fyxmll Hmwmtg |f itag BOUGHT WITH THE INCOME FROM THE SAGE ENDOWMENT FUND THE GIFT OF 3-lcin n m. Sag* 1891 fam&. flBm/a 3777 Cornell University Library QE 262.M5L23 1909 The geology of the Melton Mowbray distri 3 1924 004 553 552 MEMOIRS OF TIE GEOLOGICAL SURVEY. ENGLAND AND WALES. EXPLANATION OF SHEET 142. THE GEOLOGY OF THE MELTON MOWBRAY DISTKICT AND SOUTH-EAST NOTTINGHAM- SHIRE. BY G. W. LAMPLUGH, F.R.S. j W. GIBSON, D.Sc. ; C. B. WEDD, B.A.; R. L. SHERLOCK, B.Sa, and B. SMITH, M.A. With Notes by C. FOX-STRANGWAYS, F.G.S. LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE, BY DARLING & SON, Ltd., 34-40, BACON STREET, E. And to.be purchased from E; STANFORD, 12, 13, and 1$, Long Ace-g, London ; W. & A. K. JOHNSTON, Ltd., 2, St. Andukw Square, Edinbubgh; HODGES, FIGGIS & Oo^ Gbafton Stbeet, Dublin ; From any Agent for the sale of Ordnance Survey Maps ; or through any Bookseller, from T. Fisher Un win, 1, AdelphJS Terrace, London, W.C., who ia the Sole Wholesale Agent to the Trade outside the County of London. - HBFi 1909. Price Two Shillings and Threepence. GEOLOGICAL SURVEY AND MUSEUM. (Ofmce : 28, Jermtk Street, London, S.W.) PUBLICATIONS RELATING TO THE SIX-INCH SURVEY OP THE MIDLAND DISTRICT. MAPS. GENERAL MAP ON THE SCALE OF £ INCH^l MILE (1 to 253440). Sheet 11, which included large parts of Parbyshire, Nottinghamshire, Cheshire. Staffordshire, Leicestershire, Rutland and Lincolnshire is in course of preparation. ONE-INCH MAPS, NEW SERIES, ON THE SCALE OF 1 INCH=1 MILE (1 to 63360). Sheet 110 (Macclesfield, Crewe, &c.) 1906 ; Explanatory Memoir, price 2s, 6d. (1E06). Sheet 123 (Stoke- upon-Trent) 1906 ; Explanatory Memoir (2nd Edition), price Is. Gd. (1905). Sheet 125 (Derby and Wirksworth) 1907 ; Explanatory Memoir, price 3s. (1908). ■ - Sheet 126 (Nottingham and Newark) 19"Q8 ; .Explanatory Memoir, price 2s. 3d. (1908). ' Sheet 141 (Derby, Loughborough, &c.) 1905; .Explanatory Memoir, price 2s. (1905). Sheet 142 (Melton Mowbray) 1909 ; Explanatory Memoir. Sheet 155 (Atherstone) 1899 ; Explanatory MemoirTprice 2s. (1900). Sheet 156 (Leicester) 1903 ; Explanatory Memoir, price 3s. (19031. Colour-printed drift editions, price Is. Gd. each, of all the above one-inch maps, with, the exception df Sheet 155, a- e published. A colour-printed solid edition of Sheet 123, price Is. Gd., is also issued. Sheet 155 (Solid or Drift) and Sheet 156 (Solid) are obtainable at present in the hand-coloured form only. 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/cu31924004553552 fc< -a IS o a o O C5 C3 ™ a >5 s l-H m IK EO -3 J ta T3 o T) $■ a 85 CM o tel crt J C5 ►3 O * •a « Ed o EC a > a B « a o IS o A MEMOIRS OF THE GEOLOGICAL SUEVEY. ENGLAND AND WALES. EXPLANATION OF SHEET 142. THE GEOLOGY OF THE MELTON MOWBRAY DISTRICT AND SOUTH-EAST NOTTINGHAM- SHIRE. BY G. W. LAMPLUGH, F.R.S. ; W. GIBSON, D.Sc; C. B. WEDD, B.A.; R. L. SHERLOCK, B.Sc, and B. SMITH, M.A. With Notes bt C. FOX-STRANGWAYS, F.G.S. LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE, BY DARLING & SON, Ltd., 34-40, BACON STREET, E. And to be purchased from E. STANFORD, 12. 13, and 14, Long Acre, London ; W. & A. K. JOHNSTON, Ltd., 2, St. Andrew Square, Edinburgh ; HODGES, FIGGIS & Co., Grafton Street, Dublin; From an)' Agent for the sale of Ordnance Survey Maps ; or through any Bookseller, from T. Fisher TJnwin, 1, Adelphi Terrace, London, W.C., who is the Sole Wholesale Agent to the Trade outside the County of London. 1909. Price Two Shillings and Threepence. in PREFACE The original geological survey of the area was made on the Old Series one-inch map ; the north-western part, on Sheet 71 S.E. having been surveyed by Edward Hull ; the south-western part, on Sheet 63 N.E. by H. H. Howell ; the north-eastern part, on Sheet 70 by W. H. Holloway, A. J . Jukes-Browne and W. H. Dalton ; and the south-western part on Sheet 64 by J. W. Judd. The recent re-survey on the 6-inch scale, on which the new map is based, was begun by Mr. C. Fox-Strangways" before his retire- ment in 1904, and was completed in 1906 under the superintendence of Mr. G. W. Lamplugh, who has also acted as editor to the present Memoir. The names of the various officers engaged on the work and the areas for which they are severally responsible are recorded on page iv. The memoir describes the geology as depicted on Sheet 142 of the New Series Colour-printed One-inch Map. The map is pub- lished in a Drift edition only, but the continuation of the boundaries of the i Solid ' rocks, where concealed by Drift, is shown by engraved lines. The western half of the new one-inch map differs in some important particulars from the corresponding portions of the earlier maps on the same scale. The boulder-clay which attains a great thickness over an extensive tract of country in the area in question and the Rhsetic beds are now represented for the first time. The oldest rocks actually exposed at the surface belong tojhe Trias, but the presence of deep-seated Coal Measures has been ascertained by borings in the north-western part of the area, as described by Dr. Gibson in Chapter II. The commercial value of the extension of the Nottinghamshire Coal-field into the area represented by this sheet remains to be proved. At present the principal mineral products of economic consequence in the district are the iron-ores of the Middle Lias, the cement-stones of the Lower Lias, and the gypsum of the Keuper formation. The extensive workings for these njinerals are described in subsequent chapters. We have received much assistance from the firms engaged in all these industries and desire to express our appreciation of their courteous help. J. J. H. TEALL, Director. Geological Survey Office, 28, Jermyn Street, London, 17th August, 1909. (12262—17.) Wt. 28120 500. 10/09. D & S. IV LIST OF SIX-INCH MAPS. The following is a list of the six-inch Geological Maps included in the area, of which MS. coloured copies are deposited for public reference in the Library of the Geological Survey and Museum of Practical Geology : — Nottinghamshire. Quarter-Sheets. 46 NB., NW., SB., SW., by R. L. Sherlock. 47 NE., NW., SW., by B. Smith. 47 SE. (= Leicestershire 6 SE.), by B. Smith. 50 NB., NW., by R. L. Sherlock. 50 SE., SW. (= Leicestershire 11 SB-, SW.), by R. L. Sherlock. 51 NW., SW.(= Leicestershire 12 NW., SW.), by B. Smith. also small portions of — 42 SE., SW., by R. L. Sherlock. 43 SE., SW., by W. B. Wright. Leicestershire. 7 NE., NW., SE., SW., by W. Gibson. 12 NE., SE. (= Nottinghamshire 51 NE., SE.), by G. W. Lamplugh. 13 NE., NW., SE., SW., by C. B. Wedd. 18 NE., NW., SE., SW., by C. Fox-Strangways. 19 NE., NW., SE., SW., by C. Fox-Strangways. 20 NE., NW,, SE., SW., by C. B. Wedd. m CONTENTS Preface by the Director List of Six-inch Maps iv Chapter I. — General Description 1-8 Introduction, 1. Physical Features and Geological Structure, 1. Keuper Marl : Rhaetic Beds : Lower Lias : 3. Middle Lias, 4. Upper Lias : Lower Oolites : 5. Glacial, 6 ; and Post-Glacial Deposits, 7. Previous Literature, 7. Table of Formations, 8. Chapter II.— Concealed Carboniferous and Older RoCks ... 9-11 Borings, 9. Underground Structure, 10. Chapter III.— Trias 12-21 Keuper : General Account, 12. Details : — North-western Area, 13 ; South-western Area, 15 ; Tea-green Marl, 16. RHjETIC : General Account, 17. Details, 18. Chapter IV.— Lower Lias ... ... 22-39 General Account, 22. Details :— Hydraulic Limestones, 25 ; Clays below Ferruginous Limestone, 30 ; Ferruginous Limestone and overlying Clays, 32 ; Belt of Sandy Shale and Limestone, 33 ; Clays above Semicostatus Beds, 36. Chapter V. — Middle Lias ... 40-49 General Account, 40. Details : — Clays and lower part of Marl- stone, 41 ; Marlstone, with Ironstone, 44. Chapter VI. — Upper Lias 50-53 General Account, 50. Details, 51. Chapter VII.— Inferior Oolite 54-61 General Account, 54. Northampton Beds, 55 ; Details, 56. Lincolnshire Limestone, 59 ; Details, 60. Chapter VIII.— Glacial Deposits ... 62-86 General Account, 62. Details : — Melton Mowbray and neighbour- hood, 67 ; Boulder Clay of the plateau, 69 ; Wreak Valley, 74 ; Stanton Tunnel, 77 ; Distribution of Boulders, 79 ; West margin of plateau, 80 ; Vale of Belvoir, 83. Late Glacial : Older River Gravel and other flood-deposits, 84. Chapter IX. — Post-Glacial River Gravel and Alluvium ... 87-89 River Gravel, 87. Alluvium, 87. Details, 88. Chapter X. — Economic Geology 90-103 Coal, 90. Middle Lias Ironstones : General Account, 90 : Details of the workings, 93. Northampton Ironstone, 95. Gypsum, 96. Lime and Cement, 97. Water supply, 98. Agricultural Geology, 99. Appendix I. — Some Important Borings and Sinkings 104-107 Owthorpe, 104. Ruddington, 105. Holwell Iron Works, 106. Melton Mowbray, 106. Saxby, 107. Scalford, 107. Notes of other sections, 107. Appendix II. — List of some Works on the Geology of the District 108-109 Index 110-118 VI LIST OF ILLUSTRATIONS. Plates. Page. Plate I.— Ironstone Working £ mile WNW. of Wartnaby, showing Boulder Clay on Middle Eias Marlstone Front. „ II. — Quarry near Cream Lodge, 1 mile NE. of Barrow-upon-Soar, showing Contortion in Hydraulic Limestones of Lowe - Lias 30 „, III. — Section in the same Ironstone Working as Plate I, showing Boulder Clay, and Upper Lias filling a .fissure in Middle Lias Ironstone ... 70 ,, IV. — Hydraulic Limestone Quarry £ mile E. of Barrow-upon-Soar 97 Figures in Text. Fig. 1.— Sketch-map of the Area of Sheet 142 2 „ 2. — Section through the Bhaetic Escarpment at Blue Hill, .Nottingham and Grantham- Canal.- 19 „ 3. — Generalized Section across the Lower Lias of the Vale of-Belvoir 23 „ 4.— Diagrammatic Section of the Boulder Clay and Bhaetic Escarpments in valleys neat the north end of the Wolds ... 27 „ 5. — Section in the Inferior Oolites near Walthamon-the- Wolds .(from Mem.. Geol. Surv. ' Geology of the SW. part of Lincolnshire," etc.) 57 „ 6.— Section in the Ironstone Quarry at Stonepit Houses near Wartnaby (Plate I) showing "gull" filled with Boulder Clay and Upper Lias ... ,. 70 „ 7.— Section showing Glacial Sand in valley NE. of Eaton Churoh 73 „ 8.— Section through the Stanton Tunnel on the Midland Railway 78 „ 9. — Plan to show the variation of the Boulder Clay and the range of certain Boulders on the north part of the Wolds ... 79 „ 10.— Sketch-map to illustrate the outcrop of the Middle Lias Ironstones 93 THE GEOLOGY OF THE MELTON MOWBRAY DISTRICT AND SOUTH-EAST NOTTINGHAM- SHIRE. CHAPTER I. GENERAL DESCRIPTION. 1 Introduction. The area of the map (New Series, Sheet 142) described^ in this memoir is shown on a reduced scale in the index-map on the next page (Fig. 1), which will suffice to indicate its limits. In the Old Series maps of the one-inch scale on which the previous Survey- was carried out, the greater part of the area fell within the quarter- sheet 71 SE. (published in 1855, with additions in 1879), and smaller portions within the \ sheet 63 NE. (1855, additions 1873), and the whole sheets 64 (1872) and 70 (1886). For the two sheets last-mentioned there were separate 'drift' editions, in which the glacial deposits were shown ; but the old £ sheets 63 NE. and 71 SE. represented the ' solid ' geology only, there having been no mapping of the drifts in most of the area of the present sheet. The recent survey was carried out on field-maps of the six-inch to the mile scale, from which the reduction was made to the one-inch scale, now published. Copies of the original six-inch maps, of which a list is given on p. iv, are available for public reference at the Library of the Geological Survey and Museum, Jermyn Street, London. The field-work in the south-western part of the map, as far north as Stanford-upon-Soar and eastward to Kirby Bellars, was done by Mr. C. Fox-Strangways before 1901 ; the rest of the ground was surveyed by the other authors of this memoir in 1906. Physical Features and Geological Structure. The whole area of the map lies within the drainage basin of the Trent. This river just touches the extreme north-western corner of the tract, at Clifton; and its important tributary, the Soar, crosses the south-western comer between Barrow and Stanford. The Wreak, a feeder of the Soar, with its eastern prolongation, the Eye, drains most of the southern area before swinging across the 1 By G. W. Lamplugh. GENEltAL L)JSSUKl±"HUJ>i. southern margin at Brooksby. The other streams are of less importance, being the minor feeders of the Wreak and Soar in the south and south-west; Fairham Brook in the north-west; and the upper waters of the Smite and Devon in the north and north- east. Fig. l.—Area of Sheet 142 (Melton Mowbray). •Ives tone JBeLvoir^ tO MILES. J These small streams flow almost radially away from the plateau of boulder-clay in the south-western part of the map ; and from the prominent escarpment of Middle Lias Marlstone against which the drift is banked, in the eastern part. The relation of these streams to the drifts indicates that the subsidiary drainage system has been developed since the glaciation of the district. In aspect, the whole area is an undulating country of low relief, ranging from about 100 ft. above sea-level in the lowest valleys to over 500 ft. on the uplands ; the highest points being on the Middle Lias escarpment north of Ab Kettleby (560 ft. above O.D.), and on the Inferior Oolite at Waltham-on-the- Wolds (573 ft.). The dominant physical features are dependent upon the characters of the underlying rocks. It is the purpose of the following intro- ductory notice of the strata, in upward succession, to bring out this relationship. The general dip of the rocks is very gently toward the south- east or .hib-hi., so that the oldest strata crop out in the western part of the sheet and newer beds set in successively as we so eastward. J ° Keupek MARL-The red and greenish-grey marls of the Upper Keupe.r which occupy the north-western corneT of the area and extend all along its western margin, are the oSest strata AND GEOLOGICAL STRUCTURE. 3 exposed at the surface. They form undulating low ground, bounded on the east by the steep escarpment of the KhEetic and Lias ; and they also run for some distance up the deeper valleys by which this escarpment is notched. Only the upper part of the formation is represented in this map, the outcrop revealing not more than about 300 ft. of strata, while the full thickness as determined by borings (see p. 12) is at least 630 ft. The predominant deep red colour of the marls disappears near the top of the formation, the uppermost 20 ft. or so being of a pale greenish tint and of distinctive aspect, whence this portion of the series is known as the 'tea- green marl.' At a few feet below the base of the tea-green marl irregular deposits of gypsum frequently occur among the marls, though not so abundantly in this area as in the country immediately to the north and west, in Sheets 126 and 141. The Keuper Marl appears to have been deposited in an inland sea or salt lake, and there is evidence that arid desert conditions prevailed during the period on the surrounding lands. In this district, so far as is known, it is entirely unfossiliferous. Rh^btic Beds. — These beds were formerly included with the overlying Lias, but they are now regarded as the uppermost sub- division of the Trias, and are separately indicated on the map. They consist of black and grey shales with thin lenticular bands of limestone in the upper part, the whole series being about 30 ft. thick. Their outcrop forms a narrow belt along the upper slopes and crest of the low escarpment overlooking the Keuper flat. Where not obscured by glacial drift, this escarpment may be traced continuously from the eastern side of the Soar valley in the SW. corner of the map to the northern margin beyond Owthorpe, and the outcrop also loops back into the map in two valleys farther eastward, at Colston Basset and at Langar. The Rhsetic contains a limited set of fossils belonging to marine types, but apparently developed under peculiar and somewhat unfavourable conditions. It represents the transition from the inland sea of the Keuper to the open sea of the Lias. Lower Lias.— In superficial extent, the Lower Lias is the most important formation of the map, its outcrop occupying two- thirds of the total area, if we include the tracts in which it is covered by the glacial deposits. It consists principally of dark blue shales, weathering at the surface to stiff brown or grey clay, with which are intercalated occasional thin bands of hard limestone. These flaggy limestone-bands are most abundant at the base of the series, where they are extensively dug for making hydraulic cement. They also occur at more widely-spaced intervals through the greater part of the sequence, becoming, however, quite rare and incon- spicuous in the uppermost portion. They usually form slight ridges or 'features' along their outcrop, by which their course may be traced ; and it is to their presence that the above-mentioned sharp escarpment at the base of the formation is mainly due. As a whole, the Lower Lias, where not covered with Boulder Clay, has been denuded to a broad longitudinal valley, bordered on the one side by the dip-slope of the basal limestones, and on the other side by die steep edge of the Middle Lias Marlstone. An 4 GENERAL DESCRIPTION. ill-defined portion of this depression in the north-eastern part of the map is commonly known as the Vale of Belvoir, and as the application of the term appears to be vague, it may be conveniently used to cover the well-marked lowland of Lower Lias which extends south-westward until abruptly terminated by the plateau of Boulder Clay stretching from Owthorpe to Old Dalby. This plateau-drift covers nearly all the western and southern portions of the Lower Lias outcrop in the map, so that in these parts it is only in the deeper valleys that the formation is actually exposed at the surface, or is directly responsible for the shape of the ground. The total thickness of the Lower Lias is about 650 feet. Middle Lias. — The lower part of the Middle Lias consists of bluish clay or shale, somewhat sandy in places, but not differing much in composition from the Lower Lias, and practically indistinguishable from it except by means of its special fossils. Therefore this portion, which is estimated to be about 100 ft. in thickness, presents no individuality in the shaping of the ground, but simply forms a prolongation of the Lower Lias clayey country. It is otherwise with the upper part of the Middle Lias, known as the Marlstone, which is very distinct in its lithological characters, being a relatively' hard calcareous sandstone overlain by or passing up into a highly ferruginous rock which makes a valuable iron-ore. This indurated Marlstone has given rise to a bold escarpment — the most sharply defined feature within the map — rising abruptly for 200 to 300 ft. above the Vale of Belvoir and stretching unbrokenly for 12 miles, from Belvoir Castle to the neighbourhood of Old Dalby. In this escarpment the Marlstone division, which does not exceed 40 ft. in thickness, forms a protective capping to the under- lying clays that build up the greater part of the slope. For the most part, the ground rises well above the 500 ft. contour along the crest, attaining its maximum elevation of 560 ft. above O.D. at Broughton Hill near Ab Kettleby. The escarpment between Stathern and Belvoir Castle being well-timbered and charmingly picturesque is one of the celebrated view-points of the Midlands. The dip-slope of the Marlstone, where not obscured by drift, forms a plateau inclining gently south-eastward. The ironstone is exposed at the surface on this plateau and has already been removed by shallow workings over a considerable portion of the outcrop. In its northern part, between Belvoir and Eastwell, the plateau has been deeply dissected by the ramifying valleys at the head of the River Devon, which are cut down into the underlying clays ; and similar conditions recur farther southward, around Scalford and around Holwell, at the heads of small streams tributary to the River Wreak. Being a permeable rock, the Marlstone throws out numerous springs at its base, from which these streams are principally fed. West of Scalford, the Marlstone runs in a long tapering spur to Old Dalby, having the underlying clays to the south as well as to the north of it. This spur denotes a slight change in the direction of the dip, or possibly a very shallow synclinal structure. The termination of the spur and its southern edge are overlapped and obscured by the great sheet of Boulder Clay which covers the rest of the country in this direction. Considering the wide THYSICAL FEATURES AND GEOLOGICAL STRUCTURE. 5 extension of the Boulder Clay to the westward as well as to the southward, it is remarkable that such a large proportion of the Marlstone outcrop should be free from this covering. Upper Lias. — The dark clays of the Upper Lias, overlying the Marlstone, occupy a narrow belt which swings into the eastern part of our district in a short loop, entering on the north near Croxton Park, running thence to Scalford and back to the eastern margin south of Stonesby. The greater part of the outcrop is, however, hidden under Boulder Clay so that the actual boundaries are often uncertain. Where not thus hidden, as between Branston and Croxton Park, it forms a sloping tract of stiff clay-land, rising sharply to the escarpment of the Lower Oolites. The thickness of the Upper Lias is about 120 ft. Like the rest of the Lias in this district it is a purely marine deposit, though its lowest beds indicate, shallow water. Lower Oolites : Northampton Beds. — The tract lying within the above-described loop of Upper Lias in the eastern part of the map is occupied by the two local subdivisions of the Lower or Inferior Oolite known respectively as the Northampton Beds and the Lincolnshire' Limestone. The lower portion of the Northampton Beds (the " Northampton Sand ") consists of ferruginous sand-rock, passing in places into an ironstone which was formerly mined near Waltham. The thickness of the sand-rock is usually about 24 ft. Where not obscured by drift, as in the neighbourhood of Croxton Park, its outcrop is marked by a well-defined bank capping the slopes of Upper Lias clay, but the overlapping of the Boulder Clay and the faulting near Waltham destroy the continuity of this feature and cause difficulty in tracing the division in some places. Its fossils prove that the. sand is of marine origin. The upper part of the Northampton Beds (the " Lower Estuarine Series ") consists of a variable group of grey and blue laminated clays, and soft yellow sand, 15 to 20 ft. in thickness, which appears to be of estuarine origin. It is at present very sparingly exposed in the district and occupies a strip of featureless flat ground. Lincolnshire Limestone. — The uppermost of the 'solid' formations shown on the map is the Lincolnshire Limestone which covers a tract of about 2 sq. miles between Waltham and Croxton, and is faulted in again a little farther westward as a long narrow out- lier running north from Waltham. In composition it is a tolerably well-bedded cream-coloured limestone, more or less oolitic, con- taining many marine fossils. Only the lower part of the limestone, to a thickness not proved to exceed 26 ft., enters the map ; and instead of presenting the remarkably bold feature by which it is generally characterized in Lincolnshire, the edge of its outcrop has for the most part hardly any effect upon the surface-relief. Never- theless, the plateau wherein it is developed contains the highest ground within the map, reaching 573 ft. at Waltham and 571 ft. on the road NW. of Croxton Park. From the Keuper Marl up to the Lincolnshire Limestone, the formations represent a practically unbroken sequence of sediments, 6 GENERAL DESCRIPTION. lying evenly one above another, without conspicuous unconformity* and all affected equally by the very gentle tilting which has produced the prevalent south-easterly dip of the strata. The remainder of the Mesozoic formations and the entire Tertiaries are unrepresented in the district, pre-glacial denudation having swept away such later deposits as may once have existed. It was not until the Pleistocene glaciation of the country that any permanent addition was made to the stratigraphical sequence as we now find it. Glacial Deposits. — In the southern part of the map, the whole country up to the margin of the Soar valley is covered by a great sheet of Boulder Clay, so that, as already mentioned, it is only in the bottoms of the deeper valleys in this tract that the 'solid ' formations reach the surface. The matrix of this Boulder Clay has been derived principally from the Liassic and other argillaceous Mesozoic deposits, while the stones and boulders which are embedded in this matrix include abundant fragments of Chalk, Chalk-flints, Lincolnshire Limestone, Middle Lias Marlstone, Lower Lias limestones and many quartzite pebbles from the Bunter, together with less abundant blocks of sandstone and lime- stone from the Carboniferous formation and a few igneous rocks of still more distant origin. Many of the boulders are characteristic- ally striated ; and the whole evidence warrants the deduction that the Boulder Clay is the product of an ice-sheet which swept over the district. The Boulder Clay has levelled up all the minor inequalities of the pre-glacial surface, and its thickness is therefore very irregular, ranging up to at least 150 ft. in the old hollows. It appears originally to have formed a gently undulating plateau, rising to nearly 500 ft. above sea level between the valley of the Wreak and the Vale of Belvoir, but declining gradually northward. This plateau is, however, now much dissected by the steep little valleys that carry away its drainage on all sides, so that the boulder-clay country is for the most part sharply and irregularly undulating. The main plateau of Boulder Clay has a tapering prolongation northward which reaches just beyond the northern edge of the map. Upon the eastern side of this lobe there is usually a sudden fall of the ground for at least 100 ft., the slope consisting of Lower Lias capped by Boulder Clay. The driftless plain of the Vale of Belvoir extends up to the foot of this feature which appears to owe its origin to the Boulder Clay and to be, in fact, a boulder-clay escarpment. Along the western margin of the drift plateau the glacial deposits include numerous masses of stratified sand and gravel ; and similar masses occur also along the Wreak valley and in a few other places. They appear to be mostly the product of waters draining the edge of the ice-sheet at various stages of its advance and retreat. They are too limited in extent to have much influence upon the topography, though occasionally in the Keuper area of the north-western part of the map they cap small isolated hills perhaps due to their protection ; and in a few other places particu- larly at the head of the Devon south of Belvoir, they form narrow high-lying terraces within the valleys. PREVIOUS LITERATURE. 7 FoST-GrLAClAL Deposits. — Since the deposition of the Boulder Clay the erosion of the district has been very con- siderable, so that there are wide-spread river deposits in the larger valleys. Thus, the valleys of the Soar and Wreak are flanked by broad terraces of flood-gravel lying 20 to 30 ft. above the present alluvial flat. The older of these terraces probably date back to the close of the Glacial period, as the remains of extinct mammalia, including the mammoth, have been found in them. Since that time the streams have diminished greatly in volume and have formed their lower flats of silt and loam. On the soft clays of the Lias even these lower alluvial flats are disproportionately wide in relation to the meagre streams with which they are associated. The flat ground likewise frequently extends on both sides beyond the actual limits of the stream-deposits, probably owing to the rapid weather- ing down of the perishable strata (p. 88). But where the streams cross the outcrop of harder beds, as, for example, the Hydraulic Limestones of the Lower Lias, their flats become narrow and sharply defined (p. 26). Besides the alluvium of the streams, there is a wide flat of about 3 square miles in the Keuper country west of Bunny, including Gotham Moor, Ruddington Moor and Bunny Moor, which appears to have formed the site of a shallow lake, and probably persisted as an occasionally flooded bogland until artificially drained. This tract is the largest patch of alluvium in the map. Previous Literature. As the area possesses no formations that are peculiar to it, and as its strata are very sparingly exposed save in the workings of gypsum in the Keuper, of the hydraulic limestones in the Lower Lias and of the ironstones in the Middle Lias, its geology has not attracted much attention, and the literature is therefore somewhat scanty. So much of the eastern portion as fell within Sheets 64 and 70 of the Old Series Map was described in detail in previous memoirs of the Survey accompanying these sheets, and an account of some of the ground in the southern part of the map (partly reproduced in the present work) was incorporated by Mr. C. Fox-Strangways in his Survey memoir on the adjacent .New Series sheet published in 1903 ; (" Leicester," Sheet 156). A short account of the Jurassic rocks of the district is contained in the general memoir on the Jurassic Rocks of Britain, vols, iii and iv, by Mr. H. B. Woodward. By independent observers there have been special descriptions of the more interesting local developments of particular formations within the district ; among these may be mentioned important papers on the Rhsetics, by E. Wilson and H. E. Quilter ; on the Lower Lias and its fossils, by H. E. Quilter ; on the Middle Lias Marlstone, by E. Wilson ; and on the Glacial deposits, by R. M. Deeley. To these papers full references are given in subsequent pages and in the Bibliographical Appendix (pp. 108-9). The interesting series of fish^ reptile and insect remains obtained from TABLE OF FORMATIONS. the cementstone quarries at Barrow-upon-Soar have furnished the subject-matter for several papers of descriptive palaeontology, to which, again, references are given in the Appendix. Besides these specialized works, the main outlines of the geologi- cal features of the district have been described incidentally in the more generalized articles on the geology of Nottinghamshire and Leicestershire referred to in the Appendix to this memoir. Table of Formations. The following formations, briefly described in the foregoing pages, are represented on the map : — Superficial Formations. Recent Pleistocene H f Post-glacial - Late-glacial Jurassic Inferior Oolite. Glacial - - Solid Formations. Lincolnshire Limestone - - Alluvium. - River-gravels, loam, etc. - Older river-gravels, loam, etc. f Sand and gravel. _) Boulder Clay, with ~\ brickearth or ( loam. Pale limestone. ( Lower Estuardne Pale laminated clay Northampton ) Series. and sand. Beds. J Northampton ( Sand. ' Upper Lias Lias Middle Lias - L Lower Lias fRhartic Teiassic . Keuper Marl Ferruginous sand- rock. Dark shaly clays. ' Ferruginous lime- stone, ironstone and calcareous sandstone (Marl- stone). . Sandy shales and t clays. Shaly clays with thin limestones. f Black and grey \ shales with thin ■■{ lenticular lime- stone in upper part. 'Red, green, and mottled marls with thin sand- stones and gyp- sum. CHAPTER II. CONCEALED CARBONIFEROUS AND OLDER ROCKS. 1 While the Keuper Marl is the oldest formation to reach the surface and therefore to be shown on the map, some evidence is forthcoming from deep borings in the NW. part of the sheet respecting the buried floor of older rocks beneath the Trias. In the Soar valley, south of Quorndon and only just across the southern margin of the map, the Pre-Cambrian granitic rocks of Mount Sorrel come to the surface from beneath a mantle of Keuper Marl. In the same valley near Hathern, 3 miles SW. of East Leake, two borings 2 passed from Trias into the Pre-Cambrian " Charnwood Forest Rocks " ; but in borings at Ruddington, Owthorpe and Edwalton, to the east of the Soar valley, the Trias was found to rest on Coal Measures. These are the only places at which the Palaeozoic and older rocks have as yet been proved within or in the proximity of the area included in Sheet 142. The Ruddington boring commenced in Keuper Marl and entered the Coal Measures at a depth of 687 ft. below the surface. The character of the measures above and below one of the coals at 1072 ft. in depth proves this seam to be the Alton ; and its identi- fication is corroborated by the nature of the shale roof, in which Mr. R. D. Vernon has recently found the marine fossils character- istic of this horizon throughout the Derbyshire Coalfield. 3 At 1131 ft. the boring entered the First Grit of the Millstone Grit Series and was continued to a total depth of 1870 ft. 4 in., the last 109 ft. being bored in the Kinderscout Grit of the same series. 4 Here again, as in the case of the measures above and below the Alton Coal, the sequence closely resembles that recognized in the Derbyshire Coal- field. There can indeed be no doubt that the boring enters the Derbyshire Carboniferous sequence below the horizon of the Kilburn Coal (550 ft. above the Alton), and that it was sus- pended before reaching the Limestone Shales. The Coal Measures represented therefore fie many feet below the Middle Coal Measures of Derbyshire where over 1000 ft. of strata separate the Alton Coal from the Black Shale or Silkstone Coal which is there taken as the base of the Middle Coal Measures. 6 1 By W. Gibson. 2 " The Geology of the Leicestershire and South Derbyshire Coalfield." Mem. Geol. Surv., 1907, pp 358-359. 3 " Geology of South part of the Derbyshire and Nottinghamshire Coalfield." Mem. Geol. 8wrv., 1908, p. 100. * For further details see the abridged record of the boring in Appendix I, p. 105, of this memoir, or the fuller section given in "The Geology of the Country between Newark and Nottingham." Mem. Geol. Swv., 1908, Appendix I. pp. 112-113. • " Geology of South part of Derbyshire, etc., Coalfield," p. 60. 10 CONCEALED CARBONIFEROUS AND OLDER ROCKS. At Owthorpe, 6 miles east of Ruddington, the Coal Measures were entered at a depth of 1069 ft. ; and after passing through several seams of coal the boring was discontinued at a depth ol 2032 ft.' In this sequence the fossil-evidence and character oi me strata prove them to belong to the measures above the Black Shale Coal of Derbyshire. Unfortunately the identification of the seams of coal passed through is not fully established, though there are reasons for taking the coal (4 ft. 8 in. thick) at 2012 ft. in depth to be equivalent to the Top Hard Coal of the Nottinghamshire Coal- field. 2 If this determination be correct, the position of the Alton Coal at Owthorpe should be about 3400 ft. below O.D. as com- pared with 972 ft. at Ruddington. Supposing there is no faulting, the dip between the two localities amounts to over 1 in 15, or a little under 4 degrees. Owthorpe, however, is not situated in the direction of full dip with respect to Ruddington, for in a boring | mile NE. of Edwalton Church and 3 miles NE. of Ruddington, the Alton Coal lies approximately 2200 ft. below O.D. The inclination between Ruddington and Edwalton is therefore about 1 in 13 or a little over 4 degrees. From the estimated depth to the Alton Coal at these three points we may deduce that the strike of the Carboniferous rocks is roughly N30W. If this direction is maintained to the SE., the Coal Measures should be present beneath the Secondary rocks over the whole area east of a line joining Ruddington and Melton Mowbray, but the depth to the productive seams would be great within the outcrop of the Middle Lias and Oolites. It must be acknowledged, however, that the determination of the strike of the Carboniferous rocks between Ruddington and Owthorpe is based on somewhat slender evidence. If reliable, it would lend support to the conclusions reached by Prof. P. F. Kendall as to the southerly extension of the Nottinghamshire Coalfield beneath the Secondary formations of Leicestershire and Rutlandshire. 3 In his report to the recent Commission on Coal Supplies, Prof. Kendall postulates an extension of the Coal Measures up to the margin of the Fen country and therefore far beyond the south- eastern limits of the present map. This extension is based on the connexion existing between the distribution of the Carboniferous rocks and the Charnian ridge, of which the strike agrees with that of the Coal Measures as deduced from the Ruddington and Owthorpe borings. In calculating the future coal supply, however, the Commissioners limit the probable extension of the concealed coalfield to about the latitude of Melton Mowbray, though they recognise that the arguments advanced by Prof. Kendall are based on the only data at present available. 1 See Appendix I., p. 104, and " Geology of tbe Country between Newark & Notting- ham." pp. 106-8. 2 " Geology of the Country between Newark and Nottingham." Mem, Geol Stirv lyoo. p. its, i«7. ' " Final Eeport of the Royal Commission on Coal Supplies." Part IX 1905 p. 19, and pp. 24-28, ' f UNDERGROUND STRUCTURE. 11 While the evidence as to the composition of the pre-Triassic platform is very scanty, the shape of the buried surface is still more problematical. Between Ruddington and Owthorpe, and again between Ruddington and Edwalton, its slope appears to be gentle ; the general direction of fall -being eastward. Analogy with the proved pre-Triassic surface in the concealed coalfield between Nottingham and Doncaster favours the idea that north-east of a line joining Ruddington and Melton Mowbray the concealed Palaeozoic surface has similarly a slope to the east at a gentle angle and does not present those irregularities met with around the Leicestershire Coalfield. 12262 A 3 12 CHAPTER III. TRIAS. 1 Keuper. general account. This division of the Trias is represented on the present map by the upper part of the Keuper Marl only, the lower part of the Marl and the Waterstones outcropping in the area to the north (Sheet 126). It occupies the north-western part of the present sheet, with an interrupted extension along the northern margin of the map as far eastward as Langar ; together with a tract in the southwest, in the valleys of the Soar and Wreak, where however it is greatly obscured by drift and alluvial deposits. The Keuper is known from the first Owthorpe 2 boring, which penetrated the whole of the formation, to be 748 ft. thick at that place, of which 121 ft. is referred to the Waterstones and 627 ft. to the Keuper Marl. The Ruddington 3 boring commenced below the top of the Keuper Marl and passed through 386 ft. of Marl and 73 feet of Waterstones. The thickness of the Keuper Marl which actually outcrops in the district we are describing, is probably between 300 and 350 ft. The dip of the beds can rarely be ascertained by direct observation, but, estimating from the known thickness, the width of the outcrop, and the inclination of the overlying rocks, it appears to average about 1° to the SE., though it is doubtless affected locally by the small undulations recognizable in the Lias. No fossils are known from the Keuper of our present district although a few have been recorded from near Leicester, 4 where they were chiefly found in a local development of the ' Upper Keuper Sandstone,' and include the relics of reptiles, fish and plants. The physical aspect of the country is somewhat different from that of the Keuper area north of the Trent, owing to the com- parative rarity of the sandy rock-bands or ' skerries ' so prevalent in the lower part of the Marl. Instead of the regular features produced by the skerries the country is irregularly undulating, with occasional conspicuous hills, usually crowned by patches of sandy drift. The rock is, typically, of a decided red colour, and has a clayey texture though very largely composed of fine siliceous silt with an admixture of calcareous and clayey matter. Usually it breaks up into angular pieces with the characteristic 'marly' fracture, and in dry weather is reduced readily by agricultural operations to a loamy soil. Where well exposed, its bedding is usually distinct and is accentuated by the presence of green streaks and bands The 1 By R. L. Sherlock and B. Smith. ' " Geology of the Country between Newark and Nottingham " Mem r»»i c, 1908, pp. 24 and 106 See aUo Appendix I. of present? mSTlof ^* S * m ' 3 low.. DD. 24 and 112. Sep, nJ.sn n ins n f ™„„-.j. • ' v "*• -.-._., „,.. . "i-" "-"-v v . ™ uj. jjreseni; memoir. KEUPER MARL. 13 green bands are sometimes marly, but more generally are composed of fine loamy sand or silt. The skerry-sandstones, as already mentioned, are relatively scarce in this part of the marl, and the only example which could be traced out on the map occurs near Glapton. Gypsum beds of economic importance occur at two horizons. The higher, which is mined and quarried 1 mile NE. of Owthorpe, is on the horizon of the Newark deposits, i.e., near the top of the red marls ; the lower, mined at Sharpley Hill, East Leake, lies at about 180 ft. below the Rhaetic. The uppermost 15-30 ft. of the Keuper Marl throughout the area is of a pale green, or greyish, colour. This ' Tea-green Marl,' as it is called, was, at one time, classed with .the overlying Mhsetic, which was included with the Lias. The classification now adopted, by which it is united with the Keuper, was established, in this district, mainly by the researches of Edward Wilson 1 , who confirmed the views as to its relationship arrived at in other parts of the country by Dr. T. Wright 2 and others. Except in colour the Tea-green Marl does not differ from the red marl below, and it is generally considered that the difference in colour is due to subsequent chemical change. 3 It possesses, however, a more persistently massive homogeneous structure than most parts of the red marl, and its fracture, in consequence, is usually conchoidal or spheroidal in unweathered sections. In the present area the Tea-green Marl forms the lower part of a prominent escarpment, crowned by Khsetic and Lias, or by drift. Its thickness appears to be about 30 ft. between East Leake and Clipston, but diminishes somewhat when followed north-eastward. Some topographical details will now be given respecting the outcrop of the red marls, which for this purpose will be divided into a north-western area and a south-western area. The Tea- green Marl will then be dealt with under a separate heading. North-western Area. — One of the best sections in the Keuper Marl of this area is exposed by the Great Central Railway, which, at the northern limit of the map, runs through a cutting about 24 ft. deep, showing the following details :— Bed marl and talus ' Skerry ' sandstone Bed marl, unusually sandy 1 Skerry ' sandstone Bed marl, laminated 1 Skerry ' sandstone, grey and laminated ... Talus North of Clifton the country has a loamy pebbly soil, due to the remains of sandy drift, and also partly to the outcrop of small skerry bands. At the sharp •"The Rhsetics of Nottinghamshire. - ' Quart. Journ. Geol. Soo., vol. xxxviii. 1882, p. 451. 2 " On the Zone of Avicula contorta and the Lower Lias of the South of England." Quart. Journ. Geol. Soc, vol. xvi., 1860, p. 374. 8 Recently, however, Dr. Moody has upheld the view that it is the green colour which is original, and that the redness of the underlying beds is due to secondary change. (" The Causes of Variation in Keuper Marls and in other Calcareous Rocks," Quart. Journ, Geol. Soo,, vol. lxi., 1905, p. 431.) ft. in 7 2 6 5 1 2 6 2 7 14 TRIAS. bend in the road to Ruddington, south of Glapton, there is a gully, about 12 ft. deep, in red marl with a 4 in. skerry and some green marly bands. The skerry, indicated on the map, may be traced by its surface-feature and its debris in the, ploughed land, into Clifton Pasture, where it is masked by drift. The sharp rise at Glapton Wood appears to be composed of red marl to the summit, and there is no indication that the prominence is due to the presence of a skerry. In the much-obscured railway cutting at Edwalton, a band of white sandrock, about 18 in. thick, dipping gently to NW., was noticed near the Nottingham road, and other traces of the same rock were seen in the vicinity. Prom Ruddington and Bunny to Plumtree and Normanton there are no sections deeper than a few feet. Much of the country has a loamy soil, especially along a belt between Ruddington and Flawf orth House, which may be due to the outcrop of a skerry, while other parts are modified by the weathering of patches of sandy drift. From Tollerton and Clipston to Plumtree the soil is red clay, and numerous small sections of red marl may be seen in the banks of the brook flowing through ^Tollerton. The highest beds of the red marls crop out in the lower slopes of Hoe Hill, where they plough up as stiff clays. On the NW. side of the hill some fragments of hard skerry and lumps of gypsum were thrown out from the bottom of a well sunk at the junction of the green and red marls to a depth of about 35 ft. The gypsum here corresponds to the position of the Newark deposits. The broad tract of alluvium extending from Bunny to Gotham rests on Keuper Marl with some sandy drift intervening, and there are indications that the belt of gypsiferous strata worked at Gotham and East Leake outcrops beneath this alluvium. Between Bunny and Costock, at the 8th milestone from Nottingham, a brick- yard in the upper part of the marls shows 2 ft. of red clay resting on a lenticle of green sandy marl having a maximum thickness of 1£ ft., and this lies on red marl exceeding 25 ft. in thickness without any admixture of skerry. The brickyard is cut into a terrace-like feature which is often visible at the foot of the Rhastic escarpment, but which comes in and dies out again rather suddenly and is not strictly parallel to the escarpment -behind it. The only evidence as to the origin of the feature is afforded by the above-mentioned section, where the sandy band may represent the horizon of a sandstone which occasionally becomes capable of forming a terrace. The wood NE. of Stanford Hills Farm is known as Brickyard Spinney, and small excavations in it indicate that clay for bricks has formerly been dug here. R. L. s. Near the northern margin of the map the highest part of the red marls is well exposed at the Cotgrave Brickyard, 450 yds. SSW. of The Gripps, where the excavation into the hillside has reached back almost to the base of the Rhaetic which here forms the top of the escarpment. The section exposed in 1 906 was as follows : — ft. Tea-green marl seen to 16 Red marl , ... 9 Thin green. band with skerry Red marl ... ' „. ... ... ... ... ... 6 Thin green band with skerry forming the main floor of quarry Red marl with ' balls ' of gypsum 12 ' ... ... 43 The ' balls ' of gypsum occur at some 24 ft. below the Tea-green Marl, being approximately at the horizon of the gypsiferous beds at Newark. The bands of skerry seen in the section do not cause any surface features. ■■ The largest exposure of the Keuper Marl in this part of the map is that revealed in the workings of the Snaith Plaster and Cement Co. S of Cropwell Bishop (Sheet 126), on the E. bank of the Grantham Canal 600 yds. N of the bridge at Blue Hill, Gypsum was first raised here by quarrying, but it is now ' chiefly extracted by horizontal galleries driven along the more promising beds. late KtherH^Vaa* 116 deeP6 - W ° rkingS Were U1 * d ertaken at the suggestion of the KEUPER MARL. 15 The open pit shows the following section : — Red marl ) .,, * „ „ Green marl }- wlth balIs of gyP Bum ... ... Bed marl occasionally mottled green, with 5 or 6 beds of gypsum White gypsum roof , stained blue-green ... to Red marl White gypsum floor, often stained blue-green ... to ft. in, 1 4 3 6 30 6 1 3 4 1 3 about 42 Gypsum over 1 ft. thick occurs below the floor of the pit. - The lower part of the section is practically identical with that of the Gotham Plaster Company's working just N. of the limits of the present map, described in a previous memoir. 1 The white gypsum floor is reputed to be the equivalent of the deposit which gives th$ most profitable yield at Newark. The balls of gypsum, occurring in the upper few feet of the section, that is, about 20 ft. below the base of the. Tea-green Marl, vary in size from an average of 6 to 10 ft. in horizontal diameter, to a maximum of 14: ft., and their occurrence is quite sporadic. They are much valued because of the high quality of the gypsum in their interior. They are located by the workmen by means of boring or probing, and are then reached and extracted by sinking circular pits. The balls usually have somewhat the outlines of a plano-convex lens, resting upon its flat base. The clean crystalline gypsum of the interior of the ball passes outward into a mixture of marl and gypsum;; which changes laterally into the ordinary marl. The marl occurring on the horizon of the balls is said to abut against their convex surfaces, and not to be moulded upon orarched up by them, but no opportunity was found of confirming this observation. The two beds forming the roof and floor of the tunnels are generally of massive gypsum, often stained pink and bluish-green by incorporated marl, but they occasionally become fibrous and platy, forming what is known to the Workmen as ' mother,' and occasionally they tail off in thin vein-like strings. The higher and thinner bands show similar variations in a more pronounced degree. In the fibrous 'mother' the fibres are always vertical, whatever may be the inclination of the plate or vein itself. b, s. Tfie Spitth-western Area.-^—A. disused brickyard at the foot of Sutcliffe Hill, Rempstone, shows 8 feet of red marl. Small pockets of sandy gravel and green clay are let down into it near the top and indicate the origin of the loamy pebbly soil which so frequently caps the Keuper Marl. Between the Nprmanton Hills fault 2 and Stanford upon Soar the soil is a red clay modified by sandy downwash from the drift which caps the Hoton Hills, About 7 ft., of red marl may be seen in the roadside 200 yds, N. of Underhill Farm, and on the rising ground south of the King's Brook there are some large disused marl-pits without sections. The little valley between Hoton Hills and Hoton has been excavated through the drif trplateau into the Keuper ; and at the intersection of roads N. of the village, a small pit shows 18 ins. of red clay soil overlying 18 ins. of greenish- grey skerry, which rests on red marl. It will.be seen from the map that southward from Cotes the Keuper Marl ig only exposed in a narrow belt on the slopes of the valleys, between the plateau- drift and the alluvial terraces of the rivers. Even this limited outcrop is generally masked by hillwash, so that it is only in an occasional brickyard or marl-pit that the marl is actually seen. The best exposure in this tract occurs at the small brickyard situated at the end. of a low spur 300 yds, NE. of Walton Grange, which reveals about 20 ft. of red marl with an irregular capping of drift gravel up to 4 ft. in thickness. A lumpy band of gypsum is visible at the bottom of the pit and its outcrop can be I " Geology of, etc., Newark and Nottingham." Mem. Geol. Surv., 1908, p. 52. See" Geology of the Country between Derby . . . and Loughborough." (Sh. 141.) Mem. Geol, Surv,, 1905, p. 48 ; also present memoir, p. 17. 12262 A * 16 . . TRIAS. followed for about J mile in either direction by the. traces of old excavations from which the mineral has been dug. It is probable that the gypsum is on the horizon of the bands worked near East Leake and Gotham, and that it is below the horizon of the Newark deposits. In the Wreak valley the Keuper Marl is brought in on the south, between Cossington G-orse and Rotherhy, by the Barrow and Sileby 2 fault. The fault is readily distinguished, where it crosses the Ox Brook, Thrussington, the blue Liassic clays and limestones being here thrown against redand grey Keuper marl in the stream section. . . Except at this place and in the bottom of the little valley 500 yds. SE. of Cossington G-orse, the outcrop of the Keuper is obscured by drift or by the valley deposits. r l s Tea-green Marl. — In the north-easterly portion of its outcrop in the map, between Langar and Blue Hill, NW. of Colston Basset, the Tea-green Marl is poorly exposed, but its limits are readily traceable by the physical feature ; by the colour and character of the soil ; and by- the occurrence of small springs which issue from the base of the Rhsetic beds. These springs have been frequently utilized as the sites for wells and ponds, which partly conceal their points of issue. Several occur north of the scarp at Langar and feed the Fish Ponds at Langar Hall. In an old brickyard 200 yds. NE. of Blue Hill, at the base of the Rhsetic feature, bricks were made from Tea-green Marl, which is still sparingly visible in the overgrown excavation. A good spring from which the water supply of Home Farm near Colston Basset is drawn, is thrown out by the Marl, which appears to have a maximum thickness of about 15 ft. in this part of the district. Its thickness increases westward, however, as in the section at Cotgrave brickyard, as previously described, not less than 16 ft. of the Tea-green Marl is exposed, and we must allow about 4 ft. more to reach to the base of the Rhsetic shales. The outcrop SW. of this exposure is much obscured by drift, but the green bedB are again clearly seen W. and S. of Blackberry Hill, and they are probably thicker here than at Cotgrave. They are visible in several places in the banks of the little stream S. of Blackberry Hill, extending up to a few yds. E. of the road- crossing, while immediately above this point fragments of Mack Rhsetic shales were found in the banks. In the next little valley to the south the junction between the Tea-green Marl and the Rhsetic black shales is marked by a spring 200 yds. NNW. of Hill Farm. In both valleys the marl forms gently sloping ground beneath the steeper slope of the Rhsetic beds, and it gives rise to the characteristic grey or yellowish-grey- clay soil. B. S. _ In the Mid. Ry. cuttings SE. of Plumtree Station, the green marl is still visible under the drift, though the section is now much obscured (see p. 77). The road from Plumtree to Stanton also reveals tflfe green marl in a cutting to a depth of about 15 ft. No other noteworthy section occurs until we come to the accommodation road S. of Keyworth, on the east of which the bed is sparingly exposed in some old marl-pits. : In the valley of the Fairham Brook the outcrop of the green marl is much obscured by drift. West of the brook it resumes its normal aspect, forming the lower and steeper part cf the combined Rhsetic-Lias escarpment. For over 3 miles however, the escarpment is covered by thick plantations, and the onlyevidence lies in the character of the soil and in an occasional ditch section. The valley between Crow Wood and Sharpley Hill; through which the Great Central Railway runs, cuts almost, but not quite, through the green marl, which can be seen in the railway-cutting and in pits by the roadside. On the S. side of East Leake Hills the prominent feature persists for some distance, until, east of Taft Leys, the outcrop rapidly expands and swings in a broad belt across the valley rising again into an escarpment on the southern slope. Here, however it soon becomes overlain by drift and does not reappear at the surface until we reach Rempstone, where it is exposed in a pit near the crossroads and in the bed of King's Brook. In this quarter the outcrop is shifted westward by the more northerly of the pair of faults shown on the map, and the green marl is next seen in the brook, alongside the artificial lake in Stanford Park. ' We were informed that the lake is 17 ft. deep and has a floor of green clay. As red mart 68°' Fox ~ Stl ' 8Ilgwa y s ' ' yeol °gy ° f th « Country near Leicester.' Mem.,Geol. Surv., 1903, RH^TIC. 17 is exposed in the bank on the N. side of the lake, we must assume that the Keuper possesses a somewhat high dip in this locality, which may be accounted for by the proximity of' the fault. An unfinished well beside the high road opposite the lodge at the NE. corner of Stanford Park had, in 1906, been sunk to a depth of 42 ft. in red marl, and proved the absence of the Tea-green Marl there. The more southerly or Normanton Hills fault cuts off the outcrop of the green beds, along with that of the Rhaetic, and carries it south-eastward into an area thickly covered by drift. Where the base of the Rhaetic again emerges, in the valleys between Burton-on-the- Wolds and Barrow-upon-Soar, the ground is much obscured by downwash, but the green marl is visible in the bed of Walton Brook, NE. of Walton ; in a few places on the slopes of Barrow Hill ; and in the Mid. Ry. cutting 600 yds. NW. of Barrow Station. On the N. side of the Wreak valley the Tea-green Marl is cut out by the Sileby Fault. b. l. s. Rhaetic. general account. The Rhaetics are divided by their lithological characters into the ' White Lias ' above and the Avicula contorta Shales below, but these subdivisions are too thin to be shown separately on the map. The lower beds of the Rhaetic consist of black paper-shales with thin sandy bands. Locally they are very fossiliferous and often include a bone-bed containing fish and reptilian remains. The junction of the Rhsetic with the Tea-green Marl, though rarely exposed, is always sharply marked. There may indeed be a slight unconformity at this horizon, as it has been observed that in some cases there is evidence of the green marls having been eroded before the overlying beds were deposited. 1 The White Lias 2 consists of thick-bedded light-coloured marls with which are interbedded a few thin bands of compact argillaceous limestone, usually more or less nodular and disconnected. One of these limestones — a very fine-grained hard splintery rock — forms the top of the division. This band was formerly used for road- metal, and the traces of the old shallow pits from which it was obtained are of much aid in tracing its outcrop. The nodular limestones are blue-hearted, but often stained purple on the outside to a depth of an inch or two. They fall to pieces so readily when tapped with the hammer as to suggest that they are in a state of internal strain. Microscopically, they are found to be composed of highly calcareous mud, containing a small quantity of pyrites, a few clastic grains of quartz and some flakes of mica. When treated with acid they leave a considerable amount of insoluble residue, which is probably, in part, colloidal silica. The thickness of the formation is variable but always small. At Barnstone (Sheet 126) the black shales are 14 or 15 ft. thick, and the White Lias is about 18 ft. ; at East Leake the railway-cutting through the Normanton Hills, just over the western boundary of the map, showed about 20 ft. of the dark shales, overlain by grey shale with thin limestone, of which 12 feet was assigned to the i " The Rhsetics of Nottinghamshire." Quart. Jowrn. Geol. Soo., vol. xxxviii., 18S2, p. 455. 2 Since the above was typed, Mr. L. Richardson haB thrown doubt on the equiva- lence of these Midland beds with the ' White Lias ' of Somerset, and classes them simply as " Upper Rhtetics." (" The Rhaetic Section at Wigston, Leicestershire," Geol. Mag., dec. v., vol. vi., 1909, pp. 366-70.) 12262 B 18 TRIAS. Rhjetic, but which passed up into the Lower Lias with no good line of separation between them. 1 The beds are always, as in the last-mentioned section, con- formable to the Lias* above, and have a slight general dipoi 1 or 2 degrees towards the SE., but with gentle undulations which alter the direction locally. , The outcrop is marked by a prominent escarpment which becomes bolder as it is traced south-westward, owing to the increasing participation of the Keuper Marl in the feature. But between Clipston and Widmerpool the escarpment is often obscured by drift, as also between East Leake and Rempstone, and again south of the Normanton Hills fault. The fossils of the Rhastic, though in places individually numerous, belong to a limited range of species, chiefly bivalve shells (lamelli- branchs) of small size, and fragmentary fish remains. The best collections have been obtained from localities just beyond the Limits of the map, at Barnstone 2 on the north, and at Normanton Hills 3 on the west. A few species which have been recorded from the Stanton railway-cutting or collected during the course of the recent survey are mentioned in the following detailed description of the series. E. L. S. & B. s. DETAILS. The Rhaatic Beds are very scantily exposed along their northern outcrop west of Langar ; but here and there the black shales, or the grey marls and fine- grained limestones of the White Lias, have been disclosed in wells and ditches. The best exposure is that seen in a quarry opened on the left bank of the Grantham Canal at Blue Hill, to obtain clay for puddling, where the following section was measured : — Made ground Brown soil with stones ' Thin band of purple-blue rather crystalline limestone with Modiola minima... ... ... Blue-brown calcareous shales with ' race ' Band of thin concretionary limestone... Yellowish creamy calcareous shales with ' race ' Creamy fine-grained concretionary limestone Calcareous shales Nodular creamy blue-hearted limestone Blue-yellow calcareous shales, stained red Fine-grained creamy and blue-hearted septarian lime- stone, passing laterally into shales. Fink-purple staining outside. Manganese (dendritic) markings Grey-blue clays and marls, stained brown and red ... Blue-grey somewhat concretionary clays and marls with manganese stains, gypsum crystals, and fossils 7 Black fossiliferous shales at water level ; weathered yellow on bedding planes ; containing, cf . " Pul- lastra" arenicola Strickl. and Schizodus concentricus t Moore 1 1 White Lias' Et. ins. 4 6 4 1 1 9 2*- 9 3-6 1 6 2 19 6 1 " The Geology of Derby, etc., and Loughborough.'' Mem. Oeol. Surv., 1 905, p. 35 ; and M.Browne, Rep. Brit. Assoc-, for 1895, p. 689. 2 See " The Bhsetics of Nottinghamshire," by E. Wilson, op. supra cit. ; and " The Geology of the Country between Newark and Nottingham." Mem. Geol, Surv 1908, p. 55. s See Browne, Ben. Brit. Assoc, for 1895, p. 689, and " The Geology of Derby, etc, and Loughborough. Mem, Oeol. Surv., 1905, p. 35. KHiETIC. 19 This section does not extend quite to the top of the Rhsetic, which is clearly exposed, however, in a small pit at Cotgrave Gorse, presently to be described. The Canal-cutting, of which the above section forms part, has crossed all the strata from the top of the Keuper (Tea-green Marl) to the Hydraulic Lime- stones of the Lower Lias, but except at the quarry is now much obscured. The following generalized section has been constructed from the evidence still available. Fig. 2. — Section through the Rhsetic Escarpment at Blue Hill, Nottingham and Grantham Canal. (B. Smith). Length of section, 220 yds. Vertical scale, about 2 x horizontal. Canal Bridge. Quarry. 4. Made ground. 3. Lias shales and limestones. 2. Shales and marls, with concretionary limestones (White Lias). 1. Black fossiliferous Rhsetic shales. At the northern end, in the quarry, the dip is about 3° in the line of section. South of the quarry the Lias Limestones come on, well bedded and fossiliferous. North of the landing-stage they rest on a few feet of shale, below which are blue marls associated with nodular masses of compact fine-grained limestone showing a conchoidal fracture. These marls and nodular limestone represent the top part of the Rhsetic, not seen in the quarry, and they add about 4 ft. to the thickness of the ' White Lias ' given in the previous section, making about 17 ft. in all. The marls are often contorted and compressed laterally ; they enclose small nodules of limestone and irregular hollow lumps of calcareous ' race,' and when weathered, contain numerous small crystals of gypsum. On the NE. side of Cotgrave Grorse occurs the previously-mentioned pit showing the Junction of the Lower Lias and Rhsetic, the section being as follows : — ft. ins. Soil, with irregular pockets and 'pipes' of red sand 6+ f Two thin bands of pale yellowish limestone and shale : Lower J spines of echinoderms in the limestone 4 Lias. 1 Band of blue limestone with shelly layers 7 LSbale ... 1 3 'White (Compact fine-grained limestone; blue hearted, with Lias.' \ purplish exterior ; splitting with conchoidal fracture 1 7 4 The quarry lies a few yards to NE. of a small fault, trending through Owthorpe and Cotgrave, which brings up the Rhsetic on the SW. against Lower Lias, and sets back the escarpment some 200 yds. to SE. Drains cut in the face of the hill in the Long Plantation reveal at intervals glossy black Avicula- shales and grey shaly marls with ' race.' In the neighbourhood of Clipston the outcrop is obscured by drift, but at Blackberry Hill the Rhsetic beds emerge again and resume their characteristic surface features. Similar features are observable in the valley N. of Stanton Tunnel, where the base of the Rhsetic is marked by a copious spring as noted previously (p. 16). b. s. Though no definite evidence was found, the position of the isolated Hoe Hill, I mile SW. of Clipston, and the height of the feature above the base of the Tea- green Marl, render it likely that the hill carries a small outlier of the Rhsetic shales under its thin capping of drift. This outlier probably marks the extremity of a spur-like westward projection of the Rhsetic, due to a shallow east-west fold, like the similar features farther S., at Rancliffe Wood and Hotchley Hill. 12262 B 2 20 TRIAS. 60 2i The Midland Railway cutting and tunnel at Stanton-on-the- Wolds exposed a good section in the Rhsetic, which, although now obscure, was carefully ixamined at the time by E. Wilson, 1 who recorded the following details of it :— ft. in. "Boulder-clay with local intercalations of drift- sand 50 ft to 'Shales dark coloured, thickly laminated, with a few thin seams of sandstone and a band of nodular limestone 1 ft. 9 in. from base : Cassianella con- torta, Axinus elongatus, Protocardium Philippianum Pyritic sandstone 5 in. to Shales darker and more thinly laminated than the overlying, with occasional streaks of fine white sand : C. contorta, A. elongatus, P. Philippianum... Pyritic limestone, with A. elongatus, Modiola minima, fish scales, sun-cracks J in. to Shales black, fissile, with thin streaks of fine grey sand 9 in. to Bone-bed or coprolite seam, soft white sand and quartz-pebbles : spines of Nemacanthus filifer, and Hybodus, sp. ; teeth and scales of Saurichthys acuminatus, Hybodus minor, B. reticulatus, Hybodus sp., Acrodus minimus, Sargodon tomicus, Ceratodus altus, Gyrolepis tenuistriata, and various cestraciont palatal teeth ; teeth and coprolites of Ichthyosaurus platyodon, Ichthyosaurus sp.., and other reptilian and piscine teeth, vertebrae, bones and coprolites ... Shales black, fissile, and earthy_ layers alternating ... Coprolite-seam, earthy ; coprolites at wide intervals... Shales black, laminated, with occasional reptilian bones Avicula- contorta shales (Rhsetic). Tea-green Marls (Upper Keupee). 3 1 10 1 Light-blue marls weathering yellowish-green and breaking up into cuboidal fragments ; base not seen 1 3 20 The Upper Rhsetic marls were not seen in situ ; but limestone nodules with Estherice were found in the overlying drift." A cutting near Plumtree, a mile further north on the same railway, still obscurely shows black Rhsetic shale resting on Tea-green Marl and covered by drift. The shattered appearance of the shale, its outlying position relative to the main Rhsetic mass, and the known disturbance of the beds by glacial agency in an adjacent section (see p. 77), render it uncertain whether the shale is in situ or has been glacially transported ; but, in the latter case, it cannot have been removed far from its original position. After leaving the railway the Rhsetic is not again exposed until Keyworth Wolds are reached, where it appears at one spot to reach the surface. The position of its outcrop under the drift is doubtful, but a deep well 800 yds. S. of the fork in the road from Keyworth to Widmerpool passed, through 47 ft. of boulder-clay directly into Tea-green Marl, thus proving the absence of the Rhsetic at this point. When it again emerges from under the drift near North Lodge its feature can be followed down to the Pairham Brook, where the flinty lime- stone band, which is taken to mark its upper limit, is laid bare in the bed of the stream. Its position in the escarpment which sets in again a little W. of the brook is indicated by numerous small pits, where the flinty limestone has been dug in the past for use as macadam. A few feet of shale resting on the Tea- green Marl may be seen a mile S. of Bunny in the side of the Loughborough road, but apart from this section there are no exposures until the outcrop is followed round to Costock. Here, in a dry season, the flinty limestone and some other bands of similar limestone below it are visible in the bed of the stream near Field Farm. South of the stream the Rhsetic is indicated only by the presence of several of the old limestone jits ; and at Sheepwash 1 " The Rhaetics of Nottinghamshire." Quart, Journ. 6ml. Soc, vol. xxxviii., 1882 p. 454. RH^ETIC. 21 Brook it becomes covered by drift and does not again emerge before it is cut off by the Stanford Hall fault. It must, however, outcrop under the drift near Lings Farm, and running round the small valley of the brook from Bempstone, it forms part of the marked escarpment of Sutcliffe Hill. The place where it crosses King's Brook is marked by the presence of the flinty limestone in the stream-bed. The Rhsetic is never seen in the trough of the pair of faults running through Stanford Park, but its position is marked by the feature. The Normanton Hills fault throws its outcrop about 2 miles eastward, under the boulder-clay of the plateau. r. l. s. The junction of the Bhaetic with the Tea-green Marl was seen in Walton Brook, where a few inches of dark laminated shale rested on the green marl without the intervention of a bone-bed. On the southern slope of the valley of Walton Brook, the black shales were proved in a well, 500 yds. WSW. of Walton Church, and the base was seen resting on Tea-green Marl in the road- cutting on Barrow Hill a little further on, the dip being southward at 2°. Here a bone-bed was present. The best sections of Rhsetic in the southern area are at Barrow-upon-Soar, where the Bhaetic escarpment, running along the NE. side of the Soar valley, is cut through by the Midland Bail way, showing laminated lumpy shales resting on Tea-green Marl. By the roadside, 600 yds. SE. of Netherfleld, grey shale with nodular limestone, representing part of the White Lias, was seen in a small quarry. The dip is here northward at 12°, owing to the proximity of the Barrow and Sileby faults. c. f. s. 22 CHAPTER IV. LOWER LIAS. 1 GENERAL ACCOUNT. The outcrop of the Lower Lias occupies more than two-thirds of the area of the map, covering the whole of the Yale of Belvoir and swinging round southward, under a thick capping of boulder- clay, into the Wreak Valley, which, E. of Hoby, lies entirely within this formation. Its thickness in the district is estimated to be about 670 ft., calculating from the available data. This exceeds by about 30 ft. its proved thickness in a well-boring at Grantham, 2 7 miles E. of the NE. corner of the map, but is 80 ft. less than its thickness farther southward, in Sheet 156. 3 In the Vale of Belvoir, where its whole outcrop is exposed, the Lower Lias may be conveniently separated by lithological characters into the following subdivisions, in descending order, the lowest four of these having been already adopted in the official description of the country N. of the present map. 4 P. Clays. e. Belt of sandy shale and limestone. d. Clays with thin limestones. c. The Ferruginous Limestone Beds. B. Clays below the Ferruginous Limestone. a. The Hydraulic Limestone Series. The relation of these subdivisions to the Ammonite-zones which form the basis of the palseontological classification of the Lower Lias is as follows : — The zone of Psiloceras planorbis agrees very closely with the lowest subdivision A. The combined zones of Schlotheimia angulata and Coroniceras bucklandi, which are not separately recognisable in this district, fall mainly within the subdivision B. The zone of Arnioceras semicostatum includes the next three subdivisions, C, D and E, here assuming greater importance than in Yorkshire or in Gloucestershire. The remaining zones of Oxynoticeras oxynotum, Echioceras raricostatum, Deroceras armatum, Uptonia jamesoni and Liparoceras capricornus, so far as they may be present, are represented by the subdivision F, but little or no evidence for the zones of Deroceras armatum and Echioceras raricostatum is forthcoming in this district. We will review the general characters of the subdivisions before dealing with the details of their outcrop. 1 By B. Smith, R. L. Sherlock, G. W. Lamplugh, W. Gibson, C. B. Wedd and C. Fox-Strangways. 2 " Geology of the South-west part of Lincolnshire, etc." Mem. Oeol. Surv., 1885, p. 143. 3 " Geology of the Country near Leicester." Mem. Geol. Sure, 1903, p. 29. * "Geology of the Country between Newark and Nottingham." Mem. Geol. Sun., 1908, p. 59. DIVISIONS OF LOWE& LIAS. 23 co The succession is illustrated in the accompanying diagrammatic section, Fig. 3. Hydraulic Limestone Series (a). — These beds follow conform- ably upon the marls and lime- stones of the upper Khaetic, and consist of bluish- grey laminated shales with which are intercalated numerous bands of flaggy argilla- ceous limestone of paler tint. The series is extensively quarried for the manufacture of cement around Barrow-upon-Soar, Barn- stone and wthorpe, the workings affording excellent sections. The outcrop of the series attains an exceptional width of nearly three miles between Crop- well Bishop and Kinoulton, owing partly to slight undulations combined with a very low average dip, and partly to the slope of the ground ; but it contracts greatly along the strike in both directions from this tract, and is not usually more than ^ mile wide. The thickness of the series is about 20 ft. at Barnstone, and slightly less at Barrow-upon-Soar. The valleys of the streams draining the Vale of Bel voir, which are usually shallow and ill-defined, become sharply marked and contracted where they cross these beds. Fossils are not so abundant in the Hydraulic Limestone Series as in the higher zones, but the facilities for collecting afforded by the cement-stone workings are better than in any other part of the Lower Lias of the district. The most characteristic fossils are Psiloceras planorbis, with Psiloceras johnstoni and spines of echinoderms in the upper beds ; a few lamellibranchs ; and the occasional remains of saurians, fish, &c. Clays below the Ferruginous Limestone (b).— Although the zone of Psiloceras planorbis corresponds closely with the Hydraulic Limestone Series, the latter is a lithological rather than a palaeon- tological division, having a somewhat indefinite upper boundary, o > S h X O CO a 3 > w ii W t* tv «T O IS EC CQ < tH J ps "■£ .& m 1 o w o «H ta o W CD to o CO 1 PS o CO -p z s o e a a sT as .o Q I ob M ►5 •<. •4 O' PS « hC5 S5 "§> H a