®mntl\ Wlummty ff "targ ; i JOUGHT WITH THE INCOME FROM THE SAGE ENDOWMENT THE GIFT OF FUND ^^^M^^^lv ficnrtj W, Sage 1891 ENGlNlIRING LiBRARY Mi.3.kzf... '¥/.$./£$£... Cornell University Library QE 262.C171W57 1891 The geology of parts of Cambridgeshire <• 3 1924 004 550 525 '/©)// uiiiiu m^. Cornell University Library The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924004550525 MEMOIRS OF THE GEOLOGICAL SURYEY. ENGLAND AND WALES. - THE GEOLOGY OF PAETS OF CAMBRIDGESHIRE and of SUFFOLK (ELY, MILDENHALL, THETFQRD) „ (EXPLANATION OF SHEET 51 N.E. WITH PART OF 51 N.W.) w , BT W. WEITAKER, B.A, F.R.S., F.G.S., Assoc. Inst. C.E. (Editor), H. B. WOODWARD, F.G.S., F. J. BENNETT, F.G.S.* S. B. J. SKERTCHLY, F.G.S.,-and A. J. JUKES-BROWNE, B.A., F.G.S. PUBLISHED BT OKDEB OF THE LOKDS COMMISSIONERS OS HER MAJESTY'S TBEASUKT. LONDON: PRINTED FOE HER MAJESTY'S STATIONERY OFFICE, BY BYRE AND SPOTTISWOODE, v PBIHTEBB 10 THE QUEEN'S MOST EXCELLENT MAJESTY. And to be purchased, either directly or through any Bookseller, from EYRE akd SPOTTISWOODE, East Hakding Steeet, Fleet Stbbet, E.O.; or JOHN MENZIES & 00., 12, HaSovbb Stbbet, Edihbuboh, and 83 and SKVWest JTiLB Steeet, Ulasoow ; or ■,f» HOPQES, , FIGGIS, & Co., 10*, iGBAEioir Street, Vvjuhb. 1891. Price Two Shillings. LIST OF MAPS, SECTIONS, AND OTHER PUBLICATIONS OF THE GEOLOGICAL SURVEY. Tbb Maps are those of the Ordnance Survey, geologically coloured by the Geological Survey of the United Kingdom, unde the Superintendence of Sir Ajkch.Geikib.LL.1J. , F.R.S., Director General. „ ., , . .. ... (Por Maps, Sections, and Jduinoirs illustrating Scotland, Ireland, and the West Indies, and for full particulars of all pnbllM tions, see "Catalogue." Price Is.) ENGLAND* AND WALES.— (Scale one-inch to a mile.) Maps marked * are also published as Drift Maps. Those marked t are published only as Drift Maps. Sheets 3', 5, 6», 7*, 8*, 9, 11 to 22, 25, 26, 30, 31, 83 to 37, 40, 41, 44, 47*, 64*, 65t, 69t,70*, 83', 86*, price 8*. 6d. each. Sheet 4, 5s. Sheets 2*, 10, 23, 24, 27 to 29, 32, 38, 39, 58, 8tt, 85t, 4s. each. I. of Wight (New Series), 6». Sheets divided into quarters ; all at 3s. each quarter-sheet, excepting those in brackets, which are Is. Bd. each. 1*. 42, 43, 45, 46, NW, SW, NE*, SE, 48, NWt,Sff«, NEt, (SE*), I49t), 50t, 51*, 52 to 57, (57 NW), 59 to 63, 66 SWt KBt SE*, 97 NW*, SW. NE\ SE, 98 NW, SW, NE*. SE, 99 (NE*), (SE*), 101 SE, NE*, 102 NE*, 103*, 104', 106 KW, SW, (NE*), SB, 106 NW*. S W, NE* SE* 107 SWt, NE*, SE*, 108 SW*, NE*, SE*, 109 SW, SE*, 110 (NW), (NE'), SE'.SW; HORIZONTAL SECTIONS, VEXTICAI SECTIONS. 1 to 146, England, price 5s. each. i to 78, England, price 3s. 6d. each. COMPLETED COUNTIES OF ENGLAND Am WALES, on a Scale of one-inch to a. Mile. Sheets marked • have Descriptive Memoirs. Sheets or Counties marked t are illustrated by General Memoirs. ANGLESE I t — 77 N, 78. Hor. Sect. 40. BEDFORDSHIRE— 46 NW, NE, SWt, SEt, 52 NW, NE, SW. SE. BERKSHIRE— 7*, 8t, 12*, 13*, 34*, 45 SW*. Hor. Sect. 59, 71, 72, 80. BRECKNOCKSHIRE!-,— 36, 41, 42, 56 NW, SW, 57 NE, SE. Hor. Sect. 4, 5, 6, 11, and Vert. Sect. 4 and 10. BUCKINGHAMSHIRE,-?* 13* 45* NE, SE. 46 NW, SWt, 52 SW. Hor. Sect. 74, 79. CAERMARTHENSHlREt,S7,S8, 40, 41, 42 NW, SW, 56 SW, 67 SW, SE. Hor. Sect. 2-4,7,8 ; and Ver*. Sect. S-6, 18 14 CAERNARVONSHIRE^— 74 NW, 75, 76, 77 N, 78, 79 NW, SW. Hor. Sect. 28, 31, 40. CAMBRIDGESHIRE.t-43 NE, 47*. 51*, 52 SE, 61*. CARIUGANSHIREt,— 40, 11, 56 NW, 67, 58, 59 SE, 60 SW. Hor. Sect. 4, 5, 6. CHESHIRE— 73 NE, NW, 79 NE, SE, 80, 81 NW*, SW, 88 SW. Hor. Sect. 18, 43, 44, 60, 64, 65, 67, 70. CORNWALLt,— 24t, 25t, 26t, 29t, 30t, 31t, 32t, & 33t. DENBlGHt,-73NW,74,75NE,78NE,SG,79NW,SW,SE,8!)SW. Hor. Sect. 31,35, 38, 89, 43, 44; andVert Sect 24 DKRBYSHIREt,-02NE,63NW,71NW,SW,SE,72NE,SE,81,82,88SW,SE. Hor. Sect. 18, 46, 60 61 69 70 -DEVONSHIREt,-20t, 21t, 22t. 23t, 24t, 25t, 26t,& 27t. Hor. Sect. 19. DORSETSHIRE,— 15, 16, 17, 18, 21, 22. Hor. Sect. 19, 20, 21, 22, 56. Vert. Sect. 22, ESSEX— 1*. 2*, 47*, 48. Hor. Sect. 84, 120. FLINTSHIREt — 74 NE, 79. Hor. Sect. 43. 10, 47. to 51. GLAMORGANSHIREt,-20, 36, 37, 41, The MEMOIRS of the GEOLOGICAL SURVEYof GREAT BRITAIN. To? I tu ■ vfi, *}? PE0P - ^iilips (OP N. WALES. By Sib A. C. Ramsat. App., by J. W. Saltek and R. ETHEiuiai 2nd Ed ,, - ( '?i Parts >.«*. LONDON BASIN. Pt.I. Chalk 4 Kocene of S.& W. Tracts. Bv W. WhitimTh h ,vl\. (V ° h UI -o> Memoirs 4c' Guide to the GEOLOGY of LONDON and the NEIGHBOURHOOD. b/wVeta™ ^° fMem ™Uc.) TERTIARY FLUVIO-MARJNE FORMATION of the ISI.E of WIGHT Byl, wA n *™ ^ The ISLE OF WIGHT. By H. W.Bh»iow. New Ed. B^C.EZduC" * ^ MEMOIRS OF THE GEOLOGICAL SUEYEY. ENGLAND AND WALES. THE GEOLOGY OF PARTS OF CAMBRIDGESHIRE and of SUFFOLK (ELY, MILDENHALL, THETFOED) (EXPLANATION OF SHEET 51 N.E. WITH PART OF 51 N.W.) BY W. WHITAKER, B.A., F.R.S., F.G.S, Assoc. Inst. O.E. (Editor), H. B. WOODWARD, F.G.S., F. J. BENNETT, F.G.S., S. B. J. SKERTCHLY, F.G.S., and A. J. JUKES-BROWNE, B.A., F.G.S. PUBLISHED BY ORDER OP THE LORDS COMMISSIONERS OF HER MAJESTY'S TREASURY. LONDON: PRINTED FOR HER MAJESTY'S STATIONERY OFFICE, BY EYRE AND SPOTTISWOODE, FRIHTEBS TO THE QUEEN'S MOST EXCELLENT MAJESTY. And to be purchased, either directly or through any Bookseller, from BYRE and SPOTTISWOODE, East Harding Street, Fleet Street, E.G.; or JOHN MENZIES & CO., 12, Hahovee Street, Edinburgh, and 8S and 90, "West Nile Street, Glasgow ; or HODGES, FIGGIS, & Co., 104, Graeton Street, Dublin. 1891. Price Tivo Shillings. PREFACE. The present Memoir, descriptive of Sheet 51 N.E. and the north-eastern half of Sheet 51 N.W. of the Geo- logical Survey Map, gives an account of the Geology of parts of the counties of Cambridge and Suffolk, embracing the Isle of Ely, the towns of Thetford and Mildenhall, and the large villages of Soham, Fordham, and Isleham, besides the Icklinghams and Lakenheath (so well known in connexion with flint implements), and "Wicken (noted for its phosphates and the Upware ridge). The larger part of the area was surveyed by Mr. Skertchly, and the rest mostly by Mr. Bennett, the other officers having either mapped or revised small parts. The preparation of the Memoir has been entrusted to Mr. "Whitaker. Besides editing it he has also contributed many general and some detailed notes, the chief portion of the well-sections and the supplementary bibliographies. Mr. Jukes-Browne's later work among the Cretaceous rocks has enabled him to contribute most of the account of the Gault and of the Chalk, in which he was aided by Mr. W. Hill, whose kind help the Geological Survey has already had occasion to acknowledge. The present Memoir completes the description of the neighbourhood of Cambridge. Perhaps the most in- teresting geological features in it are the Corallian ridge of Upware, surveyed and described by Mr. "Woodward, and the large boulder of Eoslyn Hole, Ely. The imple- ment-bearing drifts are described in Chapter VII., and the account of the Fenland is chiefly taken from the Survey Memoir on that district. ARCH. GEIKIE, 31st March 1891. Director- General. U 63615. 500.— 6/91. Wt. 5132. a 2 IV The parts by the various authors, named on the title-page, are on the following pages : — W. Whitakee, 1-4, 6, 20-34, 37-39, 43, 45, 47-57, 59-64, 70-78, 80, 81, 87-90, 101 to end. H. B. Woodward, 6-16, 28, 33, 36, 75, 101, 104. F. J. Bennett, 2, 49-55, 59, 60, 62, 70, 71, 73, 75-78, 80, 89, 108, 113-115. S. B. J. Skertchly, 4, 5, 9-11, 16, 21, 22, 26, 28, 29, 33, 36, 37, 45-49, 51-60, 62-72, 74, 77, 79-81, 88-101, 103, 105-107, 111, 113. A. J. Jukes-Browne, 4, 25, 32-44, 72. CONTENTS. Page Preface, by the Director-General - - iii Chap. I. Introduction. Area of the District. Rivers. Geological Formations and their Range. Shape and Character of the Ground 1 Chap. II. Jurassic Beds. Oxford Clay. Corallian Beds (General Remarks. Ampthill Clay. Coral Rag. Fossils of the Coral Rag). Kimeridge Clay (General Remarks. Local Details. Fossils) - - - 6 Chap. III. Cretaceous Beds below the Chalk. Lower Greensand (Main Mass. Outliers. Fossils). Gault - - 20 Chap. IV. Chalk. Lower Chalk (General Description. Cambridge Greensand. Chalk Marl and Totternhoe Stone. Zones of Holaster subglobosus and of Belemnitella plena. Fossils). Middle Chalk (General Description. Melboura Rock and Zone of Rhynchonella Cuvieri), Upper Chalk - - 34 Chap. Y. Glacial Drift. Beds below the Boulder Clay (South of the Lark. Between the Lark and the Little Ouse. North of the Little Ouse) ....... 48 Chap. VI. Glacial Drift. Boulder Clay (General Account. Local Details). Gravel, Sfc. above the Boulder Clay - - 61 Chap. VII. Post Glacial Drift. Cravels of Ancient Rivers. River Drift (Valley of the Kennet. Valley of the Lark. Valley of the Little Ouse. Valley of the Ouse). Flint Implements. Various Beds not shown on the Map - -72 Chap. VIII. Alluvium. The Fens, including the Valleys of the Ouse and of the Cam (The Peat. The Shell-Marl. Sections. Fossils). Tributary Valleys ------ 90 Chap. IX. Economic Geology. Coprolites. Building Materials (Stone. Lime. Bricks, &c). Peat. Underground Water - 103 Appendix I. Notes supplementary to the Memoir on Sheet 51, S.E. 109 Appendix II. "Well-sections. Cambridgeshire. Huntingdonshire. Norfolk. Suffolk 110 Appendix III. Supplementary Bibliographies. Cambridgeshire. Suffolk ... - - 120 Index 124 U 63615. VI ILLUSTRATIONS. Page Fig. 1. — Section north of Upware. (H. Keeping.) > - - 23 „ 2.— The Upware Section. (W. Keeping.) - - 27 ,, 3. — Section in a Pit south of Barton Mill. (F. J. Benneti.) - 49 ,, 4. — Section in a Pic south of Tuddenham. (S. B. J. Skertchly.) 49 ,, 5. — Part of the Section at Culford Brickyard. (S. B. J. Skertchly.) - - - - - - 51 ., 6. — Section in a Pit near Livermere Heath Farm, north of Ampton. (S. B. J. Skertchly.) - - - - 52 ,, 7. — Section at Elvedon Gap Brickyard. (S. B. J. Skeetchly.) 54 „ 8. — Section at Mildenhall Brickyard. (S. B. J. Skeetchly.) - 56 ,, 9. — General Section ab Warren Hill, east of Mildenhall. (S. B. J. Skeetchly.) - - - - - - 56 ,, 10. — General Section along the Boad from Thetford Bail way Station to the Waterworks. (S. B. J. Skertchly.) - 58 ,, 11. — Section in a Pit south of Thetford Waterworks. (F. J. Bennett.) - - - - - - - 59 ,, 12— SectioninaPitamileN.N.E.ofThetford. (W. Whitaker.) 60 „ 13— Plan of Eoslyn Hole, Ely. (S. B. J. Skertchly.) - - 65 ., 14— The Great Erratic, Eoslyn Hole, Ely. (S. B. J. Skertchly.) 67 „ 15.— The Chalk Boulder at Eoslyn Hole, Ely. (S. B. J. Skertchly.) - - . . . - 69 „ 16 — Section of Part of the Cutting on the Newmarket and Ely Bailway between Landwade and Snailwell. (W. Whitaker.) - - - - - . - 73 .,17. — Chalk-surface at Lakenheath. (S. B. J. Skertchly.) - 74 ,, 18. — Section at the Beeches Pit, between Icklingham and West Stow. (S. B. J. Skertchly.) - - - - 79 ,, 19. — Flint Implement, from Eamparc Hill, Icklingham. (Dr. Evans.) . - - . - 82 ,,20. — Flint Implement, from Icklingham. (Dr. Evans.) - . 82 ,. 21— Warren Lodge. Bedbill, Thetford. „ 22— ,. 23— „ 24— „ 25— „ 26— „ 27.— Marshall's Yew, Wood Fen. (S. B. J. Skertchly.) „ 28.— Yew growing upon Oak, Wood Fen. (S. B. J. Skertchly.) „ 29. — Fir clasping Oak, Wood Fen, near the old Blue Boar (S B. J. Skertchly.) - 1 „ 30.— Fir astride Fir, Wood Fen. (S. B. J. Skertchly.) - „ 31.— Section in a Pit at St. Edmund's Hill, eastward of Burv (J. H. Blake.) - ■ . . . y [ 83 84 84 85 86 87 94 96 109 THE GEOLOGY OF PARTS OF CAMBRIDGESHIRE AND OF SUFFOLK. CHAPTER I. INTRODUCTION. Area of the District. The area to be described consists of about 205 square miles, in Sheet 51, N.E., with about 90 in 51, N.W., or nearly 300 in all, the southern and the western parts of the latter map having already been described in a previous Memoir,* as also have the Fen beds in both maps ;t but in the latter case some parts will be here repeated, so as to make this Memoir more perfect for the tract described. With the exception of some three square miles in the north- eastern corner, including most of the town of Thetford, which is in Norfolk, the greater part of our district is in Suffolk, with the sole town of Mildenhall ; but, on the west, it is in Cam- bridgeshire, with the city of Ely. Besides the places mentioned there are, however, many large villages. The district is purely agricultural, the pits for chalk, clay, gravel, &c, and the getting of peat in parts of the Fens, being the only signs of mineral industry, now that the coprolite- diggings have died out. * The Geology of the Neighbourhood of Cambridge. By W. H. Pbhning and A. J. Jukes-Bkowne. 1881. t The Geology of the Fenland. By S. B. J. Siertchly. 1877. U 63615. A 2 RIVERS AND GEOLOGICAL FORMATIONS. ElVERS. The whole of the district is in the drainage-system of the Ouse, which river forms our boundary along its course from west of Haddenham eastward to Stretham, where it turns N.N.E. and flows hy Ely into the Great Fen. At the village of Thetford (not the town of the same name), south of Ely, the tributary Cam joins the main river, from the south. The brook from Exning (on the south), which enters the district south of Landwade, runs at first northward, but soon turns westward into Burwell Fen, the drainage of which reaches the Cam at Upware. The stream with which we have most to do is the Lark, which, entering the district on the S.E. at Fornham St. Martin, flows in a general west-north-westerly course past Mildenhall, and joins the Ouse three miles N.E. of Ely, at the very margin of Sheet 51, N.W., after a course of 28 miles. On its left, or southern, side the Lark, receives the following tributaries : — (1.) Opposite Icklingham a stream from the south. (2.), Just east of Little Barton the short brook that rises in the chalk-tract at Herrings well. (3.) Between Isleham and Wor- lington the Kennett, which enters the district at Kentford and flows thence W.N.W. (4.) The brook that rises at Newmarket, just beyond our district, flows northward into Isleham Fen, through which 'it seems to reach the Lark. On its right, or northern, side the Lark receives but one tributary, the westerly-flowing brook from Livermere, just beyond our eastern boundary, which itself receives a little tributary from Wordwell, close by the junction with the Lark. The Little Ouse runs through the north-eastern corner of the district, from Barnham St. Gregory to below Thetford. The brook that rises south of Eriswell flows in a north-north-westerly direction into this river. W. W. The chalk-streams fluctuate very much in volume, and some- times are quite dry in parts, their usual sources being, as a rule, high up in the Chalk. The Lark was at one time navigable as far up as Bury, being canalized thus far ; but the locks were not kept up, and so fell into decay ; the stream, too, in many places became choked with weeds, and barges came up no higher than Mildenhall at the time of our survey. The canal, however, is now being revived so that the navigation will again be extended upward. F. J. B. Geological Formations and their Range. The district contains a somewhat varied set of formations the eastern and larger part consisting of Cretaceous beds whilst the western part consists chiefly of Jurassic, there being a slight GEOLOGICAL FORMATIONS. general dip in a south-easterly direction. The divisions that have been recognised are as in the following table : — Eeoent Post Glacial Drift Glacial Drift Cretaceous - Jurassic Alluvial beds {|S Eiver Drift - { Loam Shell-marl. and Alluvium. Chalk - Gravel and Sand. Gravel of Old Rivers. "Gravel. Boulder Clay. Loam. Gravel and Sand. _ Boulder Clay (local). Upper Chalk. Middle Chalk. - <( Lower Chalk, including the Chalk Marl. Gault. Lower Greensand. Kimeridge Clay. Corallian Beds. In the western part of Sheet 51, NVW. (not included here), Oxford Clay occurs. • Corallian Beds have been mapped only in the Upware peninsula, where they are represented by the Coral Rag and the Coralline Oolite (as defined by Blake and Hudleston). They probably have but a very small range underground. The Kimeridge Clay is seen only in the islands in the Fen, including the large mass on which Ely stands. It probably ranges underground eastward for some way, perhaps to beyond our district. The Lower Greensand is seen in outliers or in small isolated patches, on the west, being hidden, for most of its course, under the Fens. It probably extends some way underground to the east ; but it is by no means certain to occur right through the district. The Gault also is mostly hidden in like manner, being seen only in the Soham peninsula, except for insignificant outliers. From what we know of this formation elsewhere we may safely calculate on its persistence underground, far beyond our present bounds, to the eastern coast on the one hand and to the southern outcrop of Kent and Surrey on the other. The Chalk excels all our other divisions, both in thickness and in the area taken up, being either at the surface, or next underlying the Drift, over the greater part of our district, and ranging thence northward to the sea, and in other directions (except westward and north-westward) underneath the various divisions of the Drift, of the Crag, and of the older Tertiary beds. The various divisions of the Drift are scattered irregularly over all the above formations, those of later age following the courses A 2 GEOLOGICAL FORMATIONS. of the valleys, whilst the others occur both over the higher ground and descending into valleys. , The Alluvial beds form flat marshes along the streams, which run westward to the broad flat tract of the Fens. Shape and Character of the Ground. Our district may be said to consist of two plains. The lower one, that of the Fens, consisting chiefly of peat, and but little above the level of the sea, remarkably even, and continuous, that is to say not being cut through, but bounded only by the various masses of higher land that rise from out of it. The higher plain on the other hand, which is formed almost wholly of the Cretaceous beds and their cappings of Drift, rises slightly eastward, where the highest ground is found (though this pro- bably nowhere reaches to 200 feet above the sea-level), and is not continuous, but cut through by the many valleys, and, on the west, by the Fen itself. The higher plain is of much older date, has been formed by erosion, and has then been largely destroyed by eroding forces, the rivers having cut for themselves wide valleys through it ; the lower plain is geologically quite modern, having been formed in the latest geologic period, by deposit, a deposit which is still going on, at its seaward end, The Wash. Owing to the cappings of Drift, as well as to the amount of sand that seems to have been blown over the Chalk, the usual features of a chalk- tract are almost absent. We have no sharp escarpment, no deep valleys, and the flood of sand hag given rise, in places, to barren heath-land, almost alike over the Boulder Clay (where that, too, is covered by the sand) and the Chalk. Over such tracts, as in the north-eastern part of the district, the only profitable crops seem to be rabbits, and sometimes firs and larch, of which large plantations have been made. That part is indeed little else than a gigantic rabbit-warren, the skins of the animals being valuable for the manufacture of felt, &c. Winged game also abounds. With regard to the absence of a marked escarpment of the Chalk Mr. Skertchlt remarks that " it is clear that such a feature once existed, but has succumbed to subaerial denudation during and since the Glacial Epoch." Mr. Jukes-Browne sug- gests that the dying out of the Chalk Rock (see p. 43) may have much to do with the absence of a well-marked rido-e. There is, however, a fine escarpment for long distances, in more southern chalk-tracts, where Chalk Rock has not been found. Speaking of the north-eastern corner of the district, with the bordering tract to the north (in Sheet 65), Mk. Skertchly says (in a note of about 1872) : " From Thetford to the Fens so barren is the land that one is often reminded of the deserts of Africa rather than of English scenery. Hardly a drop of surface-water SHAPE OF GROUND. 5 is to be found, and for miles there is neither ditch, pond, nor spring. Little cultivation is possible ; but the loose sandy soil is occasionally tilled, the rental averaging about three shillings an acre. Rye is the dominant cereal, and fifty years ago was still the staple bread-stuff of the poor. Barley of good quality is grown in places, and lupins have been extensively grown of late years, for sheep-feeding. An attempt has been recently made to introduce comfrey, but this plant has hardly had a fair trial. Potatoes of good quality, and very free from disease, are grown on the poorest sands, but the crops are not heavj\ Buckwheat seems to thrive." CHAPTER II. JURASSIC BEDS. Mr. H. B. Woodward, who mapped the Corallian Beds of Upwareand made some addition to the Kimeridge Clay south of the Ouse, and who has heen engaged for some years in the examination of the Jurassic formations of the South of England has written the following description of the beds from the Oxford Clay to the Kimeridge Clay, to p. 16, some notes by Mr. Skertchly being included. Oxford Clat. This formation consists of greenish-grey and bluish-grey clay, with septaria, selenite, and occasional layers of sandy lime- stone. GryphcGO, dilatata occurs plentifully in the upper part. The following details, supplementary to those given in the Cambridge Memoir, were noted in 1882. The brickyard north, of Willingham is abandoned, but in one part of the old pit there was to be seen stiff dark grey clay with many crystals of selenite. I picked up one specimen of Gryphcea dilatata, and was told by the man who dug the clay in former years, that many were then found. On showing him a specimen of Ostrea deltoidea, obtained elsewhere, he unhesitatingly said that the fossils he got were of the former kind. A farmer told me that in Over Field, about half a mile north of Long Stanton Station, clay had been dug for making clay-lumps, or sun-dried bricks, used for barns and hovels. I got no definite evidence of Oxford Clay in Willingham Field nor in Hampton Field. Between Willingham Field and The Meadows the soil is a greenish-grey clay, with gravelly patches here and there ; occasionally septaria and fragments of white limestone are turned out of the ditches. Layers of white limestone occur in both Oxford and Kimeridge Clays. Corallian Beds. General Remarks. The presence of rock-beds of Corallian age in certain localities in Cambridgeshire and in Huntingdonshire is a fact of remarkable interestwhen it is borne in mind that elsewhere over alarge tractof country, from near Stanton St. John in Oxfordshire, and Quainton in Buckinghamshire, to Acklam Wold in Yorkshire, these rock- beds are unknown, and that, in their absence, it has been con- sidered that the Oxford Clay gradually passes into the Kimeridge Clay. The researches of Prof. H. G. Seeley have shown that a number of thin rock-beds occur in this united series of clays in Cambridgeshire and Huntingdonshire. Some of these rocks are found low down in the Oxford Clay, but others occur at or near CORALLIAN BEDS. 7 the border-line between the Oxford and Kimeridge Clays. More- over a considerable thickness of clay containing an admixture of fossils belongingto these two formations, and to some extent repre- senting the Corallian Beds, comes between them. First noticed at Bluntisham, and afterwards at Tetworth, the names of Bluntis- ham Clay and of Tetworth Clay were successively applied to this . intervening formation ; but a far better exposure being ultimately seen in the cutting of the Midland Railway at Ampt- hill, the name of Ampthill Clay was adopted for these passage- beds between the Oxford and the Kimeridge Clays.* Among the rock -beds noticed by Prof. Seeley were those at Elsworth and St. Ives, and he considered that the former rock was the newer, and occupied a position at the top of the Oxford Clay, while the St. Ives rock lay below. These views have not been confirmed, indeed palseontological evidence shows that the rocks of Elsworth and St. Ives are on the same horizon, and that they probably represent in time the Lower Calcareous Grit. Among the fossils are Ammonites cordatus, A. perarmatus, Pleurotomaria Milnsteri, Avicula ovalis, Lima elliptica, Ostrea gregaria, Pecten fibrosus, P. lens, &c.f Me. T. Roberts has recently shown that fossiliferous clays, identical with the Ampthill Clay, can be traced through Lincoln- shire, so that it appears highly probable that there is a distinct palseontological representative of the Corallian Beds in those areas of the Midland counties where no rock-beds have been found. He gives the general succession in the Cambridge area as follows : J — Kimeridge Clay, with a phosphatic nodule-bed at its base. Ampthill Clay, with the Elsworth Rock, representing the Corallian. * Oxford Clay. The question of the relation of the Upware Limestone to the Ampthill Clay is not here noticed, but there can be little doubt that the limestone comes above the clay, while the Elsworth Rock is below it.§ Ampthill Clay. This clay is characterised by the presence of Gryphcea dilatata and Ostrea deltoidea, forms obtained at Bluntisham railway- * Ann. Nat. Hist., ser. 3, vol. viii., pp. 503-505 (1S61), and vol. x., pp. 97-110. (1862); Geologist, vol. iv., pp. 552, 553. (1861); Rep. Brit. Assoc, for 1861, Sections, pp. 132, 133. (1862) ; and Index to Fossil Remains of Aves, &c. 1869, p. 109. f Blake and Hudleston, Quart. Journ. Geol. Soc, vol. xxxiii., p. 313. (1877.) t Sedgwick Essay for 1885 (not published), quoted in Quart. Journ. Geol. Sod., vol. xlv., p. 547. (1889.) § See also Prop. Morris, Proc. Geol. Assoc, vol. ji., no. 5, p. 220 (1872), and Prof. T; McK. Hdghes, ibid., vol. viii., no. 7, p. 461. (1884.) 8 CORALLIAN BEDS, cutting by Peof. Seeley. A full list of the j° ss ^ jr ^ given by Mr. T. Egberts.* The beds representing the Ampthill Clay in this district are coloured with the Oxford Clay on the map. Pbop. S™ says of the railway-cutting S.W. of Blun^shan: .that "just below the surface, is found a rock, of a grey-blue colour and un known thickness, which was so hard that t had to be bla sted m laymg the railway drain. I have a fragment, containing iron-shot oohticgraiM ana shells/quite resembling the rock of Elsworth," and from thi i clay he records Ammonites alternans, A. Uplem A., grains [= A XandOslTa excavatusl Belemnites exr,entricus , Gryphcsa, Matata (abundant), andUstrea deltoidea (rare). , , . , _-__ r,fhpr He also mentions that at Over " Belemmtes excentmcus andaome other fossils have been met with, identical with those of Bluntishaun u **"£ Mr. James Carter had a series of fossils "which he believes came from Holiwell," and these indicate the horizon of the Elsworth Jiock.T Coral Bag and Coralline Oolite. Perhaps the earliest mention of the rock at Upware is by C. Vancouver in 1794, who says that "The arable land [of this part of the parish of * Wickin '] consists of a deep brown mould, upon a dry bed of ragstone."J The earliest description of the beds, appears to be by FlTTON, in his classic paper on the Strata between the Chalk and the Oxford Oolite, which was read in 1827.§ His attention was evi- dently drawn to the subject by Sedgwick, || who, in conjunction with Mr. McLauchEan, had formed a collection of fossils from the stone-beds of the Upware quarries. According to Fitton the "Oxford Oolite'" occurs "in a low ridge extending for about three miles north of Upware . . . The stone beds have been opened here in two or three quarries . . . The strata are slightly inclined to the west of north, in a direction opposite to that of the beds below the chalk. The stone here laid bare to a depth of about 10 or 12 feet, consists of a loose rubbly limestone, of a cream colour, in some places coarsely oolitic." He adds, "The coralline beds (the proper "Coral Rag" of Smith) do not come up to the surface at this 'place; but they break out, Mr. Sedgwick informs me, beyond Haddenham, going towards Chatteris ; " but this is a mistake, and Sedgwick makes no reference to it, when alluding to the Upware rock, in 1860 ; indeed he states that " for many miles in the general range of the series, botfi towards the N.E. and the S.W., no traces of this Goraline deposit have been met with."^[ The Corallian beds of Upware are now exposed in two quarries, and were formerly opened up in a third quarry east of High Fen Farm. * Quart. Journ. Geol. Soc, vol. xlv., p. 556. (1889.) t Ann. Nat. Hist., ser. 3, vol. x., pp. 101, 107, 1 10. (1862.) X General View of the Agriculture in the County of Cambridge, p. 134. London. § Trans. Geol. Soc, ser. 2, vol. iv., pp. 307, 31 7, pi. xa. (1836.) || Sedgwick alludes to the Cambridgeshire "Coral Rag Oolite" in 1832 in the second edition of his Syllabus. ^T A Lecture on the Strata near Cambridge . . , p. 22. Privately printed. 1861. CORALLIAN BEDS. 9 ' When mapping this tract in 1880 I noticed traces of the Coralline Oolite to the south of Padney, where it is overlain in places by a thin covering of Drift sand and gravel (with flints, &c). The stone, locally known as " marlstone," comes near the surface a little to the south-west of Padney Farm, and there are indications of what a laboarer said he believed to have been an old stone-pit. . Mr. S. B. J. Skertciily, whose notes were made in 1873, says that "the well at the cottage by the old pit (marked at the junction of the roads east of High Fen Farm) is bricked for about 10 feet down, beneath which a white calcareous-looking rock is seen. The quarry is filled up, and corn now grows upon its site." In the site of this old quarry I picked up (in 1889) small specimens of oolite of the same character as the rock in the quarry now described. The quarry south-west of High Fen Farm, usually known as the northern pit, is now abandoned and partially filled with water. The following description of the beds was written by Mr. Skertchly in 1873 :— " The section on the eastern side of the pit is as follows ": — Soil, full of large oolitic grains about the size of rape-seed and lentils ; 9 inches to a foot. Friable cream-coloured calcareous bed, composed of large oolitic grains in a marly matrix, with iron-shot markings ; and with calcareous nodules, composed of the grains cemented, from the size of a walnut to 3 or 4 inches ; 2 feet 8 inches. Bed like that above, but more clayey, and mottled with iron-stains ; 6 inches. Three courses, about a foot thick, of stone, rather deeper in colour than the upper beds ; 3 feet. Continuation of the stone beds (?) seen in the sides of the cut to a depth of 3 feet. " The stone is very soft, scarcely worthy of the name of stone, large pieces 6 inches thick being easily broken by the hand. It is composed of large oolitic grains and minute shells, encrusted with calcareous matter. The texture is rather open. A few obscure bivalve-shells occur throughout the whole deposit. The beds dip S.S.E. at about 3°. The stone is divided by irregular joint-planes about perpendicular to the bedding, and comes away in irregular lumps from 2 to 6 inches in thickness, and from 1 to 3 feet square." " The northern side of the quarry is very much overgrown, but pre- sented an interesting feature. This was a big patch of Kimeridge Clay, which I drew carefully, commented on largely in my note-book, and found afterwards to have been brought from Eoslyn Hole, Ely, to stop a strong spring that burst out there ! " When I revisited this quarry in 1889 it showed only 8 or 9 feet of crumbly oolitic and pisolitic limestone, reminding me of the Osmington, oolite of Weymouth. Proe. Bonney remarks that the heart of the rock is often greyish blue, and he first pointed out the general distinction between the beds in this and in the southern quarry.* Messrs. Blake and Htjdleston note that at their visit about 12 feet of the Coralline Oolite was exposed, dipping to the south. They mention that JEchinobrissus scutatus and Holeatypus depressus are numerous, while other fossils include Littorina mwricata (var.), GervilHa aviculoides, Opis PhillipsH, &c.f Further south the oolite was shown (in 1880) in several places by the side of the lane leading towards the southern quarry, and by the side of the lane leading from Wicken Lamas Ground towards Fen Side. * Cambridgeshire Geology, p. 17. (1875.) f Quart. Journ. Geol. Soc, vol. xxxiii., pp. 314, 315. (1877.) 10 COKALLIAN BEDS. In the field to the south of this lane I picked up, in 1889, pieces of oolite and also some corals, suggesting that thereabouts the rock shown in the southern quarry (Coral Eag) overlies that of the northern (Coralline Oolite). Mb Skertchly also notes that "Along the road leading towards TTpware from the northern quarry the Coral Eag is seen on the side, at a, somewhat higher level than any bed in the pit (perhaps by 8 feet), and the stone is rubbly, fine-grained and hard, weathering like Combrash. The oolitic grains are small, and casts of coral are sparingly found." The southern quarry is about half a mile north of the inn Five Miles from Anywhere. Here, as Messrs. Blake and Hudleston observe, "the beds dip N. by W., at an angle of about 4°, so as to expose on the whole about 20 feet. Generally described, it is entirely a creamy white but rather irregular limestone, in parts crystalline. It contains, however, several layers of considerable size, composed of Thamnastrcea araahnoides, Bhabdophyllia, &c. Between the more crystalline portions are some more earthy parts, containing abundance of shells, some complete, but others almost rolled into oolitic granules. The fossils in some beds have entirely perished, leaving, however, external casts, with loose internal cast3 inside. The corals and other fossils . . prove this to be the true Coral Eag as we have restricted the term." * In addition to the Corals, spines of Cidaris florigemma, Peaten vimineus, Liilbodomws inclusus, Miller icrinus, &c. have been found. (-! iWhen I saw the quarry in 1889, accompanied by my colleague Me. A. C. G-. Cameron, the section was not very clear, but the rock (a pale cream- coloured oolite, bluish-grey where unweathered) is occasionally worked for road-mending. The Coral-beds with Cidaris, &c. occur in the upper 8 or 10 feet, while the lower beds consist largely of rolled shell-fragments. At the base we observed shelly and oolitic marly limestone, resembling the beds in the northern quarry : thus confirming the view of Messes. Blake and Hudleston that the beds here overlie those seen in the northern pit. Mr. T. Eobbrts subsequently informed me that he had come to the same conclusion. The section given by Messrs. Blake and Hudleston ■}■ (confessedly diagrammatic) shows the Corallian beds with synclinal struc- ture, overlain by Neocomian beds. These latter are shown to extend along the Upware ridge, whereas the Corallian rocks occur there at the surface, the newer beds only appearing as a fringe on the western side of the ridge for a short distance between the two quarries. With regard to the dip of the beds there is much diversity of opinion. On the one hand, Fitton (referring evidently to the southern pit) remarked that the strata are slightly inclined to the west of north, and this view is supported by Messrs. Blake and Hudlesxon, who estimate the angle at about 4°.J On the other hand, Mr. Skertchly says, " The Coral Eag appears to dip towards the fens S. or W., but it is obscure. The angle is from 2° to 4°. There is perhaps an anticlinal, since the beds in the other pit dipped about 3° in a south-easterly direction." In the northern pit the dip is stated by Messrs. Blake and Hudleston to be south ; whereas Prop. Bokney remarks that, so far as there is any, it is northward, probably a little west of north. § Considering the irregularity of the bedding, my own impression is that no trustworthy dip is seen ; but, judging by the thickness of the beds, it seems most probable that one or more gentle undulations affect them. Piiton indeed represented the beds as occurring in an anticlinal,|| and Proe. Bonney has expressed himself in favour of .this view.1T It may also be noted that Prop. Seeley considered there was evidence of an anticlinal in * Quart. Journ. Geol. Soc, vol. xxxiii., p. 314. f Quart. Journ. Geol. Soc, vol. xxxiii., fig. 9, p. 315. j See also Geol. Mag., dec. ii., vol. v., p. 90. (1878.) § Geol. Mag., dec. ii., vol. iv., p. 476. (1877.) || Trans. Geol. Soc, ser. 2, vol. iv., pi. ia, fig. 24. IT Geol. Mag., dec. ii., vol. iv., p. 476. (1877.) CORALLIAN BEDS. 11 the Oxford Clay near St. Ives ;* and this view is supported by Messes. Penning and JuKEs-RROWNE.t Pkoe. Seeley also spoke of a possible syn- clinal between St. Ives and Over. Phot. Seeley, using the name "Upware Limestone," regarded the rook as underlain by the Ampthill Clay ; but we have no evidence of this. He also regarded the Upware rock as a reef.J Messes. Blake and Hudleston ,in speaking of the Coral Rag of the southern pit, state that " The irregularity of the bedding is an indication of its reef-like character, to which, and not entirely to denudation, its termination may be due."§ Prof. Bonney, too, had regarded the Upware rock as " a reef in the generally incoralliferous interval " between the beds in Yorkshire and Oxfordshire.|| The evidence (obtained by Mb. T. Roberts) of the coprolitic band at the base of the Kimeridge Clay is suggestive of some pause, if not of denudation ; but more facts, from borings, &c, are wanted, before it can be decided whether the Upware rock is purely a local accumulation, or whether it has suffered denudation, in Upper Oolitic times, and thus is overlapped westward by the Kimeridge Clay. In 1868 Mr. H. Keeping published a section of the strata at Upware (reproduced on p. 23) showing Neocomian beds, &c. resting on Kimeridge Clay and on Corallian rocks. The Kime- ridge Clay he believed to be unconformable to the Corallian Beds, and he noted a bed of " Coral Rag intermixed with Kimmeridge Clay " as intervening.^ Subsequently his son, Mr. W. Keeping, published another section across the district, and expressed his opinion that the Kimeridge Clay was not unconformable to the underlying rock. He remarked that " for some depth around the present outcrop of the Coral Rag this latter rock has been bared of its covering of Kimmeridge Clay so that the phosphatic bed of the Lower Greensand comes to overlap on to the coral rag. The destructive work of the removal of the Kimmeridge Clay went on during the earlier times of the formation of the Lower Greensand, and one of its results was the production of a curious deposit composed of irregular broken fragments of coral rag mixed up with the clayey material of the Kimmeridge Clay in such a manner that it actually presents the appearance of Boulder Drift."** Mr. Skertchly, in his notes, says " It seems to be as probable that the Cretaceous beds were deposited against the Coral Rag as that they were faulted against it, the form of the ground admitting of both interpretations." * Arm. Nat. Hist., ser. 3, vol. x., p. HO. ■f Geology of Cambridge, p. 6. J Ann. Nat. Hist., ser. 3., vol. viii. p. 504. (1861) ; and Index to the Fossil Remains of Aves, &c. 1869. § Quart. Journ. Geol. Soc, vol. xxxiii., p. 314. || Cambridgeshire Geology, p. 19. % Geol. Mag. t vol. v., p. 273. See also Bonneit, Cambridgeshire Geology, pp. 63-68. • ** Fossils of Upware, &c, 1873, pp. 3, 5. 12 COEALLIAN BEDS. Fossils of the Coral Bag. The following revised list of Corallian fossils from Upware, drawn up for the Sedgwick Essay of 1885 (not yet published) Las been kindly communicated by Mr. T. Roberts, of the Wood- wardian Museum, Cambridge. Lists have been published by Pkof. Bonnet (Cambridgeshire Geology, pp. 18 19) and by Messbs. Blake and Htoleston (Quart. Journ. Ueol. Soc., vol. xxxiii., p. 314, and Oeol. Mag., dec. ii., vol. v., p. 92). N. = from the Northern Pit. S. = from the Southern Pit. Cephalopoda. Ammonites Achill es, D ' Orb . mutabilia, Sow. perarmatus, Sow. plioatilis, Sow. Alaria Oerithium muricatum, Sow. Chemnitzia heddington- ensis, Sow. - Emarginula Goldfussi, Roem. Pissurella eorallensis, Buv. Littorina Meriani, Qoldf. - muricata, Sow. Natica elymenia, D'Orb. clytia, D'Orb. - Neritopsis decussata.Afiiwsi. — S. — S. N. — N. S. Ammonites vertebralis, var. cawtonensis, Bl. and Hudl. Belemnites abbreviatus,.3OT. Gasteropoda. — S. Neritopsis Guerrei, Heb. — S. and Desl. Pleurotomaria reticulata, — 8. Sow. - — S. sp. (oast) — S. Pseudomelania striata, Sow. — S. Trochotoma tornata, Phil. - N. S. Trochus — S. Turbo princeps, Roem. — S. sp. - — S. Lamellibranchiata. Anomia suprajurensis, Buv. Area semula, PhilS- oontraeta, Phil. pectinata, Phil. quadrisulcata, Sow. Astarte aytonensis, Mor and Lye. ovata, Smith : sp. - Oardita ovalis, Querist. Cardium, cf. delibatum Be Lor. Cucullasa elongata, Phil. Cypricardia glabra, Bl and Hudl. Exogyra nana, Sow. Gastrochfenamoreana, Buv Gerviliia angustata, Roem. - avieuloides, Sow. Goniomya v-scripta, Sow. Hinnites velatus, Goldf. sp., cf. corallina, Hudl, Homomya tremula, Buv Isoarca multistriata, Et. texta, Querist. Lima elliptica, Whit. rigida, Sow. - rudis, Sow. ■ sp. Lucina globosa, Buv. N. - S. - S. - s. - s. - s. - s. - s. - s. - s. - s. - s. - s. - s. - s. • s. S.P ■ s. • s. ■ s. ■ s. - s. ■ s. s. s. s. s. s. Lucina moreana, Buv. Modiola bipartita, Sow. cf. rauraciensis, Oreppin subsequiplicata, Soem. sp. - (Lithodomus) inclusus, Phil. - Myacites decurtata, Goldf. - recurva, Phil. Myoconcha texta, Buv. Mytilus ungulatus, Young and Bird Opis corallina, Damon lunulata, Roem. - Phillipsii, Mor. virdunensis, Buv. near to paradoxica, Buv. Ostrea gregaria, Sow. solitaria, Sow. Peoten articulatus, S'eh. fibrosus, Sow. vimineus, Sow. Perna subplana, Pit. Pholadomya decemcostata, Roem. Plicatula fistulosa, Mor. and Lye. Quenstedtia laevigata, Phil. var. gibbosa, Sudl. Trigonia Meriani, Ag. — S. N. — — S. — S- N. S. — S. — s. — s. — s. — s. — s. N. — — S. — s. — s. — s. — s. — s. — s. N. S. — S. — S. N. S. — S. — s. — s. — s. — s. nr. s.p — s. — s. — s. — s. — s. — s. — s. OOBALLUN BEDS. 13 Braehiopoda. Rhynchonella, small Terebratula insignis, var. maltonensis, Oppel. - — 8. j Terebratula, small — s 1 Crustacea. — S Gastrosacus Wetzleri, Meyer — S. I Prosopon rostratum, Meyer — S Glyphea ... Anneli da. — S Serpula ... — S. 1 Vermioularia Echmodermata. 1- s Apiocrinus polycy phus , Bes . Cidaris florigemma, Phil. - Smitb.ii, Wright Oollyrites bioordata, Leske. Echinobrissns scutatus,iaTO. (very common in the upper part of the northern pit) Hemioidaris intermedia, Flem. - ■ - Isastraea explanata, Goldf. - Montlivaltia dispar, Phil. - Rhabdophyllia Phillipsii, Edw. S. — S. s. N. s. N. s. — s. Holectypns depresstis,£esfce (very common in the upper part of the northern pit) Hyboclypus gibberulus, Ag. n. sp. - Millericrinus Paeudodiadema versipora, Phil. . - Pygaster umbrella, Ag. Stomechinus gyratus, Ag. - Actinozoa. — S. — s. — s. Stylina tubulifera, Phil. Thamnastrsea arachnoides, Park. concinna, Goldf. N. S. N. — — S. — S. N. — N. S. — S. — S. — s. — s. Spongida. Scyphia, — S. Kimeridge Clay. General Remarks. The Kimeridge Clay of Cambridgeshire consists of dark grey or blackish clays and paper-shales, with occasional septaria and, in places, many crystals of selenite. PalEeontologically the formation has been divided as follows : — Upper Division. Clays and Shales -j Lower Division. Clays - -\ with Diseina latissima. ,, JSxogyra virgula. ,, Ammonites altemans. ,, Asta/rte supracorallina. . „ Ostrea deltoidea, The lowest four divisions are grouped as Lower Kimeridge by Me. T. Eoberts, who has determined the succession of these zones.* He remarks that a layer of phosphatic nodules occur at the base of the formation, and the clays immediately above are crowded with Ostreo, deltoidea, a fossil that prevails at this horizon in other localities in this country. The beds with * Quart. Journ. Geol. Soc, vol. xlv., pp. 557, 558. (1889.) 14 KIMEKIDGE CLAY. Exogyra virgula are, however, usually grouped with the Upper Kimeridge Clay, and as there is no marked plane of division in the formation, we see no reason to depart from tne ordinary classification. Concerning the full thickness of the Kimeridge Clay m the area we have no trustworthy data. A well-section at Stretham Fen has been thought to pass through 110 feet of this formation ; but it is by no means certain that the clay is Kimeridge Clay ; indeed, judging by the map, it is as likely to be Gault. More evidence is needed of the nature of the clay around Fordey Farm, to the north of the Upware ridge, but I obtained no evidence to modify Me. Skeetchly's original mapping of that tract as Gault. Prof. Bonney says that at Ely the thickness of the Kimeridge Clay is said to be about 60 feet ;t and the Rev. 0. Fisher has stated that a well commenced in this clay at Ely " soon reached the Oxford Clay with a thin stony band contain- ing Nerinma intervening."} It should be mentioned that we have no record of Neriricea from the Upware limestone, nor from the Elsworth rock, though Chemnitzia and other Gasteropods have been obtained. Again, the estimate of 135 feet for Kimeridge Clay at Lol- worth,§ six miles N.W. of Cambridge (Sheet 51, S.W.), cannot be regarded as conclusive, for 'it is mentioned that a bed of rock occurred 30 feet from the surface, and this rock may be on the horizon of that at Boxworth, or near the junction of the Oxford and Kimeridge Clays. Local Details. In 1882 attention was called by Prof. Hughes to the occur- rence of Kimeridge Clay fossils at Balsar's Hill, east of Willing- ham, in a tract previously regarded as Oxford Clay. Early in the spring of that year I examined the area, for the purpose of mapping the Kimeridge Clay, and made the following notes, but did not attempt to distinguish the Corallian clays (Ampthill Clay) which the researches of Prof. Seeley, and more recently of Mr..-T. Roberts, have shown to occur in this district. The first indication, of this clay I obtained in a specimen of Ostrea del- toidea from a drain freshly opened just south-east of the barn (not on the map), about half-way between Cow Common and Balsar's Hill, binding that this Oyster is mentioned from the Oxford Clay,|| I began to think that the evidence was worth little: but Prof. Hughes subsequently informed me that the specimen obtained by Prof. Seeley from the " Oxford Olay " of Boxworth (now regarded as Corallian by Me. Roberts) was a variety of 0. deltoidea. A dyke running in a northerly direction, not quite half a mile west of Balsar's Hill, showed dark blue and grey shaly clay, with here and there * Geology of Cambridge (Geol. Survey Memoir), p. 165. f Cambridgeshire Geology, p. 20. j Geol. Mag., vol. v., p. 410. (1868.) § Geology of Cambridge, p. 162. || Geology of Cambridge, p. 7. KIMERIDGE CLAY. 15 streaks of ochreous matter : small crystals of selenite were abundant, and there were occasional septaria. Prom the clay (in place) I got several large specimens of Ostrea deltoidea ; and a number of other fossils and " coprolites " were found in heaps of clay thrown out of the ditch. Here and there very thin traces of gravelly or sandy soil occurred ; but there could be no doubt from the character of the fossils and from their state of preservation, that they came out of the clay. Small black " coprolites " were numerous : they are noted on Me. Peming's working map in several places. My belief is that they belong to the Kimeridge Clay, and Mr. T. Boberts informs me (1889) that he regards the coprolitic band as the base of the Kimeridge Clay. I took them directly out of the clay in the banks of the dyke, and fossils are found attached to them. On a second visit, with Prop. Hughes, he obtained (and carried off) a specimen to which was attached a specimen of Exogyra nana, a shell somewhat abundant at this locality. The fossils found here are entered in the list on pp. 18, 19. At Balsar's Hill there is an old camp. A ditch was excavated in bluish- grey clay with a band of hard and compact limestone ; the beds yielded frag- ments of Ostrea, and one perfect specimen of Ostrea deltoidea, which Prof. Hughes unearthed. The spot where he first noticed Kimeridge Clay fossils was in a ditch running at right angles to the ditch (previously mentioned) in which I obtained most of my fossils. About a quarter of a mile to the north, and S.S.E. of Balsar's Hill, a ditch (in course of construction) showed a layer of pale grey and cream- coloured limestone, in some places hard, in others soft and earthy. In a shallow pit, nearly full of water, to the south of Cow Common, beneath a sandy and gravelly soil, there was a calcareous deposit, that looked much like debris of Coral Rag. Beneath this, clay had been dug for the manufacture of clay-lumps. Calcareous matter, however, is common in the gravels of this district.* There is a tolerably well-marked feature, which was adopted for the boundary-line of the Kimeridge Clay between Willingham and Balsar's Hill. There appears to be no reason for a feature, but as the Oxford Clay occurs at the old brickyard north of Willingham, and the Kimeridge Clay occurs on the rising ground to the east, the safest place to draw the line is at this feature. How far to the south the Kimeridge Clay may extend I am at a loss to say, there was no evidence of one thing or another east of Willingham Pieid and north of Kampton Pield.t A trial-boring at Eampton (probably near the church), is recorded as in Oxford Clay. If the coprolites truly belong to the Kimeridge Clay, and if the spots marked as yielding coprolites, on Mr. Penning's working-maps, indicate coprolites in place, then the line for Kimeridge Clay ought to be drawn much further south. On the other hand, the coprolites may in many places be surface-specimens, the relics of an eroded Kimeridge deposit, or coprolites of newer ages. I picked up one specimen of JSscogyra virgula, but it was in soil turned out of the pit south of Cow Common. The large pit at Roslyn Hole, Ely, affords the best section of the Kimeridge Clay in the district. Here the clay has for a long period been dug for mending or tamping the banks of the Pen-dykes. Many remains of Saurians and of Pishes have been got from this pit by Mr. Marshall Pisher, of Ely (see Notes by Mr. E. T. Newton, pp. 16-18). Among other fossils recorded are JRhynchonella inconstans and Ostrea deltoidea, suggestive of the lower beds of the Kimeridge Clay, and Ammonites bi/plex, Gardium striatvlwm, Discina latissvma, &c. suggestive of the higher beds. Prof. J. P. Blake says: "At Ely very little is seen of the Upper Kimmeridge ; for although not more than 32 feet of strata are exposed, the upper portion is papery and bituminous, and contains Lucina minus- * Geology of Cambridge, pp. 90, &c. t Geology of Cambridge, p, 168. 16 KIMERIDGE CLAY. cula, Biscina latissima, Carclium striatulum, with other fossils ; while below the more clayey beds contain Amm. serratus and other species characteristic of Lower Kimmeridge, Exogyra vvrgula forming a whole band intermediate between them and going up into the shales. * Mr. Skertchly took the following measurements of the Kimeridge Olay in the south-eastern corner of the great pit in 1874 : — Feet. Clayey soil - - - - - ' . ' Light-blue clay, with ferruginous stains and patches of a white friable material - - - - -2 Ochreous band, mixed with tough blackish clay ; 2 inches. Laminated, light-blue, rather tough clay, _ with brown mottling, and with much of the white material (as above), Exogyra virgula, and other shells - - - - 2 Dark blue, finely laminated, soft clay, breaking into very small fragments, full of fossils - - - - 3J Lighter-coloured, more compact clay, divided by joint- planes into trapeziform fragments - - 2J Layer of septaria, very large, elliptical, with a tendency to form a bed (one mass measured 3J X 3 X 1J feet)- - 14 Olay, like the above, but not so compact - - li Ochreous layer, with Exogyra virgula, 2 inches - - 1 t Light-blue clay, like the above * ,, - - > a fDark blue clay,, full of shells „ - - J Lighter-blue clay ; Exogyra virgula very plentiful - - 2 Ochreous layer, an inch. Clay, like the above - - - - - 1 Layer of septaria, like the one above - - 14 Section hidden at the bottom for - - - - 10 Lower beds, however, were seen to the west, but were not measured. Mr. Skertchly also noted that " at the southern end of Thorney Hill there was a good pit-section, in 1874." Fossils. Notes on Mr. Marshall Fisher's Collection of Vertebrate Fossils, at Ely, obtained from the Kimeridge Clay of the neighbourhood, and chiefly from Roswell Pit. By E. T. Newton, F.G.S. This collection comprises a large number of vertebrae and limb-bones of Ichthyosaurus, Plesiosaurus, and Pliosaurus; besides other Reptilian and Fish remains. An endeavour has been made to determine the species to which some of the Enaliosauria belong, and more especially to correlate them with the species given by Prof. J. Phillips.J Much information as to the characters of the pectoral and pelvic arches are given by Mr. J. W. Hulke in his address to the Geological Society ;§ but one is forcibly reminded of the difficulty, not to say the impossibility, of determining the species to which separate parts belong. * Quart. Journ. Geol. Soc, vol. xxxi., p. 201. (1875.) t There is a little doubt whether the thicknesses of these may not be meant for feet instead of inches. J Geology of Oxford. 8vo. Oxford, 1871. § Quart. Journ. Geol. Soc, vol. xxxix., Proc, pp. 44-64. (1883.) KIMERIDQE CLAY. 17 Many of the vertebrae have been obtained in series, and evidently represent a number of different species. The limb- bones are of various sizes, and some of them agree in form with those of described species. The largest of the limb-bones is 38 inches long and 1 5 wide at the distal end ; probably it was two inches wider when perfect. Some large peetoral and pelvic bones are likely to be of assistance in elucidating the structure of these parts. One example includes what appear to be the two coracoids and two precoracoids, as well as parts of the scapulae and a limb-bone. This specimen agrees very closely with Mb. Hulke's figure of the shoulder-girdle of Pliosaurus but has the hinder ends of the ooracoids more expanded laterally, the two together having a width of 25 inches, the length of the specimen being 28 inches. The greater part of the coracoids and of the pre- coracoids are preserved, but the processes of the scapulse are broken off. The limb-bone preserved with this specimen somewhat resembles Phillips' figure clix. There are many teeth of Pliosaurus, some as large as those of P. macro- merits, Phil (=P. grandis, Owen), others much smaller, which probably belong -to a second species, and may be P. Irachydeirus. The genus Steneosaurus is apparently represented by two or three scapulse, two femora, and some teeth. The femora are of two very different sizes, and probably belong to two species. The carapace and plastron of a large chelonian, which in its present broken condition measures 16 inches from side to side, is probably the Enaliochelys of Pkop. Seeley. Several large crocodilian teeth, mostly without fangs, and from 2 to 3 inches long, have the enamel smooth or finely granular, with a strong Bharp keel up each side, which, when perfect, is seen to be finely serrated. ■ All these teeth are lozenge-shaped in section ; but some are much more- rounded than others, and the points have in many cases been worn off during life. These teeth doubtlessly belong to Dacosaurus, (now referred to Geosaurus, Plieninger*), and under some of them I found a piece of paper with the following pencil-note : — " A new species of Dahosaurus, hereafter to be named Dakosaurus Fisheri (Seeley), a kind cf crocodile allied to Teleosauriw, and to this animal belong the smooth teeth with a ridge on each side." This seems to be the form since called B. lissocephailus by Pkof. Seeley, and now referred to Geosaurus maximus. A very ponderous ungual phalanx, 7 inches long, has a label giving it the name of Gigantosaurus megalonyx. The remains of Pishes in this collection are not numerous ; but some of them are interesting. Ganoids are represented by a lower jaw of Gyrodus and by some Lepidotus scales. Elasmobranchs (Sharks) are represented by Asteracanthus ornatissimus , of which there are several dorsal defences. There are a few spines of Hylodus acutus, some isolated teeth, and a very- large example of the Hybodont defence, so long known as Sphenonchus ; the base of this specimen is about 2 inches long and 2 wide, the external enamelled part is broken, and consequently one can only judge of its size by the extent of the part which remains, but this is very stout and shows that the external defence must have been large. There are two large dorsal spines of Hybodus, which differ from those of any known species. The most perfect one has both ends a little broken ; but in its present condition it is 12 inches long and about 1J inches wide at the thickest part. The basal groove extends rather more than half the length of the spine. The sides of the exposed portion are ornamented with somewhat irregular, longitudinal ridges, broken up and_ varying in size, between which there are smaller and more irregular ridges. One strong ridge, extending along the anterior margin, forms a definite keel. The distal part of "the posterior border is, as usual, furnished with strong * Lydekher. Cat.JFoss. Rept. Brit. Mus., pt. ii., p. ix. 1889. U 63615. ]? 18 KIMERIDGE CLAY. denticles. I would Buggest that this species be called Hybodus Fisheri, as a mark of respect for its owner, who has for so many years most zealously collected vertebrate fossils from the Kimeridge Clay of Ely. In the following list of Fossils from the Kimeridge Clay of Cambridge- shire C. = Cottenham, E. = Ely, K. = Knapwell, W. = Willingham, The authorities are as follows : — (1) J. F. Blake, Quart. Jown. Geol. Soc, yol. xxxi., pp. 201, 217-222. (2) T. G. Bonney, Cambridgeshire Geology, p. 20. (3) Geology of Cambridge, p. 10. (4) T. Boberts, Quart. Joiwn. Geol. Soc, vol. xlv., p. 558. (5) G. Shabman and E. T. Newton. (6) B. Lydekkek, Catalogue of Fossil Beptilia, British Museum, Parts 1 and 2, 1888, 89. Beptilia. Cimoliosaurus (Plesiosaurus) trochanterius, Owen (P. macrodeirus, Seeley, Colymbosaurus mega- deirus, Seeley) - Geosaurus maximus, Plien. (Dacosaurus lissoce- phalus, Seeley) . . Gigantosaurus megalonyx, Seeley (MS.) - Ichthyosaurus chalarodeirns, Seeley (MS.) - hygrodeirus, Seeley (MS.) - " trigonus, Owen Metriorhynchus P - Peloneustes a^qualis, Phil. (Pliosaurus sterrodeirus, Seeley) - - ... I Pliosaurus brachydeirus, Owen (Plesiosaurus) brachyspondylus, Owen- macromerus, Phil. (P. grandis, Owen) - — nitidus, Phil. .... Steneosauvus Thallasemys Hughii, Biiiimeyer (Enaliochelvs chelonia, Seeley) - Asteracanthus ornatissimus, Ag Ditaxiodus impar, Owen - Eurycormus grandis, A. S. Woocko. Gyrodus sp. (umbilicatus p, Ag.) - sp. - Hybodus acutus, Ag. . Fisheri, Newton (n. sp. see above) (Sphenonchus) - Ischyodus - - Lepidotus --.__! Leptacanthus P .... Macropoma substriolatum, Huxley - - '. Cephalopoda. Ammonites alternans, von Buch. - biplex, Sow. - calisto, D'Orb. - cordatus, var. excavatus, Sow. (A. ser- ratus, Sow.) - eudoxus, D'Orb. longispinus, Sow. ... mutabilis, Sow. Aptychus (Trigonellites) latus, Parle. Belemnites abbreviatus, Mill. ■ explanatus, Phil. E (1, 5, 6). E (1, 5, 6). E (1, 5). (1, 6). (1, 6). E (5, 6). (6). (1, 6). E (1, 5, E (1, 5) E (5, 6). E(5). E(5). 6). - (1). C, E (2, 5). E (2), Wilburton. E E'(2). E(5). E(5). E(5). E (2, 5). E(2). E (2, 5). E(2). E (2), C. E (4), W (5). E (1, 2), K (3). E(2). E(l). E(2). E(2). K(3). E(2). KIMERIDGE CLAY. 19 Gasteropoda. Dentalium Quenstedti. Blake Lamellibranchiata. Area minuscula, Cont. rhomboidalis, Gont. Astarte ovata, Sow. ; supracorallina, B'Orb. Avicula aadilignensis, Blake costata, Sow. echinata, Sow. ; — inascmivalvia, Sow. - Cardium striatulum, Sow. ' - Cucullsea (Area) contracta, Phil. Exogyra nana, Sow. — virgula, Befr. Grastroohsena ? Lucina minuscula, Blake Ostrea deltoidea, Sow. gregaria, Sow. Pecten Grenieri, Gont. lens, Sow. Trigonia clavellata, Park. - Pellati, Mun-Ohal. (1). (1). (1). E(4). (1). W(5). K(3). E(2). E (1, 2). E(2). E (2), K(3), W(5). E (1, 2, 4). W(5). E(l). E(2,4),K(3),W(5). E (2), K (3). (1). (1). K(3). (1). Braehiopoda. Discina latissima, Sow. - - - E (1, 2). Lingula ovalis, Sow. - - - E (1, 2). Enynohonella inconstans, Sow. - - E (1, 2). Crustacea. Pollioipes Hausmanni, Koch and Bunk. - (1). Cytheridea Euperti, Blake (MS.) - - (1). triangulata, Blake (MS.) - (1). Cythere ffiqualis, Blake (MS.) - - (1). Annelida. Serpula tetragona, Sow. variabilis, Sow. Vermilia sulcata, Sow. Vermioularia contorta, Blake (1). W(5). W(5). E(l). Echmodermata. Ehabdocidaris maxima, Goldf. E(2). Fora/mini/era. Cristellaria Isevigata, B'Orb. Marginulina gracilis, Com. lata, Com. Planularia strigilata, Beuss. Vaginulina harpa, Boem. - striata, B'Orb. - (D- (1). (1). (1). (D- (1). B 2 20 CHAPTER III CRETACEOUS BEDS BELOW THE CHALK. Lower Greensand. In the western part of our district the Lower Greenland occurs in a number of small tracts, of which four are outliers, whilst the six others, though separate as outcrops, probably join on to each other beneath the Fens, and also to the main mass south of the Ouse-marshes. The formation is, however, so thin that possibly it may be cut out in places, by the Gault over- lapping on to the Kimeridge Clay, near Barraway being a likely locality for such an occurrence. The Lower Greensand consists of sand, brown and light- coloured, but rarely green, with sandy clay ; the only point of interest perhaps being the occurrence of rolled phosphatized nodules and . fossils (derived from Jurassic beds), which have been worked in several places by the edge of, or just beneath, the Fens. Main Mass. The outcrop on the south of the Alluvium of the Ouse has already been described, in the Cambridge Memoir. The nearest point to this at which the Lower Greensand was seen was at some coprolite-workings, under the fen on the southern bank of the Ouse about a fifth of a mile below Stretham Ferry Bridge ; but there was no good section at the time of my visit, in 1882, when I was told that coprolites had also been worked a little to the S.W. In a ditch on the north I saw a little peat, &c, not over 2 feet thick anywhere and often less, resting on light- coloured Kimeridge Clay. Close by, to the south, the Lower Greensand comes on, beneath the Alluvium, in hollows, and consists of clayey sand and very clayey green- sand, with the nodule-bed, up to 9 inches thick. There were pieces of iron-sandstone as well as of sandstone. The owner told me that he had sunk to a depth of 10 feet here. The irregularity of the junction with the Kimeridge Clay was shown by this clay occurring in sharp humps : Ammonites biplex was common in it. Another old working, on the northern side of the river nearly a mile N.E. of the bridge, had, I was told, extended over seven acres, to a depth of 2 fnet ; but, as ..the Kimeridge Clay seems to crop out all round, this would seem to have been merely in a set of pipes, or in a sheet of nodnles left from the erosion of the Lower Greensand. An old working was seen, on the northern bank of the river, about three quarters of a mile below the bridge, and, at an earlier date, Mk. Skektchly saw another about an eighth of a mile further. Up to this point no Lower Greensand has been shown on the map ; but from here (southward of Stretham) there is a small outcrop, by the side of the left river-bank, for less than a quarter of a mile. I mapped this little patch in 1882, but with some doubt, the boundary being taken from a slight rise of the ground. There is sandy clay about, and the nodules have been worked at the western end. On the other side_of the river a low mound rises from out of the Alluvium, eastward from Mere Mill, forming an island in the marsh, with a loamy soil. On the river-bank, at the north-western part, green sandy clay was seen, and at the north-eastern, sandy clay. LOWER GREENSAND. 21 Mr. Skeetchiy saw a coprolite -working by the left side of the Ouse just below Stretham Common, and he has left the following note of one "near the confluence of the Ouse and the Cam, close to the former," taken in 1873 and partly printed in the Fenland Memoir, p. 253 : — r Peat, 2 to 3J feet. Alluvium - < Light-blue and brown sandy loam, with roots of reeds, L &c, 24 feet. Lower Greensand. Coprolites in a sandy matrix, appearing as a fine gravel, about 1$ feet. Blue Kimeridge Clay. A note, by the same observer, a year later, of coprolite-workings south of Thetford, referring either to the above or to a neighbouring section, gives the peat a thickness of 4 feet, the underlying light-blue clay, with carbonaceous markings, one of a foot, and the nodule-bed of about 20 inches. The last bed, like the others, was crowded with fragments of roots, with which vivianite (blue phosphate of iron) was plentifully associated. From this part the Lower Greensand rises up westward, from beneath the fen, and forms a long spur, over the higher ground, by Stretham, Wilburton and Haddenham, to Aldreth, which is the largest area of the formation in our district, there being but little capping of newer beds. Phosphatic nodules occur along the border of the fen, and the following notes were taken by Me. Skebtchly in 1874: — " Just west of Plantation House, east of Stretham, dark brown fine sand, with pieces cemented into hard masses, was seen, in 1874 ; but the section was obscure. Though phosphatic nodules were dug close by but few were seen in the sand here. There is a stroDg spring, and two hollows seem to indicate old sand- pits." " The excavations for the phosphatic nodules were closed, and no trace of them could be made out. Some mounds of the sortings were lying in the farmyard, and the material was seen to consist of pebbles (quartzite being abundant), many fragments of ironstone and pieces of the fine con- glomerate caused by the cementing together of the pebbl'es. The shining black siliceous pebbles so characteristic of these beds were in plenty, as •also rolled Brachiopods and fragments of Ammonites. Some of the pebbles were embedded in clay, mottled blue brown and purple." In 1882 I saw an old nodule-working at the southern end of the little spur of the formation south-westward of the House, and Mk. J. J. H. Teall has given the following section of a working at Stretham *: — Sand and pebble's (Drift), 4 feet. r Lower f ^ ooae sand, 3 feet. Greensand 1 1 Hard sandstone ". 2 fe et- ixreensand.j |_ Copr^e.-^,!, The following section, from the same authority, must have been in Wilburton, the place next, westward of Stretham, though described as " at Haddenham, one mile to the west of Streatham" : — . TLower f £i g nt - brOTm sands, 6 feet. P • r\ 1 1 Small pebbles and nodules, 6 inches, reen ana.j ^ g ail ds, more or less indurated, 4 feet. Kimeridge Clay. Of a pit half a mile S.B. of Haddenham Church, Mr. Skeetchly gives the following note, written in 1874 : — " Pine, clean yellow sand, irregularly bedded and finely current-bedded, was dug, in 1874, to the depth of about 15 feet. In some of the thinner * The Potton and Wicken Phosphatic Deposits, p. 24. 8vo. Cambridye and London, 1875. 22 LOWER GKEENSAND. beds a few small pebbles occurred, and there was one regular continuous pebble-bed. At the base the sand was pebbly and cemented into a soft grey conglomerate. Throughout concretions of ochreous matter occurred, which, on the surface and in rabbit-holes, formed stalactitic masses, adhering to the sides. About 8 feet from the top was a layer of blue clay, about an inch thick, and ferruginous matter formed a continuous band, a quarter of an inch thick, both above and below this. There seemed to be a very slight north-easterly dip, not more than half a degree. The Kimeridge Clay seemed to be about 10 feet down, judging from a well at the bottom of the pit." By some slip Pbof. Seeley has described the Haddenham mass as Upper Greensand.* Turning now to the right, or eastern, bank of the Cam our most southerly outcrop is both very short and very narrow, yet this small piece of the western flank of the gentle TJpware Ridge is of great interest, for here the Lower Greensand, which has been laid open in coprolite-workings, is banked against the Coral Rag at the surface, the two being separated by only a very small amount of Kimeridge Clay, westward of the Coral Rag outcrop. This small outcrop has a considerable literature, and, as the sections have been for some time abandoned, we must depend chiefly on published accounts, as indeed Me. Teall was obliged to, before 1875. The first observer to describe these sections was Me. J. F. Walker, from whose paper the following remarks are takenf : — "The workings are situate about a mile from TJpware'' . , r.lf.l "The bed differs from the "Sandy conglomerate bed," in being'less ferruginous, and containing more lime, probably derived from the Coral- line Oolite. The nodules are mixed with pebbles . . . about a third part is waste. . . The sections exposed by the workings differ con- siderably ; the best I have seen was " . „ Ft. In. Black peaty soil, often with bones of red deer, horse, &c. Light-coloured coprolites Sand, called silt by the workmen Dark coprolites ... Silt .... Dark coprolites - Clay, not pierced [Kimmeridge (p. 310)]. " At another working " — Sand - ... Coprolitie vein ... Conglomerate (hard rock) Light-coloured sand and clay. " The three layers of nodules noticed in the first section often become blended into one, but the top layer differs in the nodules, being of a much lighter colour, and . . . less valuable." "The hard rock (conglomerate), consisting of nodules and pebbles cemented together by carbonate of calcium, varies considerably, some- foUowutg P^'' T0] - "" P ' 53 °' (1865 ° R, ' ght,y M L ° WCT Greensana on the t Geol. Mag., vol. iv., pp. 309, 310. (1867.) - 1 6 . 1 - 1 6 - 9 . 1 6 - 1 - 6 - 2 - 4 LOWER GREENSAND. 23 times being so firm as to be penetrated with difficulty ; at other times the coprolites near the clay are easily worked . . Among the nodules there are found phosphatic shells . . They consist of fragments of Ammonites, (and some of the nodules are marked by impressions of Am- monites) casts of brachiopoda, conchifera and gasteropoda, also remains of large Belemnites and Gryphcea dilatata, composed of carbonate of calcium, occur, derived from the Oxford Clay." In a short later account Me. Walker notes that "the shells, &c., proper to the deposit are found more abundantly at the base," and that " most of the sponges that occur at Farringdon are found in this deposit."* In the following year Mr. H. Keeping gave some further particulars, f and for Inspection, Kg. 1, we are indebted to the courtesy of the Editor of the Geological Magazine, Dr. H. Woodward. Our author says, believing that Gault occurred, at a short distance from the outcrop of the Coral Bag, " I sunk a pit. After passing through about seven feet of clay I came to a phosphatic bed, from which I collected the following fossils, proving, I believe, the whole to be Gault " : — (Ammonites inter ruptus, Amm. serratus, Baculites, Belemnites attenuates, B. minimus, Dentaliwm ellipticum, Nucula ovata, N. pectmata.) " The pit was sunk about ten feet in depth." . . " It will be seen from the section (fig.) that the Kimmeridge Clay is unconformable to the Coral-rag ; and it would appear that, at the time of the deposition of the Kimmeridge Clay, a quantity of its [= Cor. Rag] broken and often rounded fragments became intermixed with it " [= Kimeridge Clay]. Fig. I. Section north of Upware. (H. Keeping.) Gault. {! . Non-fossiliferous Gault, 7 feet. Phosphatic bed, averaging 5 inches. Non-fossilferous Gault, about a foot. Lower Greensand. f g. Upper layer of Lower Greensand (after 2 feet in Lower Green- j sand water stopped the work) . I /. Upper phosphate-bed of Lower Greensand. ■I e. Lower Greensand, with few or no fossils. d. Lower phosphate-bed of Lower Greensand, rich in fossils, often cemented to hard conglomerate, and with many derived fossils. c. Kimmeridge Clay. T b. Coral Rag mixed with Kimmeridge Clay. Extends as high up Coral Rag. ■! as the deposit marked h, though not so shown in the figure. [ a. Coral Rag. Some years later Prop. Bonney gave an account of the sections here, from which the following description is takenj : — * Lycett's Monograph of the British Fossil Trigoniae, no. iii., p.; 145. Palaonto- graph. Soc, 1875. t Geol Mag., vol. v., pp. 272, 273. (1868.) j Cambridgeshire Geology, pp. 64-67. 8vo. Cambridge and London, 1875. 24 LOWER GREENSANE. " An excavation which I examined in 1871, a short distance from Coral Rag pit, gave the following section ": — the Ft. Q In. 6 10 Top earth - ... Brown clay, probably re-arranged - Phosphate bed, probably washings from Gault and Neocomian beds fClay, with large fragments of fossil | wood - J Phosphate bed. The clay below this, *> in Mr. Keeping's section, missing, or not distinguishable from the bed below ... 'Clayey sand - - - - Phosphate bed ... Sand - . - - - Phosphate bed and conglomerate. Not exposed, but described by the workmen - 1 3 [•Sand. " The following year, a short distance more to the north, and rather higher up the slope — that is nearer to the terrace of Coral Rag — I saw the following section " : — Gault. Neocomian [Lower Greensand]. L - 4 10 5 6to7 Sandy soil. -1 [Gault.] I [Lower Greensand]. f Gault. Clay, with uneven base Passage bed. Clay mixed up in | J - most complicated manner with ^ About 5 feet, pebbly and clayey sand, base j very uneven -J vr . fSand, at thinnest, about 15 inches. ™ ru,ul:,n J Phosphate bed, 4 to 6 inches. 1 Sand, 15 inches. ' L Phosphate bed and conglomerate, forming floor of pit. ' ' In another cutting about five yards off the Gault was rather more distinct from the clayey sand. It contained phosphatic nodules, and many characteristic fossils. Thi3 section appears to show that the pas- sage from the sands of the Neocomian to the clay of the Gault, was marked by much local erosion." " Again, in the year 1873, at a working about 200 yards north of the Coral Bag pit, and only a short distance from the lane (by side of which this rock seemed to be exposed in a ditch), I observed the following section " : — Ft. In. Rather sandy soil ...... about 2 Gault. Clay, with phosphate nodules, base irregular. Frag- ments of Ammonites, 2 species of Belemnites, Inoceramus concentricus, Plicatula, and JSfeithea, - v - at most about 2 'Clayey brown sand Pebbles (some subangular), mostly of dark ferruginous sandstone (Neocomian), with occasional fragments of limestone (Coral Rag P), 8 to 18 inches Yellow sand, less clayey than that above Phosphate bed ; the nodules mixed with small pebbles of various rocks (ehiefly of a brown chertyrock); from 8 to 12 inches, but irre- gular - - . . . Yellow sand, forming the floor of the pit. The workmen exposed and described the beds below --.... Conglomerate, few phosphate nodules - l_Black phosphate nodules Dark clay, like Kimeridge Clay, Neocomian [Lower Greensand], about 6 LOWER GREENSAND. 25 The author then draws the following conclusions : — The Lower Gault, with phosphate-nodules at its base, is in place, and its junction with the Neocomian is an unconformable one. " The Kimmeridge Clay comes just below the lower [of the nodule- beds] so that the whole thickness of the Neocomian . . . does not exceed about eight feet." "The Kimmeridge Olay must have formerly rested upon a most irregular base of Coral Rag, the surface of an old reef, and was denuded before the deposition of the Neocomian beds : so that in all probability a portion of the reef, which had been buried under a considerable thickness of clay, was again laid bare, as the level of the top of the clay which yet remains is rather below the top of the Coral Rag." " The re-appearance of the Lower Gault on the west side of the reef is probably due to the flexure which has caused the dip of the Coral Rag ; but I think that the dip of the Neocomian beds is partly one of original deposition." Prop. Bonnet then says that "the Neocomian fossils [.seep. 31] are mainly confined to the lower phosphate bed, and I am inclined to think are rather local in it. The calcareous cement is derived from the neigh- bouring Coral Rag. . . . The abundance of terebratula with its allied forms and of sponges . . . suggests the probability that they clustered about the old reef, as the brachiopods, &c. now do on the Australian coast." The same year Mr. Teall referred to the sections,* and gave the following further particulars : — " The nodules are of two colours, light and dark ; the former resemble those of Potton, the latter are characterized by a smooth exterior and a smaller percentage of phosphate. All the black nodules are bored by Modiolae, and most of them are portions of derived fossils. As at Potton we frequently find ferruginous sandy nodules containing casts of fossils, which seem to have been derived from Neocomian strata." . . . " The included pebbles are very similar to those at Potton. ... I take it that many of these pebbles have been derived, as pebbles, from pre- existing Neocomian strata." . . . " The indigenous fossilB . . . are abundant, and are preserved in calcite." Nearly " all the ferruginous shells of Potton are found in calcite at Wicken [= Upware]. This fact, taken in connection with the stratigra- phical relations ... is quite sufficient to prove the approximate con- temporaneity of the two deposits." . . . " The sponges are all of Farringdon species." " In general, then, we conclude that the Potton and Upware beds are the equivalents of the Folkestone beds of the south of England." In this essay a list of the derived fossils is given, some of these being from older Neocomian beds, but most being of Jurassic origin. Mr. Jtjkes-Browne, who saw the section with Prop. Bonney in 1871, and again in 1874, Bnggests that the clay at the top, in which no Gault fossils were found on either occasion, may have been an interbedded mass in the Lower Greensand ; for like clays occur in the Lower Greensand between Thame and Aylesbury, some of which were formerly taken for Gault. In 1877 Prop. Bonney remarked that "at the present time there is a considerable patch of the base of the Gault laid bare, just west of the south end of the [southern] Rag-pit, and perhaps four yards below the crest of the limestone."t * The Potton and Wicken Phosphatic Deposits, pp. 12-15. (1875.) f Geot. Mag., dec. ii., vol. iv., p. 476. . . 26 LOWEK GREENSAND. In 1873 Ma. Skektchly made the. following notes (now first printed) of the section of the ooprolite-works, but without marking the precise spot : — Feet. Peaty soil ... - 2 [Gault?].— Yellow clay - 2 f Greenish sand - - 3 [Lower 1 g™velly bed " Greensand.]^, Co p rolit ;. bed [ 1 3 3. 4 - 1* LSand - over J "More to the north clay [Kimeridge] was touched beneath the coprolite. bed. The men said that to the south they found white stone, full of coprolites, at the top, and they described this bed as being like that in the pit [Rag-pit]. At the spot in question fragments of this rock were lying about, and consisted of unmistakable Coral Eag, with black coprolites of the ordinary character. Can it be a reconstructed bed? Was it in place ? Do coprolites occur in the Coral Eag ? In the last case it would be a remarkable coincidence that they should abut against the Cretaceous coprolite-bed ; and I incline to the opinion that the deposit is reconstiucted, the oolitic grains, &c. having been washed into the coprolite-bed and. then cemented together." The latest account of these Upware sections was written by the late Mr. W. Keeping, from whose book some remarks will now be taken.* As noted by this author his section, which is here reproduced, is in the main similar to that of his father, given above, p.' 23, and the same reference-letters have therefore been adopted here for all the beds. The Lower Greensand has also been found in coprolite-workings beneath the Fen eastward of the Upware ridge. Mk. W. Keeping noted the following section in 1879 as at " new pits close to a farm some 500 or 600 yards east of the Spinney Abbey Farm."t {Brown surface-earth ; 1£ feet. Head of blue clay ; 9 inches. Irregular gravelly bed, pebbles mostly flints and coprolitesj 3 inches. Blue, yellow, and coarsely mottled clay, with scattered coarse grains of quartz, ironstone, &c, and many irregular nodules of coarse ferruginous sandstone and some fibrous wood : passes down into the next ; 2 feet. Brown and yellowish sand, passing into sandy clay, rather coarse and loose : consists chiefly of grains of quartz and of ironstone, with a few ferruginous nodules : passes down into the next ; 2 feet. Phosphatic nodules and pebbles of Lydian stone, chert, quartz, &c, in loose iron-coloured sand: some fer- ruginous concretions in the upper part ; 2 feet. Phosphatic nodules, darker than those above, in a sandy matrix, hardened almost to a rock by carbonate of lime • 3 inches. ' Corallian. Hard grey gritty bedded limestone, with scattered laree oolitic grains. 6 Lower Greensand. * The Fossils and Palasontological Affinities of the Neocomian Denosits nf Upware and Brickhill. 8vo. Cambridge, 1883. (pp. 3-7.) deposits ot t The Fossils . . of . . Upware, &c., pp. 7, 8. (1883.) LOWER GREENSAND. 27 Is ,hto TO S g§8g tj-P-.o-go,^ 5 E5 g <=■ 8,0-0 |S I* »S S I |§tH| H "i.|:s i s : s , ps^ 5> fD o «■ m. P" CJ h-i P- o w m.- MffD2M*--E^O^ * tncn If ?L S ^ EL- * * _ <8 5j Si ttS.|3|8 g B' S O < w ,8 TO B §r§o I §- H " re ".T^ • C! - P) Pj Ml - Hf s g B re 2 W re B'g »,o re a rep* b a re N P ~ p-g o ct> r4**-" O co fO CD CD * a £ g'B CD TO.Q B E. » H re H = © crq cr c+ ET CD cs is O 5- C3 C6 n £ o § Mi a «■*■ & re a> > & c S- a 3 s >-h> 3 cr O W W> M P w \r •n 2! JQ W v ' a c K 28 LOWER GREENSAND. As to the clay next above the sand, although Mk. Keeping had "no hesitation in referring this bed to the Lower Greensand," yet ( there may be a possibility of its being Gault, which seems to have been found else- where, judging by my recollection of sections seen, and by the next note. In 1880 and 1881 Mk. H. B. Woodward noted the following section, nearly half a mile north-eastward of Spinney Abbey, at the only pit then open : — • Alluvium{a-^}3to4feet. Ganlt. Pale greenish or bluish clay, with " race ;" 3 to 4 feet. Lower Greensand. Brown pebbly gravel and sand. Phosphatic nodules make up about half of the stones ; amongst the rest are ironstone, calcareous conglomerate, Lydian stone, quartz, and grit ; 2 to 3 feet. Eastward of Ban-away the Lower Greensand rises up from beneath the Pen, and caps the Kimeridge Clay, forming, with a little Gault and Boulder Clay, Haney Hill. Me. Skertchly noted, in 1874, that " four chains west of the bridge over the Soham Lode at Haney Hill light- reddish-brown fine sand was seen, by the side of the road, to a depth of 4 feet, and further westward [north-westward ?], opposite the road to Barraway, a like section occurred." He thought that the sand seemed to end abruptly, against Kimeridge Clay, in the Soham Lode, as if faulted, and he was inclined to map a fault, from about a third of a mile N. of Pordey north-eastward, between Barraway and Haney Hill, and west of Delph Bridge. At Soham Causeway, Crooked Drain, Mk. Skertchly recorded the following section, also in 1874 :— Peat, 2 feet ; Sand (Lower Greensand), a foot; Kimeridge Clay. Several years later I learnt that a few coprolites had been worked, both on the northern and on the southern sides of the road at the western part of this outcrop. Outliers. The scattered phosphatic nodules that occur in the fields on the low ground, on either side of the high road, about a mile south-eastward of btuntney, seem hardly to justify the mapping of-Lower Greensand there Besides these there are also traces of saud, on the south-west ; so that probably the Lower Greensand must have come on there when the ground had been but little less lowered by erosion. At Lay Clerks Farm, south-eastward of Stuntney, there is a trace of sand, and Mr. Skertchly saw the phosphatic nodule-bed there. In a drain north-eastward of Norney, parallel with the wood I saw traces ol the nodules on Kimeridge Clay. Immediately east of the village of Stuntney the hill is capped by sand. A small patch has been mapped, by Mk. Skertchly, on the ton of Thorney Hill; v The only important outlier is at Ely, where the Lower Green- sand occurs over the high ground, toward Witchford and Thet- ford for a distance of about 1± miles from the cathedral and in the other direction (north-eastward) for probably a 'shorter distance, the northern boundary being hidden by the Boulder- Clay that comes on about half a mile from the cathedral LOWER CffiEENSAND. 29 Mr. Skertchly seems to have thought that the sand might extend a good way further, beneath the Boulder Clay, than has been shown on the map. The eastern end of this mass is in the Great Roslyn pit. Mr. Skertchly has left the following notes :— " A few phosphatic nodules occur, scattered over the surface of the land, on the eastern side of the road to Cambridge, where the boundary-line crosses the road, S.S.W. of My." " Further north, by the 66th milestone, there was a small pit (in 1874) in fine sand, red at top, but yellowish at about a foot down." " The pond at the angle of the fence (marked on the map) about a third of a mile west of the 66th milestone is at the junction with the Kimeridge Clay, and light-brown phosphatic nodules occur in the clay turned out; but they probably come from the base of the sand." " Three quarters of a mile a little S. of "W. from the cathedral, there have been extensive pits, but they were disused and overgrown in 1874. Fragments of a hard rock, two feet thick, were still to be seen : it consists of sandstone, with a few small polished black and brown quartz pebbles, the middle part full of larger but like pebbles, and I was told that it had been found 4 feet thick. It is, however, very varying, for, on the same horizon, may be found loose sand with pebbles, the bed not having been consolidated." " The south-western part of the cemetery, N.E. of the city, has been dug out, in parts to the depth of 12 feet, when j Kimeridge Olay is touched. The Lower Greensand contains ferruginous sandstone, said to be 2 feet thick. What seems to be Boulder Clay (from the description given) comes on above." Of, this Ely outlier Ma. Teall says : — " On the south side of the road leading from Eoslyn Hill pit to the town, the following section may be seen " : — * Drift with flints, &c, 2 ft. . rr I" Decomposed sandstone, 1 ft. n *- ■, -, < Light brown sandstone, with small pebbles, 1J ft. Irreensand.J [ Reddisll sand . Kimeridge Clay. Fossils. Our knowledge of the Lower Greensand fossils of Upware being so greatly derived from Mr. W. Keeping's work, it will be well to quote therefrom (pp. 8, 9, 31, 16-20). Palaeontologists working at this bed must, of course, use Mr. Keeping's Essay. He says : — '"The fossils of the Upware and Brickhill Neo- comians are preserved, for the most part, in calcite, the mineral being, in some of the zoological groups distinctly crystalline ; some few organic structures have been replaced by limonite, and fossil wood occurs in the usual silicified condition. Of other fossils only the inside moulds and external casts are known, those being formed of ferruginous sandstone, limonite, and phosphate of hme." * The Potton and Wicken Phosphatic Deposits, p. 23. 8vo. Camb. (1875). 30 LOWEB GREENSAND. " It is of the first importance at once to divide the fossils of these rocks into two great groups. All those which are mineral- ised in phosphate of lime, together with many of those in limonite are ' derived ' fossils " (as distinguished from the indigenous or native species). " This separation of the fossils . . is, as a rule, . . easy . . for the derived fossils besides being characterised by the materials in which they are preserved, belong mostly to Jurassic species, and they occur usually as internal moulds which have been mutilated by attrition as they were rolled into pebbles during long years of wear and tear upon the ancient sea-beach." The phosphatic nodules have been " much tunnelled by numerous boring organisms. These stone-borers were for the most part sponges, worms, and bivalve shells," especially the last. " The derived fossils belong to various ages, ranging at least from the Neocomian to the Oxford clay inclusive." For an exhaustive account of them the reader is referred to Mr. Keeping's book. Turning to the Indigenous Fauna Mb. Keeping notes that there are 151 species. "The most striking features of the bed are the magnificent developments of the Lamp shells, or Brachiopoda, and its exceeding richness in large cup sponges, and massive and dendroid Polyzoa." The native vertebrates are not abundant, and there is a difference of opinion about many of these, which have been thought to be reallv derived fossils. J "Of the Cephalopoda we have but very scanty representatives " and "specimens are rare of all the species." ... " Of Gasteropoda there are 16 species," mostly undescribed. " Of Lamellibranchiata the Ostreidce are conspicuous, as presenting ihe most striking forms and being the most numerous in individuals ihe great resemblance of the Upware oysters to those of the Jurassic rocks is very remarkable. . . The special development of the Arcadffi . . is also noteworthy." Fossils of the Lower G-heensand of Upware. From Mr. W. Keeping's work, The Fossils . . of Upware, . . 1883 mSljTeM™™ theRemamS0f Re P tiles andof Fislf are thought to be Crocodilian teeth and fragments of bone. G-eosaums (Dacosaurus). Ichthyosaurus. Meptilia. Iguauodon. Plesiosaurus. Pliosaurus ? Pisces. Acrodus. Asteracanthus. Gyrodus. Hybodus (with Sphenonchus). Ischyodus Townsendi, £uolcl. Otodus or Oxyrhina (teeth and ver- tebras). Pycnodus Couloni, Ag. Sphffirodus neocomiensis, Ag. Strophodus. LOWER GEEENSAND. 31 Cephalopoda. Ammonites cornuelianus, D'Orb. Deshayesii, Leym. Anoyloceras Hillsii, Sow. Belemnices pistillif'ormis, Blainv. subfusiformis, D'Orb. upwarensis, Keeping. Gasteropoda. Cerithium marollinum, D'Orb. neocomiense, Forbes. Litorina cantabrigensis, Keeping. ~ upwarensis, Keeping. — — varioosa, Keeping. ;sp. Nennsea tumida, Keeping. sp. Patella. Pleurotomaria gigantea, Sow. Renevieri, Keeping. Scalaria Keepingi, Gardn. Tessarolax Gardneri, Keeping. Tridactylus Walkeri, Gardn. Trocbus, n. sp. Turbo Eeedi, Keeping. Lamellibranehiata. Area Carteroni, D'Orb. marullensis, D'Orb. Astarte subdentata, Morn. sp. and new sp. Avicula cornueliana, D'Orb. P Avicula, sp. Cardita rotundata, P. and B. Cardium cottaldinum, D'Orb. subhillanum, Leym. Cuculleea subnana, P. and B. sp. Oypricardia arcadiformis, Keeping. squamosa, Keeping. striata, Gein. Cyprina angulata, var. rostrata, Sow. obtusa, Keeping. Sedgwickii, Walker. Exogyra Couloni, D'Orb. tombeckiana, D'Orb. Gryphsea dilatata (?), Sow. (P derived) . Lima farringdonensis, Sharpe. longa, Bom. Lithodomus. Modiola obesa, Keeping. Modiola pedernalis, Bom. ? sp. Neithea atava, Bom. Morrisii, P. and B. ornitbopus, Keeping. Nuoula subtrigona, K. and D. Opis neocomiensis, D'Orb. Ostreafrons, Parle, var. macroptera, Sow. Walkeri, Keeping. Panoptea gurgitis, D'Orb. plicata, Sow. Pecten Dutemplii, D'Orb. orbicularis, Sow., var. magnus, Keeping. raulinianus, D'Orb. Pectunculus marollensis, Leym. obliquus, Keeping. sublasvis, Sow. Pbolas (Pistulana) constricta, Phil. Plicatula Carteroni, D'Orb. equicostata, Keeping. P Tbracia or Tellina. Trigonia upwarensis, Lye. Brachiopoda. Bhynchonella antidicbotoma, Buv. cantabrigensis, Dav. depressa, Sow. latissima, Sow. — : — upwarensis, Dav. Terebratella Davidsoni, Walker. Pittoni, Meyer, var. * Menardi, Lam. Terebratula capillata, D'Arch. — — Dallassii, Walker. depressa, Lam. , vars. cantabri- gensis, Walker, cyrta, Walker, and uniplicata, Walker. extensa, Meyer. Terebratula Lankesteri, Walker. Meyeri, Walker. microtrema, Walker. moutoniana, D'Arch. prselonga, Sow. Seeleyi, Walker. sella, var. upwarensis, Walker. Waldheimia celtica, Mor. (?). Juddi, Walker. pseudojurensis, Leym. tamarindus, Sow., var. magna, Walker. Wanklyni, Walker. Woodwardi, Walker. * Added from Davidson, Pal. Soc. 32 LOWER GEEENSAND. Polyzoa. Oeriopora (Echinocava) Mich. (Reptomulticava) Entalophora angusta, D'Or dendroidea, Keeping. ramosissima, D'Orb. Heteropora arbuscula, coalescens, Beuss major, Keeping. ramosa, Horn. Raulini, maniilla, b. ? Heteropora (Hulticrescis) Miche- lini, D'Orb: (?). sp. (Nodicresois)annnlata,lTee2)Mi^. (Reptonodicrescis). Melicertites upwarensis, Keeping. Radiopora bulboBa, D'Orb. var. Reptomultisparsa haimeana, De Loriol. Semimulticava (Radiopora) tuber- culata, D'Orb. Serpula [Vermilia] ampullacea, Sow. antiquata, Sow. articulata, *SW. gordialis, Goldf. [Vermilia] lophioda, Goldf. Serpula plexus, Sow. rustica, Sow. Yermicularia Phillipsii, Bom. polygonalis, Sow. Echinodermata. Cidaris, sp. (and thorny spine). Peltastes Wrightii, Desor. Pseudodiadema rotulare, Ag. Spongida. Elasmostoma subpeziza, D'Orb. ; (peziza, Goldf.) Paehytilodia. Raphidonema (Oatagma) cupulifor- mis, From. porcatum, Sharpe. maeropora, Sharpe (=Elasmo- stoma acutimargo, Keeping, not Bom.) Tremacystia (Verticellites) anasto- mans, Mant. annulata, Keeping. clavata, Keeping. Gault. (By A. J. Jukes-Browne.) The Gault is only exposed at the surface over small areas, separated by tracts of gravel • and alluvium. It is of course assumed to be continuous beneath these superficial deposits, but no line has been engraved on the map for its boundary beneath the Fens. The Gault enters the district represented on Sheet 51, N.W., to the south of Oottenham. It then passes beneath a broad tract of river -gravel, but is exposed on the eastern side of this in a long strip between Waterbeach and Causeway End Farm. Thence it passes under the Fen to the south of Upware, the small patch of Gault to the west of the Coral Rag tract near Upware being probably an outlier. The Gault reaches the surface again by Wicken and Sohara, forming the horseshoe-shaped ridge which surrounds the plain of Soham Mere ; but to the west and north of Soham it again sinks beneath the Fens. GAULT. 33 It presents its usual character of a stiff bluish-grey clay, suitable for brick-making. It contains scattered phosphatic nodules, which are most abundant near the base ; and its thick- ness at Soham is proved by borings to be about 90 feet (see p. HI). The sections in the small tract of- Gault north of Upware have been mentioned on pp. 23-25, 27. The Gault has been worked for brick-making, beneath the fen, less than a mile a little E. of S. from Wicken Church (W. W.). The only good exposure of Gault in this dictrict was at a brickyard a mile west of Wicken Church. This was visited in 1880 by Mr. H. B. Woodward, who took the following notes: — "The yard is on the border of the Alluvium ; the clay is pale bluish, of a lighter tint at top, and, according to the workmen, it is stronger (i.e., stiffer) the deeper they go, the thickness of clay before reaching ' rock ' being about 50 feet. Shells occurred in a vein at a depth of 8 or 10 feet." The Grault i3 worked beneath peat and alluvial silt (W. W.). There was a brickyard by Horsecrofts, and nearly a mile a little W. of S. from Soham Church, another about half a mile north-west of the Church, and another by Soham Causeway, half a mile north-east of Soham Cotes. The Gault was also seen in the railway-cutting bv the last place (W. W. See p. 101). On the western side of Soham Mere the Gault overlaps the Lower Greensand and rests directly on the Coral Rag, lapping over the northern point of the ridge and forming the low hill on which Fordey Farm stands. Mr. H. B. Woodward, who revised the mapping of this locality in 1881, made the following note: — "East of Fordey Farm, and close by the Alluvium, Gault is reached beneath peaty soil, and, according to the tenant, it had been proved to a depth of 20 or 30 feet hereabouts. On the higher ground above the farm stiff pale greenish clay was shown, for a foot or more, in ditches and drain-cuttings." Two outliers have been mapped. One is a thin patch between the Boulder Clay and the Lower Greensand at Haney Hill, Barraway. The other caps the hill from Haddenham bo Wilburton, and the following note has been left by Mr. Skertchly : — " In the fields about the sand-pit half a mile S.E. of Haddenham church (see p. 21) there is bluish clay, yielding Belenvnites minimus and phosphatic nodules, which is probably Gault in place." (W. W.) IT 63615. 34 CHAPTER IV. CHALK. The classification of the Chalk adopted by the Geological Survey has been noticed on p. 3, and that classification is based on the occurrence of certain hard beds at definite horizons by tracing the outcrop of which beds a threefold division has been made, whilst in this and neighbouring tracts the lowest division is again divisible. The following description, to the end of the Middle Chalk, has been written by Mr. A. Jukes- Browne. Lower Chalk. General Description. Three palseontological zones are recognisable in the Lower Chalk. It would, however, give a more accurate idea of the vertical succession if the Lower Chalk were described as con- sisting of two broad zonal divisions, bounded and limited by three well-marked lithological horizons. The district now treated of is a natural continuation of that described in the Memoir on the Neighbourhood of Cambridge (published in 1880), and the sub- divisions of the Lower Chalk recognised in that area are as follows : — Zone of r Belemnite Marls - about 4 Feet. Holaster < Chalk of Cherry Hinton - „ 80 „ subglohosus., L Totternhoe Stone - ,, 15 ,, Zone of f chalkMarl . . -to „ Ammonites < X"r rj „ i -i mwm. )_ Cambridge Greemand - „ 1 „ Total thickness - 170 „ The Cambridge Greensand forms the base of the Chalk Marl, and rests on an uneven and eroded surface of the Gault. It is a marl so full of dark green grains of glauconite as to be more of a sand than a marl, and in this matrix are embedded the phosphatic nodules or " coprolites " which are so well known commercially. For a full account of this bed the reader is referred to the Memoir on the Neighbourhood of Cambridge. The Chalk Marl is a firm greyish marly chalk, with enough clayey matter to form a tough rock, locally known as chinch. In the Cambridge Memoir this subdivision was classified as the zone of Rhynchonella Martini, but it has since been thought preferable to call it by the name of the prevalent Ammonite (A. varians), the range of which has proved to be more limited than was formerly supposed, and which is a common fossil of the Chalk Marl throughout its southerly range, whereas the LOWER CHALK. 35 Rhynchonella, though generally present, is not always to be found. The lower part of the Chalk Marl has a lumpy and somewhat nodular structure, the harder and tougher parts being sur- rounded by softer and looser marl. Grains of glauconite are visible in it for some height above the basement greensand : the large visible grains become fewer aud fewer, but minute grains, visible only under the microscope, extend throughout. Chemical analysis shows that the lower part contains from 70 to 78 per cent, of calcium carbonate, with from 12 to 20 per cent, of insoluble siliceous matter, and a variable proportion of soluble iron and alumina (doubtless constituents of the glau- conite-grains). The chief part of the siliceous matter probably exists in the form of clay, but the microscope shows that there is a small proportion of fine quartz-sand. The microscope reveals also that the calcareous matter consists partly of fine calcareous mud or powder, and partly of recognisable organic atoms, such as Foraminifera (entire and broken), with small fragments of broken shells, Echinoderms, &c. The proportion of calcareous matter increases upward, and near Burwell the upper part is a tough blocky kind of chalk, with probably not less than 80 per cent, of carbonate of lime. The Tottemhoe Stone has generally been described as a brownish-grey sandy chalk, but microscopical examination shows that the roughness and apparent sandyness is really due to the quantity of comminuted shell-fragments which it con- tains ; chemical analysis, too, shows that it is essentially calcare- ous, a sample of the Burwell stone, containing nearly 86 per cent, of calcium carbonate. Its basement-bed is a remarkable stratum, consisting of hard grey gritty stone, full of green-coated phosphatic nodules, which vary in size from that of a pea to that of a walnut or small potato; this layer is a foot thick at Burwell, and is locally known as " brassil." It is persistent through Cambridgeshire, and probably through Suffolk and Norfolk. The mass of the stone occurs in thick beds, and cuts as a freestone, having an even grain, except that it contains numerous small broken bits of brown phosphate and many fossils. The highest bed at Burwell is a compact brownish-grey stone, rather harder than the rest, and known locally as the " bond " course ; it is there about 3 feet thick, but appears to thin out northward. The stone is, in fact, very variable in thickness; at Burwell it is from 15 to 20 feet thick, but it thins northward till it is only 4 feet at Stoke Ferry, in Norfolk. The minute structure of a typical sample of the stone is described by Mb. W. Hill, as consisting of from 60 to 70 per cent, of shell-fragments, generally of very uniform size, as if sorted by current-action, many glauconite-grains, which are often large, and frequently in the shape of perfect casts of Foraminifera, with a small per-centage of fine quartz-sand. c 2 36 LOWER CHALK. The Totternhoe Stone generally passes up into a tough Grey Chalk, blocky, close-grained and destitute, of glauconite- grains. At Cherry Hinton (south of our district) there is from 25 to 30 feet of such chalk, but at that height it passes rapidly into a hard white chalk, which breaks with a smooth clean fracture ; this continues for about 20 feet, and passes up into softer and more marly chalk, which is whiter than that above the Totternhoe Stone. The total thickness near Cambridge is 80 feet, but it appears to decrease toward the north. The harder white chalk is found on microscopical examina- tion to contrast with that below in the absence of shell-frag- ments, and in the presence of a large number of the small spherical bodies which are regarded as the primordial or dis- united cells of Globigerina ; these are embedded in a fine white calcareous earth, and the rock is, in fact, a variety of foramini- feral ooze or chalk. The number of the spherical cells becomes much less in the higher beds. At West Row, near Mildenhall, this division exhibits very abnormal lithological characters, and includes a band of reddish- pink chalk. The Belemnite Marls consist of two layers of shaly marl, separated by a course of hard compact white chalk. The lower bed of marl is generally greenish-grey ; the upper marl is yellowish or buff; fossils are not common in either, but Be- lemnitella plena occurs ocasionally, Ostrea vesieularis and Rhynchonella plicatilis more frequently. The white chalk splits with a smooth even fracture, and its structure resembles that of the white chalk in the zone below, single foraminiferal cells being scattered abundantly through a fine amorphous matrix. Cambridge Greensand. The Cambridge nodule-bed, which forms the base of the Chalk Marl, enters Sheet 51, N.W., beneath the Fen to the south- west of Reach and passes thence in a north-easterly direction beneath Burwell Fen. The coprolites were formerly worked at several points between Reach and Soham, and some particulars of these have been given in the Memoir on the " Geology of the Neighbourhood of Cambridge." The nodule-bed emerges from the fen at a point about five furlongs south-east of Wicken Church, and the outcrop then runs north-westerly to the church and thence for half a mile, when it bends north-easterly toward Horsecrofts, and is finally lost in the fen eastward of Soham. Mr. H. B. Woodward found that the coprolites were being worked east of "Wicken Church in 1880, and they have also been worked to the east of Horsecrofts, where the top three beds, noted under Well-sections (p. Ill), were seen in the pits by Mr. Skektchly. The outcrop by the Cherry Tree, south-east of Soham, is a little doubt- ful, but Mr. Skebtchly has noted a well, a quarter of a mile eastward of LOWER CHALK. 37 the house, in which " coprolites " were found at, the depth of about 10 feet. Coprolites have been dug on the north-eastern side of Brook Street (Soham outlier) at a depth of 10 feet. The whole of the southern part of Soham in fact stands upon Chalk Marl, which, with its basement-bed, extends westward to within a furlong of the railway-station. East of Soham the outcrop is concealed by gravel, but in 1872 Ma. Skeetchly saw coprolites dug near Wedd's Farm, two miles north-east of Soham, below a few feet of gravelly soil aud disturbed marl. This point is therefore close to the outcrop, and is at the same time the most easterly place to which the coprolites have been followed. No evidence was obtained in the progress of the Survey with regard to the continuation of the bed to the north-east under the Fens ; there can be little doubt, however, that the Cambridge Greensand, the noduliferous base of the Chalk Marl, preserves the same character for some miles further to the north-east, possibly as far as the northern edge of Sheet 51 : but the pro- bability is that the phosphatic nodules gradually decrease in number, so that beyond a certain point the seam would never be worth working for commercial purposes. Iri the absence of evidence no line has been engraved on the map for the base of the Chalk Marl beneath the Fens, in Sheet 51, N.E., but as an aid to future exploration it may be stated that the outcrop of the coprolite-bed may be expected to run from near Wedds Farm in an easterly direction through Isle- ham Fen as far as the River Lark, and thence to the north-east through Mildenhall Fen and Lakenheath Town Moor. [If, how- ever, the occurrence near Wedds Farm is part of the Soham outlier, rather than of the main mass the line may run from eastward of Soham, through the Fens in a north-easterly direc- tion, to the Lark. On the other hand the Soham mass may join on beneath the fen to the main mass. — W. W.] Chalk Marl and Totternhoe Stone. The sections in the large quarries of Burwell have been described in the Memoir on the Neighbourhood of Cambridge, but the railway from Cam- bridge to Mildenhall was not made when that memoir was written ; the following notes on the cuttings along this line have been placed at our disposal by Mk. W. Hiil, who examined it in 1886. " The entrance of the cutting immediately east of Burwell Station appeared to be in Chalk Marl, but the whole of it was faced and partly overgrown, and the only evidence obtainable was from the floor and from the heaps of debris at the base of the telegraph-posts, which presumably came from the holes dug for their erection'; in these Ammonites variaus, fragments of Twrilites (costatus?), and Ostrea vesicularis were abundant. A hundred yards further east Totternhoe Stone comes in and Rhynchonella mcmtelliana occurs in some quantity, with a few specimens of Am. varians and Ostrea. The eastern end of the cutting appears to be in Chalk Marl, but no fossils were found." 3S LOWER CHALK. The cuttings along the Soham and Newmarket line, from near Soham to Landwade, were thought to be in Chalk Marl by Mr. Whitaker, and the outcrop of the Totternhoe Stone along this line was not ascertained. From Me. Hills's notes, above quoted, it would appear ihat the Totternhoe Stone comes in with a synclinal, forming the ridge east of Burwell, and it thus appears probable that the low ground or Landwade valley coin- cides with an anticlinal flexure having a general north and south direction and bringing up the Chalk Marl. The first point beyond Burwell where traces of the stone were observed was in the shallow cutting on the railway to Mildenhall, seven furlongs north of Fordham Station, where a plot of ground, between the road and the line, has been levelled, and shallow trenches have been dug to facilitate the escape of the water. From these excavations fragments of hard rocky material have been turned out, which resemble the " brassil " or basement- bed of the Totternhoe Stone, containing green-coated nodules and a few fossils, such as Sliynclionella grasiana and Pecten fisicosta, P. quinque- costatus and Plicatula inflata, and many small fish-teeth. It seems to crop out here with an easterly dip. At Isleham there are two large quarries which have been worked for many years, and both expose sections of the Totternhoe Stone. That seen in the older quarry south of the church is as follows : — Feet. 4. Soil and rubble - - - - -2 to 3 3. Firm greyish-white chalk - - - 6 to 4 2. Hard grey chalk, rather rough and mottled with patches of darker grey, in thin beds 2 to 3 1. Grey stone in massive blocks - seen for 6 The beds numbered 2 are termed " the hards " by the workmen, and they occupy the place of the "bond course" at Burwell, but are litho- logically very different. The stone below is locally called " the blocks," and has the usual characters of Totternhoe Stone ; its base is not seen, but the men state that there is similar stone for another 6 feet, a different bed being then reached which they call " the greys." The other quarry is about a quarter of a mile east of the church and exposes a rather deeper section, but without showing the base of the stone. The stone is constantly burnt for lime, but is also used for rough build- ing and walling work when required. Mr. Whitaker notes that "it has been used in the construction of the church and in the old Priory barn, but not in the earliest work, which is of Barnack Stone. In modern times it has been used in the restoration of the church, some of the stone, however, having been brought from Burwell." [The following information was given me in 1884 by Mr. W. Marshall, of Ely. — W. W.]— " I never could find anybody who had sunk through the Chalk at Isleham, and the reason assigned was that so much water came in. We have now made a boring in one of the pits, where the saturation-level is 21 feet from the surface, and we have gone down 55 feet lower than that level, without going through to the Gault, a greater depth than I expected. The lowest part of the boring showed the bottom chalk to be much fissured ; so that the chisel went down 3 feet at a jump, shortly before the workmen gave over. I think that a very few feet more would have brought us to the Gault." (See account of well-section, p. 110.) When examining the cuttings on the Cambridge and Mildenhall line in 1886, Mr. W. Hill found traces of the Totternhoe Stone in the cutting which commences 400 yards west of Isleham Station. He says : — " The entrance of the cutting is, I believe, in Chalk Marl, but about 50 yards from the end the Totternhoe Stone comes in, and the blocks of chalk seen in the middle of the cutting have a reddish-brown tint on the outside, the colour penetrating about half an inch into the block ; the ' bond ' rock in some of the pits at Burwell is stained in a similar way, so that LOWEK CHALK. 39 the tap of. the Totternhoe Stone may here be indicated. JZhynchonella mantelliana and Ammonites varians occur throughout the cutting, but most plentifully near the entrance. The dip appears to be steady to the eastward, and between the station and Beck Bridge (Freckenham) the cutting appears to be in the grey chalk whioh overlies the stone. " When driving through this district with Mr. Hill in 1886 we did not find any exposure of Totternhoe Stone near West Row, but a quarry more than three quarters of a mile northward of the ferry showed hard grey gritty stone in thin beds, which weathers into rubbly lumps ; this is probably not far above the stone. The clunch-pit, marked on the map, nearly a mile and a quarter north- ward of the ferry, is now disused and turned into a garden, but we found a small exposure of brownish-grey gritty stone, like Totternhoe Stone, an identification which was afterwards confirmed by microscopical exami- nation. The slight feature made by the outcrop of the stone here can be followed as far as Beck Row, striking nearly N.N.E., but beyond that place the feature is obscured by the blown sand which overspreads so large a part of this district. Zones of Holaster subglobosus and of Belemnitella plena, The railway-cuttings west of Landwade are in grey chalk, but are now grassed over. Me. Whitakbe took- the following notes of the cutting south-west of Snailwell: — "At the south-eastern end there is brown loam, which includes a seam of blaokish earth and a whitish (calcareous) layer, and contains land and fresh-water shells : the upper part is stony (chiefly bits of chalk). This hardly reaches 30 yards, when white chalk rises up. Soon a pale greenish grey chalk comes on above the white, and then sinks to the bottom of the cutting, the level of which rises ; this bed is hard, partly nodular, with the prismatic or so-called ' striated' structure, and it includes a marly layer. Further on there is a buff sandy layer (? washed in by infiltration from the surface) in this bed, which seems to run through the cutting, but it is whiter and more rubbly at the north- ern end. Above it there is hard rubbly chalk." The greenish grey chalk and marly band is probably the zone of Belemnitella plena, and the rubbly chalk would be the base of the Melbouwi Eock. The engineer (Mr. Smith) informed Mr. Whitaker that a large Ammonite, 2 feet in diameter, was found in this cutting, and that boulders were found in the chalk. There is a small pit north-east of Fordham which appears to be in the grey chalk just above the Totternhoe Stone, but no fossils were found, and the chalk is in a peculiar broken and lumpy condition. Part of the railway-cutting near Isleham Station is in grey chalk, from which there seems to be a gradual passage downward into Totternhoe Stone. Crossing the River Lark the first and most important section is that in the large quarry, nearly half a mile north-east of West Bow Ferry. The remarkable bed of red chalk here exposed was described for the first time in 1887,* for so out of the way was this district before the railway to Mildenhall was constructed, that when Mb. W. Hill and the writer visited the quarry in 1886, one of the workmen said that we were the first strangers he had seen there, though he had worked in the quarry for 13 years. The band of red marly chalk is seen near the entrance to the pit, dipping westward at a low angle, but soon becoming horizontal and running along the whole face of the quarry till it is cut off by a fault, which brings up lower beds on the southern side. The complete, section * Geol. Mag., dec. iii„ vol. v., pp. 24-28. 40 LOWER CHALK. at the deepest part of the pit, not far from the entrance, was as f0ll0WB : - Feet. Soil and rubble of yellowish chalk - - - -4 Pink marly chalk, becoming yellow above - 3 Hard nodular grey chalk - - £5 Grey shaly chalk - - - - . " ." Very hard grey nodular chalk (Ammonites Austem, Belemm- tella plena, a.n& Terebratula semiglobosa) - - - 1 Thin-bedded whitish chalk - - - - * |z Hard greyish chalk - - - - r Softer thin-bedded chalk (Holaster subglohosus) - - - 6 Hard lumpy yellowish rocky layer - - - 0$ Softer chalk below, according to the workmen. At the western end of the quarry the red band lies at a greater depth, and its full thickness is seen to be about four feet, the following succession being here visible in 1886, along a face running east and west. Feet. Chalky soil - - - - - - - 1 Bough yellowish chalk, much weathered and broken - - 4 Bed chalk, soft and marly, brick-red at top weathering pink, lighter below - - - ... 4 Greyish white chalk, marly and platy, with hard lenticular lumps ------ -I2 Hard grey rocky chalk weathering into a rough nodular Burface - - ... - 2 Soft grey marly chalk, seen for ... - 14 The hard grey rock near the base of this section is certainly the same bed which directly underlies the red chalk in the eastern part of the pit, and the overlying white chalk is either a separate local bed, coming in west- ward, or it is a part of the band which is coloured pink to the eastward ; it is similar in appearance to the pink chalk above it, and, as this has lumps which are whitish outside, the colouring stain may not have extended down so far at this point. The western face (running nearly north and south) shows a fault, the succession, above described being cut off abruptly against soft whitish chalk in thin beds, of which neither top nor bottom are seen, but which are probably thrown up, as the fault-plane hades northward, and they may be part of the six feet of thin-bedded chalk in the lowest part of the deepest excavation. The hard beds on the northern side of the fault curve up slightly toward the fault-plane. The reddish-pink chalk breaks into small angular blocks, the edges of which are pinkish-white, and all the joint-planes which cross the bed are bordered by whitish bands about a third of an inch thick ; facts which seem to indicate that the percolation of water from the surface has effected a certain amount of decoloration, and that the whole was originally of uniform colour. The tint is darkest at the top, and becomes lighter toward the base. There is a further change of colour near the outcrop, where the whole bed weathers into yellow rubble. As the Local dip of the beds here is westerly, there must be an anticlinal to the east of the pit, and a second outcrop, with an easterly dip, nearer to Mildenhall, but of this no traces were seen. From the red band we did not obtain any fossils, but in the lower beds many have been found, Holaster subglohosus being fairly common and going far to establish the stratigraphical position of the beds in the face of their abnormal lithological characters. The occurrence of typical Belemnitella plena is particularly noteworthy, as such specimens have never yet been found at so low an horizon in the Chalk : the Belemnites referred to this species from the Totternhoe Stone of Burwell being really the B. lanceolata of Sowerby, and probably a distinct species. LOWER CHALK. 41 Elsewhere B. plena has only been found in white chalk at the very top of the Holaster subglobosus zone, and in the marls which overlie this. The chalk-pit a mile and a quarter north-east of Mildenhall, shows hard white blocky chalk similar to the higher part of that of Cherry Hinton, and there is no trace of anything like the peculiar beds of West Row. To the northward the country slopes gradually toward the fen, and the surface is occupied by blown sand. Fossils. Specimens of most of the fossils' named below are to be found in the Woodwardian Museum, Cambridge, or at Jermyn Street ; but a few were got only by Mil. Hill and myself. In this list, I = Isleham, W = West Eow. Totlernhoe Stone. Grey Chalk. Echinodermata. Discoidea cylindrica, Lam. Holaster subglobosus, Leslie — trecensis, Beym. Crustacea, Sfc. Enoploclytia brevimana, McCoy Grlyphaaa cretacea, McCoy Pollicipes glaber, Horn. Scalpellum maximum, Sow. Vermicularia umbonata, Sow. - Brachiopoda. Kingena lima, Befr. Rhynchonella Cuvieri, D'Orb. - mantelliana, Sow. plicatilis, Sow. Terebratula biplicata, Sow. semiglobosa, Sow. squamosa, Mont. - sulcifera, Mor. Terebratulina gracilis, Schloth. Inoceramus latus, Mant.( Lima globosa, Sow. Neithea quinquecostata, Sow. Ostrea vesicularis, Lam. Pecten elongatus ? Lam. orbicularis, Sow. Plicatula inflata, Sow. - Teredo amphisbsena, Goldf: LameUibrancMata. ■ orbicularis, Mimst.) Gasteropoda. Fusus, sp. Pleurotomaria, sp. Turboidea nodosa ? Seeley W W W W I. W w w w w w w 42 LOWER CHALK. Totternhoe Stone. Grey Chalk. Cephalopoda. Ammonites Austeni, Sharpe rothomagenais, D'Orb. varians, Sow. Baculites, ap. Belemnitella plena, Blainv. Nautilus deslongchampsianus, D'Orb. elegans, Sow. Turrilites costatus ? Lam. Pisces. Cimolichthys lewesiensis, Ag. Lamna (Otodus) appendiculata, Ag. Oxyrhina Mantelli, Ag. I. W I W The only fossils noted from the Chalk Marl are Ostrea vesicularis (from Burwell), Ammonites varians, and Turrilites costatus. Middle Chalk. General Description. The district treated of in this memoir being contiguous to that described in the " Geology of the Neighbourhood of Cam- bridge," the zonal succession of the Middle and Upper Chalk is doubtless the same as in that area. This district had, however, been surveyed before that memoir was published, and before the importance of the Melbourn Rock and, to some extent, of the Chalk Rock as divisional lines had been recognised. The general course of the Melbourn Eock has since been traced through Suffolk and Norfolk,* but that of the Chalk Rock or of the zone into which it expands is not yet known. The following table shows the succession which may be ex- pected to exist in the eastern portion of Sheet 51 : — Upper J Chalk with flints and Micrasters - ? 200 Feet. Chalk. \ Nodular rooky beds (Chalk Rock) - 20 iZone of Holaster planus - - 50 Zone of Terehratulina gracilis - 100 Zone of Rhynchonella Cuvieri - 40 Melbourn Rock ... 8 The Melbourn Eock, which forms the basement-bed of the Middle Chalk, is always conspicuous in those quarries where its base is exposed, because it rests directly on a soft buff marl (zone of Belemnitella plena), and as this crumbles, on exposure to the weather, the hard rock above forms a projecting and over- hanging cornice. The lower part of the rock is a hard nodular mass 3 or 4 feet thick, consisting of compact white chalk in irregular lumps or * By Messes. W. Hill, Jokes-Browne, and Whimker, see Quart. Journ. Geol. Soc, vol. rliii,, pp. 540, 503-571. (1887.) MIDDLE CHALK. 43 nodules which are embedded in a softer greenish-grey material, the whole forming a bed, or two massive beds, often much jointed. The upper part splits into thinner beds, the nodules occurring principally in layers from 6 to 18 inches apart, the chalk between these layers being compact and yellowish, with only ' a few small scattered nodules. There are occasionally partings of marl between the rocky beds, and these also contain nodules, on some of which young oysters may be found.* The Melbourn Kock passes upward into chalk which is hard, yellowish, and rocky, but less nodular than that below, and very full of fragments of Jnoceramus ; it is also more fossilif erous, Mhynchonella Guvieri and Jnoceramus mytiloides occurring in abundance. Higher up the rock becomes whiter, smoother and softer, the nodules disappearing about 20 feet above the rock. The topmost beds of this zone are massive, tough and creamy white, sometimes rather hard, as on the Gog Magog Hills. The first flints come in about 40 or 50 feet above the base of the rock, but are only scattered single flints, generally with very thin rinds or white skins, and always showing distinct traces of sponge-structure. The succeeding chalk (Zone of Terebratulina gracilis) is soft and white, in thick beds, with layers of soft grey marl at intervals. Flints are sometimes very numerous, and occur in layers of long finger-shaped nodules; but other parts of the zone are nearly destitute of flints. Echinoconus subrotundus is common in the lower part, Terebratulina gracilis and Ino- ceramus Brongniarti throughout the zone. The chalk itself is a nearly pure foraminiferal earth, microscopical examination showing that it consists of a fine calcareous powder embedding Foraniinifera of several kinds, entire and broken, the most abundant being Globigerina. [Of the Chalk Rock, the peculiar hard bed that divides the Middle from the Upper Chalk, no section has been seen in the district, and but one section hence northward through Norfolk. — W. W.] Melbourn Mock and Zone of Bhynchonella Guvieri. The outcrop of the Melbourn Kock has not yet been traced through the district, but its general course is known. It enters to the north-west of Newmarket, and passes to the south of the spring-head at Exning. The importance of this horizon was not known when this district was surveyed, and if any pits exist in it no notes were taken of the sections exposed. When the Bury and Soham Railway was being made, in 1879, Me. Whitak.ee recognised the Melbourn Kock and the underlying bands of shaly marl (zone of Belemnitella plena), in the cutting south-west of Snail- well, and his notes on this have been given on p. 39. The springs at Snailwell, and in Chippenham Park, are probably thrown out in the Melbourn Eock, but this is merely a surmise. * For a fuller and general description, see Quart. Journ. Geol. Soc, vol. xlii., pp. 218, 230. (1886.) 44 MIDDLE CHALK. North of the Kennett the country is covered with blown sand, but near Worlington Heath Farm there is a shallow pit which exposes the upper bed of the Melbourn Rock and some of the overlying nodular and shelly chalk; the section seen by myself and Mr. W. Hill in 1886* was as follows : — Feet. Gravelly soil and rubble - - - -4 Hard nodular whitish rock in thin beds, full of Inoceramus mytiloides and Rhynchonella Cuvieri - 4 Thin seam of greenish-grey marl. Hard nodular rocky chalk, white, with greenish marl between the lumps (no fossils) - - - 3 Talus hiding rock - - 4 The beds appear to have a slight dip east. The chalk terrace in which this pit is dug can be traced northward toward Worlington, and seems to emerge suddenly from beneath the great spread of grave] which covers the country between Freckenham and Worlington. It is very probable* indeed, that this gravel is banked up against the ridge formed by the outcrop of the Melbourn Rock. The rock is seen again in the cutting on the railway to Mildenhall, just south of Worlington House, and it appears to have been quarried formerly by the side of the main road north-east of that house. On the northern side of the Lark we could find no trace of its actual outcrop, but the town of Mildenhall stands on the hard shelly yellowish chalk of the Rhynchonella Guvieri zone ; chalk' of this description and containing that fossil, together with Echinoconus subrotundus and Inoceramus mytiloides, being exposed in a small pit at the eastern end of the town. The Melbourn Rock cannot therefore be far below the level of this pit. All the quarries on the slope which borders the eastern side of Eriswell Fen are above the horizon of the rock, and it seems probable that tha outcrop of the rock itself occurs near or a little below the level of the Fen, a position which it appears to hold as far as Lakenheath. An old pit by the side of the road five furlongs south-east of Eriswell church shows shelly chalk with many fragments of Inoceramus mytiloides. About a mile to the north of Eriswell there is a small pit in hard chalk containing the same shell and Rhynchonella Cuvieri. This is at a low level and probably not far above the rock. Between this and Lakenheath the country is deeply covered with blown sand. At Lakenheath, north-east of the church, there is a large quarry exposing about 30 feet of hard lumpy or nodular chalk that evidently belongs to this zone. The rock breaks principally along the joint-planes, and the weathered faces have a rubbly appearance, with large lumps of harder chalk standing out here and there, but not forming any definite or continuous bed. Fossils were unusually rare, Echinoconus subrotundus being the only one that was at all common. At the lowest level, near the entrance, harder and more regularly bedded rock is exposed, nodular and full of Inoceramus mytiloides, like that which always overlies the Melbourn Rock. Water comes in, according to the workmen, a few feet below the floor of this pit. Fossils. L. = Lakenheath. M. = Mildenhall. W. = Worlington. Echinoconus subrotundus, Mant., L. M. Rhynchonella Cuvieri, B'Orb., L. M. W. Terebratula semiglobosa, Sow., L. M. W. Inoceramus mytiloides, Mant., L. M. W. Ammonites peramplus, Mant., L. ? A. J. J-B. * See Quart. Journ. Geol. Soc, vol. xliii., p. 564. The remainder of the account of this zone is also taken from this paper. upper chalk. 45 Upper Chalk. As the older Tertiary beds do not come on above the Chalk for many miles eastward of our district, we may infer that the higher part of the Upper Chalk is not present, but has been eroded away. How much, however, of this division is present we do not know, its base not having been traced, from the absence of sections of the Chalk Rock, and from the eastern part of the tract being much hidden by Drift. The Upper Chalk is marked lithologically by the general occurrence of layers of flint-nodules, and sometimes of con- tinuous beds of flint ; but in parts flints are comparatively rare. North of the Lark the Chalk has been worked in various places for the sake of the flints, which were used for the making of gun-flints, an industry that still lingers at Brandon, just across our northern boundary. The following account of these pits is taken from a Memoir by Mr. Skertchly,* with some small additions and corrections from his note-book. Various local names are used. The following information about Icklingham was given by Mr. Ashley, who worked the pits for flints there. The stone used at Icklingham was dug on Icklingham Heath, close to the Seven Trees, 1J miles north of the village. The place is called Seven Trees Brek ;f the first part of the term applies to a clump of elms, of which five only remain, and the latter is synonymous with Field, an open space. The pits were very numerous, perhaps 500 in number, but their area is circumscribed. None were open at the time of my visit, and the only noticeable feature was the close proximity of the shafts, which averaged about 9 yards from one to another. The section at this place was, in 1876 :— Ft. In. Sand - - - lft. 6 in. to 3 Dead lime Soft white Chalk Toppings Flint - Soft Chalk First Pipe-clay 6 3 5 in. to 1 - 3 - 1 in. to 4 Hard Chalk, in large blocks, rings and smokes under the strokes of the pick - - - -20 Upper Crust Flints, large, scattered, mostly grey 6 in. to 1 6 Soft white Chalk - .-30 Second Pipe-clay - - - - - - lj White Chalk, rather hard - - - - 3 Wall Stone - - - - 1 ft. to 1 6 Soft Chalk, full of horns - --30 Hard Chalk ..... 3 ft. to 5 Third Pipe-clay - - - - - -01 Hard Chalk - - - - 1 ft. 6 in. to 2 Floor-stone - - - - 3 in. to 1 Moderately hard Chalk - - - -2 ft. to 3 Very hard Chalk - - - - - 8 ft. to 9 Bough and smooth Hack Flint, a regular layer, in this differing from, the stone at Lingheath. Only occasionally worked, and burrowed from above like wall-stone - - - - - 3 in. to 1 Mean about 45 * Memoirs of the Geological Survey. England and Wales. On the Manufacture of Gun-flints, the Methods of Excavating for Flint, the Age of Palaeolithic Man, and the Connexion between Neolithic Art and the Gun-flint Trade, pp. 10-14. (1879.) f Mr. Bennett says that Brek is a name given to the large fields. UPPER CHALK." The similarity of this section with those at Lingheath and Broomhill, from which it is distant 8 and 10 miles respectively, is very striking. A remarkable pit was sunk about 300 yards west of the above, in which the first three "stones" were missing. The section was as follows, according to Mr. Ashley : — Ft. In Sand - 3 Dead lime - 6 Soft white Chalk - 7 First Pipe-clay 3 Soft white Chalk - - 6 Second Pipe-clay - 1 Soft white Chalk - - about 12 Third Pipe-clay - - 1 Hard Ghalh - - 2 Oulls (Paramoudra), nearly 3 ft. in height, grey and grisly, and of no use for gun-flints, in three tiers with 3 in. partings of chalh between ' - - 9 Floor-stone in a regular sase [local name for layer]. The thicknesses of the chalk beds in the above section must be much overstated, for Mr. Ashley told me the pit was 25 ft. deep, whereas his account makes it 40. It is certain, however, that the pipe-clays were found as stated, and the local absence of the toppings, upper-crusts, and wall-stone, and the presence of gulls above the floor-stone are very singular. The stone obtained from Seven Trees Brek is very good, and of much better average quality than that found near Brandon. It is generally intensely black, often jackdaw-coloured, of good running quality, and the coats are hard. To save expense of cartage Ashley often quartered and flaked his stone on the spot, and the numerous cores lying about show how profligate he was of his wealth of stone, for very many of them would be gladly flaked over again by the Brandon men. Good stone is obtained from a chalk pit close to the lodge of Elvedon Park. The section was as follows in 1875 : — Feet. Sand (? wash) - - - - to 3 White Chalk, with scattered horns flints - - - 11 Pipe-clay (marl) ... - -a [In note-book, White Chalk, 3 ft., is inserted here.] Upper Crust Flints, large and irregular - - § White Chalk - - - - - 4} Wall stone (flints) - - - - • 1 White Chalk - - - 4 The upper crusts here yield the good flint. This is unusual, but some- times occurs at Lingheath ; the stone is known as " best upper-crust." The chalk lies regularly, and its beds average about a foot in., thickness. The layer of pipe-clay shows a north-easterly dip of 1°. A specimen of Ananchytes ovatus' was found here. At Shaker's Lodge, on Wangford Rabbit Warren, about 2£ miles south of Lingheath, on the summit of the hill, floor-stone was met with in sinking a well, and a trial-pit was opened ; the bed, however, has not been worked. The section was still open in 1875, and showed : — Feet. Sand, full of angular flints 1 to 3 Dead lime - I to 3 Sard Chalk 3 to 1 Floor-stone i UPPER CHALK. 47 This section affords a means of calculating the dip of the beds. The surface of the ground is 163 feet above Ordnance Datum, the floor-stone 158 feet. The surface at the Poor's Plantation, Lingheath, is about 50 feet above datum, the floor-stone 16 feet. The distance being 2J miles gives as the dip 143 feet in that distance, or 57 "2 feet a mile, equal to 1 in 93 or about half a degree. Old flint-pits are seen in and around Elms Plantation, in Brandon Park, about a mile due north of Shaker's Lodge, but I have not been able to obtain any account of the section. They were worked out before the Lingheath pits were started, and may perhaps have been dug before the gun-flint trade arose. Mr. 0. B. Kose has remarked that " at Thetford, cylindrical forms of flint from 18 to 24 inches in length are numerously distributed through the chalk ; they are very sonorous, clinking loudly when struck against each other . . Exceedingly thin seams of flint are seen " also.* The following notes, referring to the south-eastern corner of the district, are from Mr. J. H. Blake : — "At!a large chalk-pit on the western side of the road, a little more than half a mile S.W. by S. of Fornham All Saints Church, about 20 feet of chalk was exposed, containing flints irregularly interspersed. About 12 feet above the bottom of the pit, two tabular bands of flint, each from J to 1 inch thick, 6 inches apart and parallel, occurred in horizontal but slightly undulating planes, extending across the whole of the section. A little brown loamy clay overlaid the chalk." " Chalk is exposed in places in the neighbourhood of Fornham St. Martin Church, and also in the railway-cutting three eighths of a mile E.S.E." Other sections of Chalk will be noticed under Drift. * Proc. Geol. Assoc, vol. i., no. 8, p. 231. (1862.') 48 CHAPTER V. GLACIAL DRIFT. Oq leaving the Chalk we come to a great gap in the geological series, for in this district not only are the highest beds of the Chalk absent, but also the whole of the older Tertiary beds, and, moreover, no trace of the newer Tertiary beds (of Crag age) has yet been found, nor is such trace likely to occur. We find the Chalk, as well as the underlying formations, irregularly covered by the Glacial Drift. This Drift here consists chiefly of a great sheet and of isolated masses, of various sizes, of Boulder Clay ; bub beneath this clay there is in places gravel or sand, and less often loam ; these underlying beds being sometimes associated with a lower and thinner bed of Boulder Clay : again above the clay there are here and there patches of gravel, which are more easily classified with the Glacial Drift than otherwise. For the loam or brick-earth beneath the Boulder day Mr. Skertchly proposed the name Brandon Beds ;* but as this loam is endowed with older names, being probably the equivalent of part of the Lower Glacial, or of the Contorted Drift of Mr. S. V. Wood, as it does not occur at Brandon itself (though there are patches in the surrounding country), and as it is better developed in various other neighbourhoods, the name^ is hardly needed. Indeed it seems a questionable thing to give names to divisions of the Glacial Drift, other than such litho- logical ones as are needful, and the term Glacial Loam is quite -enough, for present purposes at all events. Beds Below the Boulder Clay. Although on the map loam has been shown distinct from gravel or sand, yet as the outcrops of these lower beds are small, when compared with the tract covered by Boulder Clay, and as, moreover, they occur somewhat irregularly, it will be convenient here to group the whole. Practically the distinction between loam and-gravel is important, but geologically, in this case, it is not so, as all these beds are closely allied, and of no great thickness. South of the Lark. In the western part of our district there are no beds which we can with certainty assign to this part of the Drift ; but possibly the small patch shown on the map more than a mile S.S.E. from Barraway may be so classed provisionally. Of this Mb. Skertchly noted, in 1874, that " there is sandy gravel at the northern end of Padney highland. The sand is like that of the Lower * Gun Flint Memoir, and Rep. Brit. Assoc, for 1879, Sections, p. 379. GLACIAL DRIFT. 49 Crreensand, with small angular flints, not bedded : it was seen to a depth of four feet, beneath a foot of moory soil." _Mr. Bennett notes the section shown in Pig. 3, as occurring "in a pit by the road half a mile south of Barton Mill," where, however, the lower beds do not come to the surface : — Fig. 3. Section in a Pit south of Barton Mill. Scale about 8 feet to an inch. iMt^Jh ! a. Reconstructed chalk, with pebbles of quartzite [ r part of Boulder Clay] . Dr'ft J *' ^ me buff laminated loam, passing into a. I c. Pebbly gravel, mostly of chalk, but with quartz and quartzite. I d. Sine false-bedded sand. e. Chalk. Fig. 4. Section in a Pit south of Tuddenham. V r j^emm OB ~~ < <^ ■' " * '' V T 'v '* * ' ' ■'i'" r L ^^3P ^T 11 3.B7.A a. Sand anrl gravel. Glacial Drift /* &* 1 - Boulder Clay. \ c. Loam. Vertical and Horizontal Scale the same. Height 30 feet (?Iess. — W. W.). Mr. Skertchly has left the following note of a, pit near Tuddenham. " Near the road about 1J miles south of the village was a section showing how Boulder Clay has worked up the loam, contorting it, dragging it from its original position, and so influencing it that in places it is difficult to know whether to call the material ' Boulder Clay made up of loam,' or ' loam mixed up with Boulder Clay.' On the right (east) of the section (Fig. 4) the Boulder Clay has squeezed under and tilted up a mass of the loam. In the centre the loam is not only tilted up but bent over, and a tongue of the B ou lder Clay (a few inches thick and several feet long) is injected in to the loam. At b 1 a mass of Boulder Clay lies distinct from the rest, as if it had been squeezed into that above." When I saw this old pit not much could be made out of it : one could see little but a confused jumble of loam and Boulder Clay ; but Mr. Bennett had also noted patches of loam in the Boulder Clay, the latter in one case penetrating some way into one of the masses. Mr. Bennett has recorded sections from Tuddenham to Hengrave, and the following descriptions are from his notes. TJ 63615. n 50 GLACIAL DRIFT. " In a stack-yard about half a mile south-east of Tuddenham Church the following beds were shown by a pit, to the depth of about six feet " :— Brown loam, sandy at top, bedded with bands of grey and puce ; from a foot to 6 feet or more, resting irregularly on the next and at one part going down below the bottom of the pit. On one side of the pipe thus formed there is a lining of gravel and buff sand, with a' carbonaceous band ; at the lower part of the other side a few land- shells (p) were found. Buff and grey loam, with a little chalk. " The upper bed may be merely the top weathered part of the lower one." "There is a patch of loam at Lackford Green, but nothing was seen to show its age." " A pit a quarter of a mile S.W. of Lackford Church gave the following section ": — "Brown Boulder Clay, with much chalk and some red chalk, and with a lenticular mass of chalk-rubble, up to a foot thick ; DrifV 2 feet. Sandy gravel ; 4 inches. Reconstructed chalk ; 2 feet. Chalk; 4 feet. "The patch of gravel mapped here, and that to the east, seem by position, to crop out from beneath the Boulder Clay, as these occur in small valleys, cut out of the Boulder Clay; but there is no direct evidence. Near the southern end of the western outcrop sand was seen, and- in the' other end the gravel and sand seemed to rest on the Chalk ; the gravel is largely made up of quartzite pebbles." " At a brick-kiln a mile south of Lackford Church there was at the top some 5 feet of Boulder Clay, with sand-galls, large unworn flints, and lenticular patches of clean clay, beneath which came brown sandy loam, said to be 9 feet thick and to be underlain by Chalk." " About a quarter of a mile south-westward of Flempton Church a pit, marked on the map, showed rather fine subangular gravel resting on Chalk and surrounded by Boulder Clay. The section was not clear, but the gravel, which is on high ground, seems to rise as a boss from beneath the clay." In the larger outcrop westward of Hengrave '" there was a kiln, a mile south of Mempton Church, but no good section was seen. Most of the earth is got from the Boulder Clay, which is washed and seems to contain some loam. At the edge of the wood brown clay, over 2 feet thick, was seen overlying rather coarse white sand, reddish at the base, to 4 feet. The well continues the section to the Chalk (see p. 114). Westward of Stanchels Farm Chalk has been dug ; but in this valley no pits were seen in the gravel, which has been mapped as Glacial from its position with regard to the surrounding Boulder Clay." The following is from Mr. J. H. Blake's notes : — " In a pit three eighths of a mile W.S.W. of Fornham All Saints Church layers or masses of coarse gravel and fine buff sand with small pebbles were seen, at the eastern side, in a nearly vertical position and abutting against Boulder Clay ; and other parts of the pit gave evidence of considerable disturbance subsequent to the deposition of all these beds. Many boulders of Lias shale and many coprolites, Belemnites, Grypheas, and other fossils were seen in the gravel." " In another pit, in a large field about five eighths of a mile south of the church, there was Boulder Clay at top, about 7 feet down in which a layer of coarse consolidated reddish-brown sand, with many shell-frag- ments, was seen. Underlying, and in some places tonguing into, the clay was a thickness of 6 feet of fine buff and sometimes false-bedded sand, and gravel, in layers and lenticular patches. Many angular and rounded boulders, up to 1$ feet in length and of various rocks, occurred in the' GLACIAL DKIl'T. 51 gravel as well as in the clay, together with quartz pebbles and angular flints, as well as various derived fossils." Between the Lark and the Little Ouse. To continue with Mb. Blake's notes : — "A pit in the southern part of the wood at St. John's Hill, and little more than half a mile S.S.E. of Fornham St. Genevieve Church, showed a thickness of about 4 feet of flint-gravel over sand, mostly buff, but reddish in places, and here and there with a few small flints, of which about 7 feet was seen." Me. Bennett notes that " a small pit about a mile a little S. of E. from Timworth Church showed Boulder Clay over buff sand. The gravel of Ampton Park and of Livermere Park is mapped as Glacial from its position, though there is no section showing the superposition of the Boulder Clay." The following account of the section at the brickyard about three quarters of a mile N.W. of Culford Hall is by Mb. Skeetchxy : — Fig. 5. Part of the Section at Culford Brickyard. Vertical and Horizontal Scales the same. S.BJ.S a. Boulder Clay. b. Hardened loam. c. Buff loam. " A very succession " clean section has been opened, showing the following. Feet. Oto 9 0tol2 15 15 Sand and gravel ..... ["Boulder Clay I Buff laminated loam Glacial Drift <( Harder loam, with seams of sand and oar- | bonaceous markings ... [_Cemented gravel, thin. Chalk. " The loams which dip south-west at a slight angle have been planed off by the Boulder Clay and in places are finely contorted. At first sight it would seem that the clay rested evenly on the loam ; but close inspection shows the above-mentioned points, and gives proof of the influence of pressure, for the top part of the loam has been converted into a hard mass, the laminae of which are parallel to the Boulder Clay above and not to the loam beneath." " The base of the Boulder Clay varies in character with the underlying loam : where the latter is more sandy, so also is the former." In a later note Mb. Skebtchly says : — "I have since found freshwater- shells, fragments of wood, and a worked flake here." The Rev. 0. Fishee has shown me a cast of the flake in question (I believe that I have seen the original also), and there can be no doubt as to its genuine character : it is said to have come from the brickearth. He also tells me that at a later date (about 1884) " the Boulder Clay at the eastern face of the pit was nearly worked away and had degenerated into a sandy gravel ; but on the southern side there was a fine exposure of it."* * See Fisiiek, Proc. Camb. Phil. Soc, vol. iii., p. 285, and Hughes, Journ. Anthrop. Inst., vol. vii., p. 162. D 2 52 GLACIAL DRIFT. When I saw the section there was a hollow of sand between the Boulder Olay and the loam, on the southern side. Eeturning to Me. Bennett's notes, " a small old pit half a mile north of "West Stow Church showed the following succession " : — Brown stony Boulder Olay, with chalk pebbles. At one part all the chalk has been dissolved out, and there are sand- galls : the division between this and the chalky clay was sharply marked and nearly vertical ; 6J feet. Thin layer of chocolate-coloured clean clay. Pinkish-brown clayey sand, weathering greenish, and having a marked even junction with the clay above ; li feet. Finely laminated brown sandy loam ; 6 inches. In the isolated patch of loam " about three quarters of a mile N.N.W. of West Stow Church, an old pit in a field, showed a capping of stiff reddish clay with a few flints, which may be weathered Boulder Clay, over very finely laminated buff loam." Our former colleague, Mk. A. Oolvin, found the impression of a small leaf in the loam here, on a visit with other geologists. " From south of Wordwell there is gravel up the valley eastward for more than 2 miles, with an outcrop of chalk in the valley-bottom for some way. At the southern, side of Limekiln Plantation, S.F. of Wordwell, a large pit showed a thickness of 18 feet of pebbly gravel, obscurely bedded, with a little sand in places, and at one place a thin layer of loam : many of the flint pebbles are large; but hard chalk pebbles, some of con- siderable size, form quite half of the material, and there is a fair quantity of red chalk pebbles. About a mile to the east, at the end of a cart-road, was another pit in coarse flint-gravel." " At the head of this outcrop, on the eastern side of the high road near the 5 mile-stone, is a large pit, about 25 feet deep, which showed alternating gravel and sand, capped at one place by a patch of Boulder Olay." To Mk. Skehtchly we owe the accompanying figure of a section near Livermere Heath Farm. He notes that '' in most places the Boulder Clay rests pretty evenly on the loam. Here and there, however, the former has worked into the latter, and, on the northern side, a tongue of the clay intruded into the loam." Fig. 6. sais. Vertical and Horizontal Scales the same. Depth 16 feet. a. Sand. Giacialf b. Boulder Clay. Drift \ c. Loam, dirty, with flints aDd pieces of chalk. A note by Mk. Bennett of a pit about a quarter of a mile 2ST.E. of the farm may refer to the same section. He adds quartzite pebbles and included pieces of Boulder Clay to the contents of the loam, and describes GLACIAL DRIFT. 53 it as rising up to the surface, though over too small an area to be mappable. Mn. Bennett continues : — On the western side of the high road, at the northern end of the gravel-patch, N.W. of the farm,, "a pit gave the following section, to a total depth of about 8 feet " : — Gravel, resting very irregularly on the next; from 10 to 2| feet. Fine gravel, of flints in a chalky matrix, resting very irregularly on, but passing down into, the next ; up to 5 feet. Reconstructed chalk, with unworn flints ; 1^ to 5 feet. Chalk seems to be touched at the base. From Wordwell along the edge of the great sheet of Boulder Clay, westward to above the Icklinghams, and then northward to near Downham High Lodge, no outcrop of beds between the Chalk and the Boulder Clay has been seen, and only one note of a section in such has been made. This section is near our northern boundary, and Mr. SftERTCHLYthus describes it. "A pit in May Day Plantation, by the eastern end of Brandon Park, gave a peculiar section, to a depth of about 16 feet, but unfortunately much hidden, in 1875. This seemed to show that the red sandy beds are of Glacial age, for light yellow Boulder Clay, full of striated pieces of chalk, was seen to overlie them here and there. At one part the gravelly sand was cemented, by carbonate of lime, into a conglomerate. Pinkish brickearth, with a tendency to lamination, was seen at one spot, overlain by Boulder Clay. Quartzite pebbles and small boulders occur sparingly in the Boulder Clay, but chalk is very abundant : blocks of septaria and of clay-ironstone lie about, and two large boulders of Neocomian Rand- stone, one with black phosphatic nodules." Prom a rough diagram of the ' apparent section ' in Mk. Skebtchltt 's note-book, it would seem that a little brickearth may occur above a little Boulder Clay, beneath which there is again brickearth, underlain by more Boulder I lay, thinning out sometimes, so that the sand and gravel at the bottom then underlies the brickearth. Prom this one may infer that we have here local beds, beneath the great sheet of Boulder Clay ; but it does not follow that other patches of sand and gravel, which occur only above Boulder Clay, in the neighbourhood are also of Glacial age. From the northern edge of the district, at Downham High Lodge, south-eastward to Thetford Heath, and then round by Elvedon and Calthorpe Heath, to Barnham St. Gregory, at the eastern edge, there are in places signs of beds of Glacial Drift below the Boulder Clay, though the outcrops are few and small. Speaking of the loam generally, Mr. Skertchly says — " I have noticed that in places, as near klvedon. where the loam is sandy and has Boulder Clay beneath, it seems little affected, whereas, where the loam is clayey, as at Thetford, it is much crumpled by the Boulder Clay beneath, as in other places, where it is overlain by Boulder Clay." " It would seem as if the tenacity of the clay enabled it to receive and retain contortion more readily than is the case with sand. Moreover, clay yields more to pressure than sand does." This is on the supposition that the Boulder Clay beneath the loam has been intruded, and was not pre-existent ; but this may be doubted, as a rule at all events. 54 GLACIAL DRIFT. The accompanying figure and description of the interesting section on the southern side of the road at Elvedon Gap* are by Mk. Skertohly, who saw the pit in good order. Pig. 7. Section at Elvedon Gap Brickyard. (Taken through the ceDtre of the pit.) £.b.j.i Feet. u,. Sand and gravel - - - - - - -3 ~b. Dark blue, tough boulder clay, full of scratched stones 6 c. Grey clay - - • - - - 4 d. Blue clay - - - - - .12 e. Rock. Consolidated loam, coherent enough to form a roof, beneath which the loam is tunnelled for a short Glacial j distance - - - - to 2 ■i Drift. ) f. Buff laminated loam - g. Loam (as above) and gravel - - h. Loam (as above) - i. Chalky clay, not seen, but described as like the top bed of Boulder Clay ..... j. Gravel, not seen (reached by boring) ... " The section, Fig. 7, shows the appearance of the pit, all the details being occasionally visible at once. The beds lie in a pot-hole, which has most likely been formed by the gradual solution of the chalk beneath. It is clear that the beds have not lost their relative positions, and the effect of the gradual sinking is shown by the occurrence of many tiny faults in the loam." " A well, 20 yards from the pit, passes through 2 feet of sand into the Chalk." At a later date the general seetion (as far as could be seen) seemed to be Boulder Clay over- laminated' loam &c, over sand, the beds being troughed, as shown above. At the northern end of the patch of loam a pit showed, at a later date, buff sandy laminated loam, resting in a hollow in light-coloured Boulder Clay. Me. Skertchly says that "near Elvedon buff loams and fine sands crop out beneath the Boulder Clay, 6 feet of which are also seen below." Mb. Bennett notes that about a mile south-westward of Elvedon, " by the 75th mile-stone, on the high road, a pit showed 20 feet of buff laminated sandy loam, capped by sand and resting in a hollow of Boulder Clay." It would seem, therefore, as if some of these beds are beneath the great sheet of Boulder Clay, but are accompanied by another bed of like clay. * On the old Ordnance Map there are two places of this name, and both on the same road ! One is 1£ miles N.E. of the village, and the other 2} miles S.W. of the same. The former is here meant. GLACIAL DRIFT. 55 Me. Bennett also notes " a large pit nearly half a mile S.E. of Barnham St. Gregory Church., showing brown sandy loam, with a black layer, which seems to rest on and pass into stiff brown and grey clay, boneath which, in the middle of the section, is brown bedded sand, with ferruginous bands, getting clayey at the bottom, rising in a boss. A clean cut at the western end showed dark slate-coloured clay, almost black at the lowest part, and with land-shells : bones also are said to have been found. Boulder Clay surrounds the brickearth (of which a thickness of about 20 feet was seen), but no junction-section occurred ; so that it is doubtful whether the latter is above or below the former :" Of the patch westward of Barnham, Mb. Skeetchly has left the following note : — "In 1876, the pit westward of North Farm, Barnham St. Gregory, was open to the depth, of 20 feet, and gave the following section " : — Sandy gravel, a mere wash, cutting into the bed below. Fine laminated buff loam, apparently composed of clay chalk and sand, lying in a long sweeping curve. Here and there a small black flint and a few bits of race. "About five chains further west another pit showed the loam, overlain by Boulder, Clay, into which it seems to pass in places. The thickness of the clay did not exceed 3 feet." There are also some isolated gravelly patches on the Chalk here. One, of sand and gravel, is less than a mile S.E. of Elvedon. Another stretches northward from the high road at the 78th mile-stone, S."W. of Thetford, and its northern end is suggestive of an esker, a name applied to certain long mounds of gravel, &c. of which further evidence was got during the progress of the Geological Survey in Norfolk. A pit on the eastern side of the plantation here, and about a quarter of a mile from the road, showed a hollow of sandy earth in gravel, which latter was mostly coarse and ■partly chalky. In the south-western corner of another pit, near the road, the chalk came to the surface at one part, being capped by a little coarse gravel on the one side and cut into by bedded sandy chalky gravel on the other. Away from the mass of the Boulder Clay a small patch of loam occurs beneath Boulder Clay near Mildenhall, and is of especial interest from Mr. Skertchlt having recorded the finding of worked flints therein. He remarks, " I have got no imple- ments, but have taken several flakes, from the loam. Mr. S. G. Fenton, formerly of Mildenhall, obtained a goodly number of rudely fashioned tools, and favoured me with drawings of about a dozen." At a later date Mr. Skertchly got a small implement, said to have come from the loam. He describes the section as follows : — " At the Mildenhall brickyard, N.E. of the town, the pits, as is often the case, are dry in winter and filled up in summer ; so that it is only by watching the work at various times that the true relations of the beds can be made out. The accompanying figure (8) shows the restored section, which I have seen in its entirety. At present [this was written about 1877] the exposure is not good, but Boulder Clay can be seen lying on the brick-clay. Several of my colleagues have seen the section and consider it to be quite satisfactory."* On a visit with Mb. Skebtchlt, I saw an unmistakeable mass of Boulder Clay resting in a hollow of the brick-clay ; but on a later visit this had disappeared, showing how such sections may vary from time to time. * See H. B. Woodward, Proc. Norwich Geol. Soc, pt. 1, p. 33. (1878) ; and Proc. Geol. Assoc, vol. ix., no. 3, pp. 125, 126. (1885.) 56 GLACIAL DRIFT. Fig. 8. Section at MildenhaU Brickyard. (Western side.") Vertical and Horizontal Scales the same. a. Sandy soil. „,.,„.,, f 6. Boulder Clay. Glacial Drift j c> Grey laminated loam . d. Chalk. " On the eastern side of the yard the following section was noted in 1875." Bedded sand and gravel ; 7 feet. Light-bluish loam ; 12 feet. Chalk. " To the westward another pit showed 10 feet of Boulder Clay, which was much indebted to the loam for its construction, and it is difficult to avoid the conclusion that the ice ploughed out most of the loam, leaving but a few isolated patches." " In the well chalk was seen on one side, at about 9 feet deep, and sand on the other side, the junction being apparently almost vertical." Of the Glacial age of the loam just described there can hardly be any doubt ; but the age of that at the northern part of Warren Hill, nearly two miles E.N.E. of MildenhaU Church, is by no means so certain, and by taking its description here one must not be understood to assert its title to the teriri Glacial. Unfortunately it must be described somewhere, and whether here or later on, amongst the Post-Glacial deposits, must go against the feelings of one or other group of geologists ; the principle, "first come first served " leads one to take the matter up at the earliest chance. The following account of the section is by Me. Skertchly, who also remarks that " a very fine pointed oval flint implement was found, measuring 4 * 2^ x finches. It had weathered to a pale ochreous colour, but in places retained its original blackness, and it is by far the finest specimen that I obtained from these loams." Fig. 9. General Section at Warren Hill, east of MildenhaU. HirriivTittd ."icaU I 3* 'FeU a. Sand aDd sandy soil, which spreads over all, as usual in the district. 6. Boulder Clay. ("Fine sand and chalky gravel, up to 22 feet thick, gradually thinning away I westward, towards the Boulder Clay. Yields flint implements and mam- c. i malian bones. Brickeartb, reddish-brown [rusted] above, blue below, seldom over 4 feet. L Yields implements and mammalian bones (Cervus, Elephas). d. Chalk. " Warren Hill, about If miles eastward of MildenhaU, has been long known as a locality for flint implements, and has been described by GLACIAL DRIFT. 57 Psop. Prestwich, Dk. J. Evans and others.* These authors class the bnckearth as Post-Glacial, because of its resting on Boulder Clay. I find however, that Boulder Clay rests on the implement-bearing beds, as -well as underlies them, as shown in the restored section Fig. 8." " The actual sections along this line were so close that at no place was there an interval of more than a few yards." " At the point under where a is marked in the figure, a pit now open [? about 1876] shows the following section, quite clear" : — Sand, to 2 feet. Boulder Clay, 4 feet. Coarse chalky flint gravel, 6 feet. Mottled red and blue clay, in which I found several worked flints, 5 feet. Boulder Clay, seen to 2 feet. " The late Mr. S. V. Wood, Jun. ; on seeiDg a section across Warren Hill, that I had drawn, suggested that the loams may really be newer than the Boulder Clay. He remarked that these beds, being of freshwater origin, may have been deposited by streams that flowed between banks of Boulder Clay, and undercut those banks. I do not doubt that such cases may occur, though I never saw a stream undercut its bank yards inwards." North- of the Little Ouse. We have now to treat only of a very small tract north of Thetford, where, however, there are or have been, good sections. These have been recorded by Mr. Skertchly, and the following description is mostly by him, with some additions from Mr. Bennett's notes, and from my own. The introductory para- graph was clearly written on the supposition that the. Boulder Clay, seen is the same bed as the great mass to the south ; but this seems by no means certain, and when seeing the pit south of the Waterworks I was inclined to regard the Boulder Clay there rather as one of those lower beds that sometimes occur in such a position. " At Thetford the loam is not entirely buried in Glacial clay, and an explanation of the relation of the loam to the Boulder Clay, given on the spot by Mr. T. Belt, seems to meet the facts of the case better than any other ; namely, that the ice, moving along the valley of the Little Ouse, pushed its moraine beneath the loam at this point, but did not succeed in lifting it right away. We must, of course, suppose that the loam was buried beneath the Boulder Clay and then exposed by denudation." " A most instructive set of sections occurred around the Waterworks, which I was enabled to study under exceptionally favourable circum- stances, during the progress of the works (in 1877?). From the Water- works southward to the brickyard I saw a continuous section, given by the well and the excavations for cisterns, by the trenches in which the pipes were laid, by an old pit, and by the brickyard close by. Besides these I obtained details of all the pits and trial-holes that had been made by the brickmakers during the previous twenty years." " The accompanying general section (fig. 10) has been made with great care from levels taken by the theodolite, and from the information noted above." * Phil. Trans., vol. cliv., p. 253. (1864) ; Ancient Stone Implements of Great Britain, pp. 488-492. (1872.) 58 GLACIAL DRIFT. fr s o Si, 8 ^ •' <=^ « ^ GLACIAL DRLFT. 59 " The sand and gravel lies irregularly on the beds beneath. The Boulder Clay underlies the loam for a distance of 5 chains only, and is missing at the Waterworks and at the eastern side of the brickyard to the south. I believe this Boulder Clay to be a tongue intruded beneath the loam, and this opinion is supported by the disturbance which the latter has undergone, from the clay beneath. The presence of Boulder Clay under the loam does not, therefore, prove that the loam is newer than that clay." " The proof that Boulder Clay also overlies the loam was not patent ; but I have satisfied myself that such is the case. Trial-holes have been made over a considerable area, for the purpose of finding the loam, and in every instance this, as well as the underlying Boulder day, was found to thin out, as the Boulder Clay thickened upon it higher up the hill." There is no Boulder Clay on the hill-top, however, and no evidence that any occurs over the loam. In every section hereabouts the clay is beneath the loam. Of course if, as has been suggested above, the clay in question does not belong to the great sheet of Boulder Clay, but is a lower bed, it is possible., and indeed probable, that the clay of the great sheet is newer than the loam, and this conclusion led Mr. Bennett and myself, at a later time, to class the loam as Glacial, rather than as Post- Glacial. Some observers have preferred the latter classification, because of the occurrence of Boulder Clay beneath the loam ; but the conclusion is by no means warranted : it is not enough to find a Boulder Clay beneath some other bed to justify one in calling the latter Post-Glacial ; it is needful to find the Boulder Clay, that is clay which can be identified as belonging to the great sheet, for there are various beds of Boulder Clay. The details of the Thetford sections are as follows : — Brickyard nearly half a mile N.N.W. of the Railway Station. Sand and gravel ; up to 8 or 10 feet. CI c'al f Dark bluish-grey laminated clay ; up to 12'feet or more. p. -f, { Buff loam ; said to be up to 16 feet. UTin - [ Boulder Clay, to Chalk ; to 7 feet. Pit on the other side of the high road, a little South of the Waterworks. The letters correspond with those of Pig. 11, from a sketch made at a later date by Me. Bennett. a. Sand and gravel ; up to. 7 feet. fb. Buff laminated loam ; up to 7 feet. ri • , \c. Bluish-grey clay, laminated toward the base, and scem- TVW i in § t0 P a8S int0 the next • 3 t0 7 feet ' d. Buff laminated loam ; a foot or more. Le. Light-coloured Boulder Clay, to Chalk; up to 10 feet. /. Chalk [? regarded as a boulder by Ms. Skektchly], seen to 6 feet. The Drift beds have an easterly inclination, cutting into the Chalk in that direction. Fig. 11. Section in a Pit south of Thetford Waterworks. d_ c tj. f Buff loam; 6 to 7 feet. Glacial Drift | Blue Clay> to Chalk . ig feefc Old Pot Kiln, about half a mile N.E. Sand and gravel ; 6 feet. Red clay, to Chalk ; 10 to 20 feet. Mk. Bennett gives the following note of a pit two thirds of a mile N.E . of the Railway Station : — f Gravel and sand ; about 1J feet, p,, . , | Brown sandy laminated loam ; up to about 1£ feet. ,-. ■„. ■{ Blown chalky Boulder Clay, showing inclined bedding, and containing a lenticular mass of reconstructed chalk (with [_ Boulder Clay in its midst) ; 24 feet or more. Chalk, at one part. A smaller pit, dug below the bottom of the main one, gave a section showing alternating layers of broken up chalk and of Boulder Clay, as in Fig. 12, in 1881.— (W. W.) Fig. 12. Section in a Pit a mile N.N.E. of Thetford. 1. Buff sandy Boulder Claj'. 2. Broken up chalk and flints. 3. Chalk and flints. ? in place, or more of 2. This section is described here on the supposition that the Boulder Clay may be one of those lower beds that sometimes occur, rather than belonging to the great mass at a higher horizon. 61 CHAPTER VI. GLACIAL DRIFT. Boulder Clay. General Account. We have now to notice that division of the Glacial Drift which most clearly owes its formation to ice. It is a bluish grey clay, which changes, by weathering, to a pale grey or to a yellowish brown ; in some cases the weathering goes to the extent of the dissolving out of all the chalky matter, and then the characteristic feature of the deposit is lost. This clay is mostly crowded with stones of various sorts and sizes, by far the com- monest being chalk and flints, so much so indeed as to give a marked chalky character to the whole bed. Many of the stones, notably the fragments and boulders of hard chalk, show signs of the action of ice, their surfaces being smoothed and scratched in the same fashion as are stones from beneath existing glaciers. The stones from other formations point mostly to a northern origin, and show that the ice must have had therefore a general southerly movement, whether it was land-ice, or water-borne ice, or partly one and partly the other, a question of a highly controversial kind. Lest the name Boulder Clay may mislead, it may be well to note that the great majority of the stones are of no great size, ranging down to very small pebbles : large stones, however, are common ; but actual boulders are less so, and none of very great size have been noted in our district, except for the great erratic of Roswell (Ely) and perhaps for certain large masses of chalk near Thetford, which Mr. Skertchly takes to be huge included boulders. There are sometimes also patches of loam in the clay. In the western part of the district, that is in Ely and in the neighbouring islands, there are outlying patches of Boulder Clay, some of fair size. In the central part it is absent, except for some small patches, having been almost entirely eroJed away. The vast amount of erosion that has taken place in Post- Glacial times over this tract, from the Fens for miles eastward, is apparent, as one cannot doubt that the Boulder Clay once stretched right across the whole. On the east, however, we have broad spurs that join on to the great sheet of Boulder Clay east- ward and southward, and which are only separated from one another by the valley of the Lark and of its tributary from Ampton. The greatest thickness of the Boulder CJay in the district is uncertain, we have no record beyond 50 feet, at Ingham (see p. 114) ; but probably over great part of its area this clay is of less thickness than the figure given. 62 GLACIAL DRIFT. Mr. Skertchly has remarked, in speaking of the large flints found in the Boulder Clay at Elvedon Lodge (see p. 70) that " it is very significant of the local origin of that deposit, that the flints are not cracked or weathered, and are suitable for knap- ping [some of them have been worked for gun-flints]. Had these stones travelled far, or been much exposed, they must have become weathered and unfit for knapping ; but although striated they are as sound as ever, and the coats are not much reduced in thickness."* ■ Mr. Bennett notes that "in mapping the Boulder Clay from Bury St. Edmunds westward a change of character (from the normal condition on the east) became apparent. This was noticed in a privately printed postscript to a paper of 3 884,t the substance of which is now reproduced." " Further investigation has led me to change my view as to the reason for the difference in the Boulder Clay westward of Bury St. Edmunds, Thetford, &c. from that eastward of those places." " In the former tract the clay lessens much in thickness, with a maximum of 25 feet, occurs in patches, is brown, sandy and very chalky, and contains many unworn flints and boulders of local origin. Outside this tract we find an almost unbroken sheet of the well-known bluish-grey clay, reaching a thickness of 100 feet, made up chiefly of chalk and flints in a clay-matrix, and with the usual assemblage of foreign (or distantly derived) boulders. Thus one seems to contain mostly local rocks, whilst the other is largely made up of foreign rocks. Along the line between these two kinds of clay there are sections showing them apparently interbedded." " The conclusion I come to is that the two clays are the results of two glaciations. The thin sandy clay with local detritus seems to have come from the north-west, over a Neocomian and Chalk tract, and may have been formed by land-ice. The thick blue Boulder Clay, with foreign stones, may be due to a north- eastern glaciation. But the two were formed contemporaneously, as shown by the interbedding along the dividing line, which line was the meeting of the two glaciers." Local Details. From Sutton Boulder Olay stretches over the higher ground eastward to Witcham, and by Wentworth to Witchford. Ma. Srertchly says that " large masses of chalk are not peculiar to Boslyn Hole (to be described directly), for one occurs in the Boulder Clay in Witcham Fields, but it is of minor importance. At Little Hill, a mile N.W. of the last place, the Boulder Olay is light-brown and full of stones, chiefly chalk and flints. Hereabouts the Boulder Clay goes farther down the slope, towards West Fen, than it does nearer Ely." * Gun Flint Memoir, p. 14. 1879. t " On the Glacial Question and the Drifts of East Anglia," Proc. Norwich Geol. Soc, pt. viii., pp. 252-262. The postscript added to separate copies. 1886. GLACIAL DRIFT, 63 The next patch to the east is but just cut ofl' by the little valley a!6ng which runs Grnnty Fen Drain, and it caps most of the higher ground from the road between Witchford and Thebford northward to Ely. Me. Skertciily notes that " a similar old valley (to that of Roslyn Pit) filled with Boulder Clay is intersected by the highway about half way between "Witchford and Ely." Of the northern end. of this patch he remarks that " the Boulder Olay on the eastern side of the high road, just out of Ely on the south, where the Witchford road joins, contain inter- calated coarse gravel, merely a mass of veins in the Boulder Clay," but enough to be mapped as gravel. Northward from Ely is another mass, to Chetisham and nearly to Downham, which gives one of the finest sections that have ever been seen, in the great pit of Roslyn or Roswell Hill, north- eastward of the city. The following account of this important section (to p. 69) has been compiled from Mil. Skertchly's published description,* supplemented by his MS. notes, and with other additions. The attention of local geologists has long been drawn to Roslyn Hole from the fact that various newer rocks (Boulder Clay, Chalk Marl, and Gault) there abut against the Kimeridge CJay, in which alone the north-eastern face of the pit is cut. The Gault has not been found in place within nearly three miles, and the nearest Chalk Marl is five miles off; their occurrence here, therefore, is remarkable enough. The result of this remarkable assemblage of rocks in so abnormal a position is that the pits have a literature of their own, valuable not merely for the theoretical views brought forward, but also as preserving a record of the changing aspects of the section. Phot. Sedgwick published the first notice of Eoslyn Holes in 1846, t ascribing the presence of the Chalk to a fault with a downthrow of about 150 feet which "took place immediately before the deposit of the brown cla/y"' (Boulder Clay). This paper is illustrated with diagrams which show that the Kimeridge Clay now exposed upon the east of the pit was not then visible. Pkop. H. G. Seeley next described the section, in three papers, in 1864 and 1865,J but as he published a later article, in 1868, there is no need to refer to these, save as illustrating the history of the subject and to note that, in the first of them, he alludes to the view that the Chalk here is merely " a drifted mass, included in the Boulder clay ; " but only to condemn it, on the ground that from " a section showing Kimmeridge Clay and Chalk side by side, and Boulder clay between them .... the conclusion inevitably followed that there had been a great fault, letting down the Chalk for at least two or three hundred feet :" reasoning that seems somewhat difficult to follow. In 1867 the Rev. 0. Eisheb, for the first time publicly brought forward the boulder-theory, § urging that ' ' the mere size of the mass of cretaceous strata at Ely is no argument against its having been carried thither by ice," noting that " the chalk thins out to nothing, the boulder clay passing beneath it," and concluding that the evidence "is against the occurrence of a fault, and points to the boulder clay * The Geology of the i'enland, pp. 236-241. t Rep. Brit. Assoc, for 1845, Sections, p. 42. J Geol. Mag., vol. i., pp. 150-154, vol. ii., pp. 2fi2, 265, 529-534. ■ § Proc. Camh. Phil. Soc, vol. ii:, pt. iv., p. 51. Reprinted in Geol. Mag.,vo\. v., pp. 407-411. (1868) ; and note on p. 438. 64 GLACIAL DRIFT. occupying a trough, which it has ploughed out for itself in the old sea bottom of Kimmeridge clay." The next year Proe. Seeley * again took up his pen, in defence of the theory that he had supported, and treated Mr. Fisher's view to some pleasant banter. He appealed to the existence of slickensides as in his favour, and illustrated his views with two sections, the one showing the beds as he saw and interpreted them at the last, and the other, of a highly ideal character, giving a restored view of the Cretaceous beds overlying Kimeridge Olay horizontally (before their denudation), and then plunging down almost vertically into the earth. It was not until 1872, however, that the question of how the Cretaceous beds got here was set at rest, by Prof. BoNNEY.f who had visited the pit from time to time in the foregoing three years. He gave four diagram- matic sections across the pit, from north to south, two of which clearly show Boulder Clay going beneath Gault, and a map showing the position of the beds in the floor of the pit. After supposing every circumstance favourable to simplicity he showed that the fault-theory needed most involved phenomena, such as two reversed faults with an ordinary downthrow-fault outside each (all later than the Boulder Clay and near together), and- he said "I conclude, therefore, that this arrangement is so extraordinary that it renders the fault theory in the highest degree improbable. We are accordingly driven to consider this mass of Cretaceous rocks, as either slipped from above, or dropped as a boulder of gigantic size into a pre-existing valley. Though no doubt there have been slips from the cliffs on the south bank of this valley, I do not think that we can very well explain the position of this mass of Chalk ... on the first of these theories." It is then noted that such large boulders are not unprecedented. The further evidence to the same effect got during the progress of the Geological Survey was noted in a general memoir by Mr. Skertchly.J We may now describe the details of the section, as recorded by Mr. Skeetchly, to which description but slight addition can be made, the southern side of the pit being little touched of late ; and then wo may show the bearing of the observed facts on the question of the boulder. The great set of clay-pits known as Boslyn or Roswell Holes is about a mile E.N.E. of Ely Cathedral, beginning at the base of the narrow tongue of Lower Greensand and stretching in a south-easterly direction nearly from the top to the base of the slope of the Kimeridge Clay. The material is dug for the repair of the banks of the Bedford Level. The pits contain water to depths up to 25 feet, and the area is irregularly divided into four-sided portions, by banks left for the purpose, which can be examined from a boat, and were of great consequence in tracing the run of the beds, a work that needed some care, as the banks are now and then renewed with a capping of clay, which may be either KimGridge Clay, Gault, or Boulder Clay. A plan of the pits is given in Pig. 13, from a survey by myself. Chalk and Gault have been dropped into a narrow space, hollowed out of the Kimeridge Clay, and Boulder Clay was seen in place where marked. The western end of Roslyn Pit cutB the boundary-line of the Lower Greensand, which formation occurs, indeed, in place in the fields to the west. In following this boundary we come suddenly upon the mass of Boulder Olay in question ; and, if the section were not open, the contour of the ground would not lead to the discovery of the Drift beds. These beds, in fact, fill up a small valley which can be traced to the river on the east, and towards Little London on the west. The pits can be most conveniently described in portions, which may be called the Great, Middle, and Lower Pits. The Great Pit lies to the * Geol. Mag., vol. v., pp. 347-349. (1868.") f Geol. May., vol. ix., pp. 403-408. For the most part reprinted in his "Cambridgeshire Geology," pp. 69-76. 8vo. Cambridge, 1875. t The Geology of the Fenland, pp. 236-241. 1877. For the most part now reproduced (to p. 69). GLACIAL DEIFT. 65 1*; O 2 .M "3-3 WO no S55 S.-STSlSj,,, g S.Soa