the quarry, though only some 20 yards distant. 5. Band 5 is of the same general type as Band 3, but is not so well exposed. 4. This is a very variable band, and includes the following rock- types :— (a) Fine, compact, red ashy clay showing no ashy material in a hand- specimen, although with the aid of the microscope the presence of such material can be detected. (b) Soft friable clay and very fine red or purple ash, with ashy particles (of an average length of 1 millimetre) very thickly and evenly distributed. (c) Compact, red ashy clay, with larger lapilli reaching to a length of a centimetre or rather more, and showing a tendency to be arranged in layers. 3. It would be difficult to find a more obvious example of a tuff than this rock, which consists of angular fragments of trap ranging in length from about three-quarters of an inch downward to a size such as to render them indistinguishable in a hand-specimen. 2. This band, which is very poorly exposed, is of the same character as Band 4. 1. The hard bands in this tuff, which is always rather fine-grained, tend to weather yellow or green — not white or various shades of red and brown, as is the case with the other bands. Fossils occur chiefly in the upper part, and in the finer layers. The following fossils obtained from this band have been determined by Mr. F. 11. Cowper Eeed 1 : — Lindstroemia cf. rvgom, Phiii. Strophomena arenacea (?) Salt. Lindstroemia cf. mbduplicata, M'Coy. I Pentamerm (?) rotundus (?) Sow. Orthis (Dalmanella) cleganlula, ; Lingtda cf. Symondsi, Salt. Dalm. (very common). Ovtlionota (I). BJiynchonella Bavidsoni, M'Coy (very Ctenodonta or Lyrodesma sp. common). Pterincea sp. Meristina tumida (?) Dalm. Horioatoma globosum (?) Sow. 1 I wish to express my most sincere thanks to Mr. Cowper Reed, for his kindness in determining my fossils. This is only one of many occasions on which I have been indebted to him. T3 as 8JL ■s Ss t3 o a ° « CO "3 'I ■43 £ ^ § on _o a a> II II II II .9 £ §1 '■a „ 3 S ■53 ►•a Phts 3 1? S s s o .'S r-H