THE QUARTERLY JOURNAL

OF THE GEOLOGICAL SOCIETY OF LONDON

Quod si cui mortalium cordi et curm sit, non tantum inventis h~erere, atque iis uti, sed ad uheriora penetrare ; atque non disputando adversarium, sed opere naturam vincere : denique non belle et probabiliter opinari, sed certo et ostensive scire; tales, tanquam veri scientiarum filii, nobis (si videbitur) se adjungant.--Novum Organum, Prtfatio.

VOLUME LXXXIX

FOR I933

LONDON : LIONGMANS , GREEN & CO: LTD. PARIS : CHARLES KLINCKSIECK~ I I RUE DE LILLE. SOLD ALSO AT THE APARTMENTS OF THE SOCIETY~ BURLINGTON HOUSE~ W.I. I933 GEOLOGICAL SOCIETY OF LONDON LIST OF THE OFFICERS AND COUNCIL

Elected February 17th, 1933

PRgSIDIL~T Sir Thomas Hem'y Holland, K.C.S.I.K.C.I.E.D.Sc. LL.D.F.R.S. VICE-PRESI DENTS l~'of. Edmund Johnston Garwood, M.A. i Walter Campbell Smith, M.C.T.D.M.A. Se.D.F.R.S. I Prof. William Whitehead Watts, LL.D. John Frederick Norman Green, B.A. Sc.D.M.Se. F.R.S.

S ECRETARI ES Prof. William Thomas Gordon, M.A. [ Prof. Percy George Hamnall Boswell, D.Sc. F.R.S.E. I O.B.E.D.Se. F.R.S.

FOREIOH SECRK~ARY Sir Arthur Smith Woodward, LL.D.F.R.S. F,L.S.

TREASURER Frederick Noel Ashcroft, M.A.F.C.S.

COT.TNCW. Frederick Noel Ashcroft, M.A.F.C.S. Prof. William Bmmard Robinson King, Prof. Percy George Hamnall Boswell, O.B.E.M.A. O.B.E.D.Sc. F.R.S. Emil Montag, M.Sc. Prof. William S. Boulton, D.Sc. A.R.C.S. Prof. William John Pugh, O.B.E.B.A. Oliver Meredith Boone Bulman, Ph.D. D.Sc. A.R.C.S.D.I.C. Joha Brooke Serivenor, I.S.0. M.A. Prof. Edmund Johnston Garavood, M.A. Bernard Smith, M.A. Sc.D. Sc.D.F.R.S. Walter Campbell Smith, M.C.T.D.M.A. Prof. William Thomas Gordon, M.A. Leonard Frank Spath, D.Se. D.Sc. F.I~S.E. Herbert HenryThomas, M.A. Se. D. F.R.S. John Frederick Norman Green, B.A. Prof. William Whitehead Watts, LL.D. Prof. Herbert Leader Hawkins, D.Sc. Sc.D.M.Se. F.R.S. Charles William Hobley, C.M.G. Talbot Haes Whitehead, M.Se. A.R.C.S. Sir Thomas Henry Holland, K.C.S.I. Lieut.-Col. Sir Arnold Talbot Wilson, K.C.I.E.D.Sc. LL.D.F.R.S. K.C.I.E.C.S.I.C.M.G.D.S.O.M.P. Prof. Owen Thomas Jones, M.A.D.Se. Sir Arthur Smith Woodward, LL.D. F.R.S. F.R.S.F.L.S.

ASSISTANT SECRETARY AND EDITOR Arthur Greig LIBRARIAN Norman Ernest Pettitt, B.Sc. CLERK LIBRARY ASSISTANT Miss M. S. Coke blisa E. D. Eastwood

Publication Committee Sir Thomas Henry Holland, Pres/deat Prof. W. T. Gordon Prof. P. G. H. Boswell ~ Secretaries Mr. F. N. Asheroft, Treasurer Prof. W. S. Boulton Dr. L. F. Spath Prof. W. J. Pugh Prof. W. W. Watts Dr. Bernard Smith Sir Arnold Wilson Mr. W. Campbell Smith Sir Arthur Smith Woodward TABLE OF CONTENTS PAGE flTJTJTSOI~, ARCHIBALD. The Dalradian Succession in Islay and Jura (Plates XIII & XIV) . 125 fi~NISS, LESLIE GEORGE. The Upper Devonian Rocks of the Chudleigh Area, South Devon (Plate XLI) . 431 BOULTON, WrrJT.TAH S. The Rocks between the Car- boniferous and Trias in the Birmingham District (Plates V & VI) . 53 BULMAN, OLIVER MEREDITH BOONE. See DOUGLAS, JAMES ARCHIBALD. DAVIES, KENNETH ARTHUR. The Geology of the Country between Abergwesyn (Breconshire) and Pumpsaint (Carmarthenshire) (Plates XVII &

XVlII) . 172 & Jon-N ISAAC PLATT. The Conglomerates and Grits of the Bala and Valentian Rocks of the District between Rhayader (Radnorshire) and Llansawel (Carmarthenshire) (Plate XIX) 202 DOUGLAS, JAMES _kRCHIBALD. The Geology of the Marcapata Valley in Eastern Peru; with an appen- dix on the Graptolites by OLrWR MEREDITH BOONE BCLMAN (Plates XXVII-XXXIII) . 308 GEORGE, THOMAS NEVILLE. The Carboniferous Lime- stone Series in the West of the Vale of Glamorgan (Plates XX & XXI) . 221 HAWKES, LEONARD & HILDA KATHLEEN. The Sand- fell Laccolith and 'Dome of Elevation' (Plates XXXV-XXXIX) . 379 INGHAM, ~RANK TINLEY. See WITJJ~OURN, ERIC STEWART. JO~ES, BRYNMOR. The Geology of the Fairbourne- Llwyngwril District, Merioneth (Plates XV & XVI) 145 LO~GSTAFF, JA~E. A Revision of the British Carboni- ferous Members of the Family Loxonematid~e, with descriptions of New Forms (Plates VII-XII) 87 MOURANT, ARTHUR ERNEST. The Geology of Eastern Jersey (Plates XXII-XXVIB) . . . 273 iv TABLE OF CONTENTS PAGE PLATT, JOHN ISAAC. See DAVIES, KENNETH ARTHUR. PULLEY, WmT,TAg. The Iron-0re Oolites and Piso- lites of North Wales (Plate XL) . 401 S--ASD, S. JinxES. The Lavas of Mauritius . 1 SMITH, STArtLEr. On the Occurrence of Tremadoc Shales in the Tortworth Inlier (Gloucestershire), with Notes on the Fossils by Cyam J~s STUBBLEFIELD (Plate XXXIV). 357 STUBBLEFIELD, CYRIL JA~r~s. See SMITH, STANLEY. WELCH, FRANCIS BRIA~ AWBURN. The Geological Structure of the Eastern Mendips (Plates I-IV) 14 WILLBOURN, ERIC STEWART, • FRANK TINLEY INO~AM. The Geology of the Seheelite Mine, Kramat Pulai Tin Limited, Kinta, Federated Malay States (Plates XLII-XLVIII) . 449 WXLSON, VERNON. The Corallian Rocks of the Howard- ian Hills (Yorkshire) (Plates XLIX & L) 480 PROCEEDINGS PAGE Proceedings of the Meetings . i, cv Annual Report of the Council xiii List of Donors to the Library xxi List of Officers and Council . xxx List of Foreign Members xxxi List of Foreign Correspondents xxxii Lists of Wollaston Medallists and recipients of Wol- laston Fund . . xxxiii Lists of Murchison Medallists and recipients of Mur- chison Fund . - xxxiv List of Lyell Medallists and recipients of Lyell Fund xxxv, xxxvi List of Bigsby Medallists xxxvi Applications of the Prestwich Bequest and the Barlow- . .. Jameson Fund . xxxwl Awards of the Daniel-Pidgeon Fund xxxviii List of recipients of grants from the J. B. Tyrrell Fund . xxxix Estimates for 1933 xl Accounts for 1932 xlii Awards of the Medals and Proceeds of the Funds liv Anniversary Address of the President (The Geo- logical Age of the Glacial Horizon at the Base of the Gondwana System) . lxiv Obituary Notices of Fellows, Foreign Members, and Foreign Correspondents deceased . . lxxxvii

DEWEY, H., & others. The Falling Water-Level in the Chalk under London . cxvi Jo~r~.s, O. T., & others. The Development of Frac- tures in the Earth's Crust . vi LONGF1-ELD, T. E., & others. The Subsidence of London . cv LEAEv.Y, L. S. B. Fossiliferous Deposits in the Homa-Kendu Area, Kenya Colony . cxii l~wsoN, Sir DOUGLAS. The Geology and Glaciation of some Islands of the Southern Ocean and the newly-discovered Antarctic Mainland . cxiii DATES OF ISSUE OF VOLUME LXXXIX Part 1 : pages 1-86, plates I-VI February 28th, 1933. Part 2 : pages 87-201, i-lxxxvi, plates VII-XVIII . May 25th, 1933. Part 3" pages 202-356, lxxxvii- cxxiii, plates XIX- XXXIII August 25th, 1933. Part 4 pages 357-526, plates XXXIV-L, title-page and index . November 28th, 1933. LIST OF THE FOSSILS FIGURED AND DESCRIBED IN THIS VOLUME

SPECIES AGE I LOCAIATY PLATE [ PAGE

GRAPTOLITOIDEA Amplexocraptus perexcat~gtt~ Llanvirnian Quitari (Peru) XXXIII, 9a, b 352 (Lapworth) var. Cryptograptu~ schdferi (Lap. do. do. XXXIII, 8a~-c 352 worth) var. latus nov. DiceUograptus sp. do. do. XXXIII, 3a, b 350 I)id~ptus dimacograp. do. do. XXXIII, 5 349 toides Holm MS.

aft. euodus Lapworth do. do. XXXIII, 6a-c 350 " -. murchisoni (Beck) var. do. do. XXXIII, 4 349 9eminu~ (~isinger) stabil~ ~,lles & Wood do. do. XXXIII, 2 349 ~sp. do. do. XXXIII, 1 349 Glyptograptu.~ dentatas (Bron- do. do. XXXIII, 7a4 351 gniart) rout. BRACHIOPODA. Zeptobolus ins/gn/s Hall rout. Lower Ordo- ] Yuscamayo R. XXVYII, 8a, b 342 /atu8 Ruedemann vician I (Peru) IAngulella spp. Breadstone I Bmadst~ne (Glos.) XXXIV, 5 365 Shales Orthis sp. IAanviruian Yanahurco R. (Peru) XXT'III, 9 343 LAMELLIBRA/%'CHIA C~bicula sp. I X.XVIII, I 336 1Cretace~ (Pem)TertiaryRedBeds 1 Huayllumbe

Cyrena sp. do. do. XXVIII, 2 336 GASTRI ,PODA Anoptychia $ impendens (Mc- Carbonlfer- Chicken Hill (Lime- IX, 5 107 Coy) ous rick) Bellerophon spp. Breadstone Breadstone ((}los.) XXXIV, 6 365 Shales Eoptychia caledonien~is sp. nov. Carbonifer- Rcecobie (Fife) X, 4-6 114 ous #u/cata de Koninck do. BaUadoole X, 1-3 113 (I.o.M an) tenuistriata (l'ortlock) do. Aghalmrcher IX, 1 115 (Tyrone) ventricosa sp. nov. do. Narrowdale (Staffs.) X, 7, 8 114 Hemizyga dathratula (Young & do. Various Scottish XI, 1-4 106 Armstrong) Katosira ~nithiana sp. nov. do. Dykes (Kilburnie) XI, 6-8 105 ~nightia irregularij sp. nov. do. Dykes (Kilburuie) & XII, 4--6 119 Law (Dairy) Melania ~p. Cretaceous- Huayllumbe (Peru) XXVIII, 7 335 Tertiary Red Beds M icroptych i~ co~tricta (Martin) Carbonifer- Tideswell (I)erbysh.) X, 9-11 109 ous & Axton (Flint) jacksont sp. nov. do. Castleton (I)erbysh.) IX, 8, & X, 12 111 & Narrowdale Pit (rrarUngton) pygrnvea sp. nov. do. Law (Dalry) & XII, 1-3a 111 Dykes (Kilburnie) subconstricta (de Koninck) do. Balladoole (I.o.Man) IX, 6, 7 II0 & Settle wrighti Longstaff do. Little Island (Cork) 109 Platyconcha dunlopiana sp. nov. do. Craigenglen (Camp- XI, 12-15 116 sie) hindi nom. nov. do. Nettlebank (Staffs.) XI, 5 118 tenuilineata sp. nov. do. Robroyston (Glas- XI, 9-11 117 gow) & BarmuUock .,~ VIII FOSSILS FIGURED AND DESCRIBED

SPEC~ I AGE [ LOCALrrY I PLATR IPAGE

GASTROP0 D A~Continued Pleurocera sp. Cretaceous- Huayllumbe (Peru) X X'VIII, 3-6, 335 Tertiary text-fig. 4 Red Beds gygopleura benniana sp. nov. Carbonifer- Law (Dalry) VIII, 9-19 102 ous brev/s (McCoy) do. Toberory, Tulsh IX, 9 98 (Ireland)

- -- ~ var. tz~ss/costata ~. do. Settle IX, I0 99 - -- p~ma McCoy do. Lachagh, Drumquin VIII, 16 97 (Tyrone) -~ reden~ rp. nov. do. Penchford Bum, VIII, 8 104 Redewater (Northumb.) -- robroystonen~iarp. nov. do. Robroyston (Gls~ i VIII, 1, 2, 5 100 gow) -~ ~ vat. tenuicostata nov. do. do. & Penbreck VIII, 3, & XI~, 102 (MuirkiA) 8, e ~ vat. y,n,,~Zia,a nor. do. Robroyston (Glas- VIII, 6, 7 I01 gow) r~ ~p. nor. do. Roscobie (Fife) & VIII, 13-15, & 09 Law (Dab-y) XII, 7 - rug/fera (Phillips) do. Various VII, 1-4, 13, 14 02 ~ vat. minima (Sower- do. Coalbrookdale & VII, 12, 15, 16 03 by) Law (Da~-y) ~ vat. cylindracea nor. do. Law (DaVy) & VII, I0, 11, 17 04 Dykes (KilbumJe) ~ . var. rub~planata nor. do. Roscobie (Fife) WIT, 6, 7. 04 ~ ~ vat. tenuinodosa Twr. do. Ardross (~fe) VII, 8 05 --~ ~ vat. rowland~ nor. do. Glenwhapple Burn VII, 5, 9 05 CLennoxtown) & A_~dross (Fife) #m/afo/dea (Phillips) do. Bolland & Longnor IX, 11-13 do. Longnor IX, 14 nor~ ~/~u~sa (Phillips) do. Kildare & Bolland VIII, 17, & IX, 2, 3 CEPWA TL)PODA Engonocer~ ,p. ] Lower2vician Ordo- Yuscamayo(Peru)Yanahurc~ R. & ] X-XIX, 1, J342 CRUSTACEA 8e~tade/2a ]m:l-~m~n~ ~p. nor. I Breadstoneshales I "Breadstone (Glos.) I text-fig. 2 371

TRILOBITA *XYTV, 7, 8 366 Agnostu~ ca/t~ Lake 1 Breadst~Shales Breadst~ e (Gl~ Jgdldla depream (Salter) do. do. YYYI~, 1, 9-11 366 Homotelu~ zp. Ll~nvirnian Yanshurco R. X~?III, 11-14 344

~V/obe/~a [N/obe] t~nfmyi vax. Breadstone (GIos.) X ){X'I-V, 2-4 368 mit/d nov. Shales Tr/arthru.~ ap. Llanvirnian Yuscamayo R. Y~.IX, 3-6 345 (Peru) Tr/nudeu4 ~p. do. "Ya.n~.rco R. ~ X'I'~, 8 346 (Peru) LIST OF THE PLATES IN THIS VOLUME _~aein#page PLATE I. Thrust-plane in Quarry No. 3, western bank, Vallis Vale (Somerset) . 50 ,, II. Nunney quarry (Somerset), showing 'pivot thrust- fault' 50 ,, III. Geological map of the eastern Mendips . 50 ,, IV. Geological sections through the eastern Mendips 50 ,, V. Contour map of the base of the Trias in the Birming- ham area . 82 ,, VI. Barr Beacon Beds exposed in sandpit near Barr Beacon (Staffs.) . 82 ,, VII. Zygopleura rugifera and varieties . 122 ,, VIII. Zygopleura 122 ,, IX. Eoptychia, Zygopleura, Microptychis, and ~Anaptyehia 122 ,, X. Eoptychia and Microptychis 122 ,, XI. Hemizyga, Katosira, and Platyconcha 124 ,, XII. Microptychis, Knightia, Zygopleura 124 ,, XIII. Ripple-marked current-bedding in dolomitie silt- stone, Islay, and graded bedding in the Scarba Conglomeratic Group, Jura 142 ,, XIV. Geological map of Islay and Jura 142 ,, XV. Coast section near Llwyngwril, Merioneth 170 ,, XVI. Geological map of the Fairbourne-Llwyngwril dis- trict, Merioneth . 170 ,, XVII. Map illustrating the geology of the country be- tween Abergwesyn (Brecon) and Pumpsaint (Car- marthen) . 200 ,, XVIII. Views from near Ystradffin (Carmarthen) . 200 ,, XIX. Map illustrating the disposition of arenaceous material in the country between Elan Valley (Rhayader) and Pumpsaint 218 ,, XX. Geological map of the west of the Vale of Glamorgan 270 ,, XXI. The north-western flanks of Ogmore Down, the core of the Candleston anticline, and Porthcawl Flats and Newton Down 270 ,, XXII. Jersey rhyolites 304 ,, XXIII. Les Rouaux, Jersey, and flow-banded, non- porphyritic rhyolite . 304 ,, XXIV. Flow structure in porphyritic andesite, Jersey . 304 ,, XXV. Blocks of andesite arrested in process of being broken up and engulfed in granite 304 LIST OF THE PLATES IN THIS VOLUME Fac/n~y page PLATE XXVIA & B. Geological map of, and sections across, eastern Jersey . 304 ,, XXVII. Igneous and metamorphic rocks from the Mar- capata Valley, Peru . 354 PLATES XXVIII & XXIX. Fossils from Peru 354 PLATE XXX. The Pass of Chimboya 354 ,, XXXI. The Marcapata Valley, Peru . 354 ,, XXXII. Gorge on the Huayllumbe River, Peru . 354 ,, XXXIII. Llanvirnian graptolites from Peru 354 ,, XXXIV. Fossils from the Breadstone Shales of the Tort- worth inlier 376 PLATES XXXV-XXXVIII. Photographic views of Sandfell, Ice- land . 398 I~_~TE XXXIX. Map of the Sand/ell laceolith, Iceland . 398 ,, XL. Textures and minerals in the iron-ore oolites of North Wales 426 ,, XLI. Upper Frasnian goniatites from Lower Dunscombe, Devon 446 PLATES XLII-XLVII. Views of the Kramat Pulai Scheelite Mine, Kinta, and of the ore occurrences in the mine 478 PLATE XLVIII. Geological map of the Scheelite Mine and Mine 7A, Kraznat Pulai, Kinta 478 ,, XLIX. ' Urchin Dirt Beds ' facies, Braygate Road quarry, near Swinton Grange, and Coral Rag above oolitic limestone, railway embankment quarry, between Settrington and North Grimston 506 ,, L. Rhaxella spicules in Lower Calcareous Grit 506