Keuper Marl Research Articles

Triassic and Pleistocene Surfaces on some Leicestershire Igneous Rocks

The ancient rocks of Leicestershire may be taken to comprise the pre-Cambrian volcanic and sedimentary rocks of Charnwood Forest, and the igneous rocks intrusive into them, viz. the dacite-porphyrites of Bardon Hill, Peldar, and High Sharpley, etc., the granophyric diorites and porphyrites within and south-west of the Forest and in South Leicestershire, and the Mountsorrel granite or granodiorite. There is reason to believe that all except the last are pre-Cambrian in age: for the last a post-Silurian age seems most probable. These ancient rocks are now exposed through the removal of the Keuper Marl, whichhad largely if not completely buried them. In glacial times, however, small areas have been reburied under glacial deposits.

The Age of the Midland Basalts

In the course of work on the Midland Coalfields one of the many problems that have occupied attention has been the question of the age of the basalts associated with the Coal Measures. Extrusive basic igneous rocks that are known to be of Lower Carboniferous age occur at Little Wenlock in Shropshire, in the Bristol district, in North Staffordshire, in Derbyshire, and in Cumberland. Rocks of similar type are present in the Upper Carboniferous of the Midlands, but hitherto no definite evidence of their age has been produced. The distribution of these rocks is shown on the accompanying map (Pl. I). The Butterton and Swynnerton dyke in North Staffordshire and the Grinshill and Acton Reynald dyke in North Shropshire both traverse the Keuper Marl and are therefore definitely post-Triassic. Kinlet.—The Kinlet basalt lies approximately between the Sweet Coal (Yorkian) and Sulphur Coal (Staffordian) Groups of the Wyre Forest Coalfield; that is, in the position of the unconformity or ‘Symon Fault’ in the Coalbrookdale Coalfield. In an old quarry about 300 yards S. 20° W. of Mass House Farm, near Kinlet, the following section is exposed:— Feet. Inches Sandstone, yellowish-buff, flaggy. The lower layers are dark btrn in colour and consist of sand grains in a matrix of decomposed basaltic material with pebbles of basalt and portions of amygdales. 2 0 Coarse grit of small quartz pebbles up

Obituaries

THOMAS OWEN BOSWORTH, who died in London on Jan. 18 last, was born at Spratton, Northamptonshire, on Mar. 28, 1882. He was educated at St. John's College, Cambridge, and was on the staff of the Geological Survey of Scotland in the years 1908 and 1909. The remainder of his life was mainly spent abroad as an oilfield geologist. In this capacity he travelled extensively in America, ranging from Peru to within the Arctic circle. His published works include “The Keuper Marls around Charnwood” (Leicester, 1912), “Geology of the Mid Continent Oilfields, Kansas, Oklahoma, and North Texas” (New York, 1920), “Geology of the Tertiary and Quaternary Periods in the North-West Part of Peru” (London, 1922), and several papers in the Geological Magazine. In the work on Peru, Bos-worth gives a fascinating account of the later geological history of the region, and his description of the present conditions and processes in the desert is full of interest to both geologists and geographers. By his death at the early age of forty-six years, geology has lost a very able investigator.

The Liassic Rocks of We Radstock District (Somerset)

I. Introduction. The Liassic rocks described in this paper are those found within a radius of about 4 miles of Radstoek. The area dealt with is a low plateau, about 400 feet high, capped by Oolites and dissected by a number of rather narrow valleys. The Lias quarries are generally situated just below the plateau-level; the valleys are usually in deep red Keuper Marl, but in some of them the horizontal Mesozoic rocks are seen resting on gently folded Coal Measures, which have long been worked in the neighbourhood. The Liassic rocks of this area have attracted considerable attention, because they are unusually thin, and in the lower part, exceptionally fossiliferous. The Lower Lias (Hettangian, Sinemurian, anjl Lower Charmouthian) is exposed in a great number of small quarries in the neighbourhood, and as each of these shows the entire succession from White Lias to Charmouthian, considerable detail concerning the sequence is available. The peculiarities of the Liassic rocks of the district result from the fact that the area is situated immediately north of the Mendips; it is well known that there was repeated movement along this axis, intermittently from post-Carboniferous times until well into the Mesozoic. The consequences of these movements are seen at Radstock: (i) in the condensed development of certain Liassic zones ; the whole of the Lias thins as it is traced from Gloucestershire southwards to the Mendips, and from Dorset northwards. (ii) in the numerous non-sequences which have resulted mainly from

II. The Geology of a Composite Intrusion at Bennan, South Arran

The Composite Dyke at Bennan, South Arran. There occurs in the extreme south of the island of Arran a composite intrusion composed of three sheets. The prominent cliffs produced by the weathering out of the intrusion have been remarked, in their references to Bennan Head, by most writers on Arran for a century. Inland from the sea the position of the dyke is marked by raised barren ground, for the intrusion is more resistant than the sandstones and marls through which it cuts. It is accurately mapped on the colour-printed geological map of Arran published by the Geological Survey of Great Britain in 1910. The intrusion cuts steeply through the Keuper marls and sandstones (Gregory, page 179), which are gently baked, whilst it is cut in turn by numerous basic dykes which throughout the Western Isles are regarded as being of late Tertiary Age. Since the Mesozoic was a period of volcanic quiescence in Scotland, the dyke is a product of early Tertiary volcanic activity. The two outer sheets are quartz “dolerite” and the central one enclosed between them is quartz porphyry. At its northern termination where the dyke approaches the main road the central sheet pinches out and the two other sheets coalesce into one. The “dolerite” thus forms a sheath enclosing the porphyry. The outer margins of the sheath show chilled edges due to rapid cooling, but the junction between the “dolerite” and the porphyry is ragged, with apophyses of the latter intruded into the former. Fragments of This 250-word extract was created in the absence of an abstract

Petrological notes on the Houston Marl

In the autumn of 1921 my friend, Mr Cadell of Grange, sent me some specimens of Houston Marl, with the request that I would examine them with especial reference to the possibilities of finding some economic use for the rock. The main object he had in view has not been realised, but some facts have been brought to light which seem worthy of record. The following notes are based on specimens from a burn one quarter of a mile west of Ecclesmachan; from West Binney, one and a half miles west of Ecclesmachan; and from a locality, probably near Ecclesmachan, the exact position of which cannot be fixed; others were obtained from the Geological Survey of Scotland, through Mr D. Tait, from two bores near Blackness—those from No. 1 bore came from depths of 221 feet 6 inches and 240 feet, and those from No. 2 bore from 744 feet. The specimens from surface out-crops have naturally been affected by the weather; they break up readily into small angular fragments, and joint planes are often coated with a dark brown film of oxide of iron, with which some manganese is probably associated. One of the specimens from West Binney showed traces of “ ball-jointing,” a common feature of the Keuper marls of the Midland counties of England. With the exception of a reddish-brown marl “ interstratified with green marl ” in the Ecclesmachan burn, all the specimens have a greenish tinge, varying from very dark, in those from the bores,

V.—On two Borings for Water at Hinckley, Leicestershire

Though Hinckley is now possessed of an excellent supply of water brought from the Lower Keuper Sandstone of Snarestone, in North-West Leicestershire, up to 1891 it had an unenviable reputation for abortive water-schemes. Some £20,000 had been spent in considering eighteen different propositions and in carrying out three deep borings within a few miles of the town. During this time six consulting engineers were called in by the local authority. All these schemes failed, not through any lack of water—for this was obtained from the Waterstones of the Lower Keuper in almost unlimited quantity—but because it was found impossible to shut out the chlorides and sulphates from the gypsiferous Keuper Marls through which the borings passed.

IV.—The Keuper Marls around Charnwood. By T. O. Bosworth, B.A., B.Sc., F.G.S. Being the results of researches in Leicestershire, 1904–1911. pp. 1–129, with 47 illustrations. Leicester: published by the Leicester Literary and Philosophical Society. n.d.

An abstract is not available for this content so a preview has been provided. Please use the Get access link above for information on how to access this content.

The Keuper Marls Around Charnwood

Investigation on the Keuper Marls during the past seven years has been the subject of various papers by the author, read before the Leicester Literary & Philosophical Society, the British Association (1907), and finally before the Geological Society (1910). As the complete work is being published in book form, only a brief abstract is given in these pages. The area under consideration—about 300 square miles in extent—is situate on the eastern edge of the central plain of England, and the greater part of it is within from 150 to 350 feet of sea-level. Rising sharply in this plain are the hills of Charnwood, formed of pre-Cambrian rocks, peeping up through the mantle of Keuper Marls, by which they were doubtless once completely covered. The Marls are now found on the flanks of all these hills, and are seen in the quarries at Bardon Hill resting on the old rocks at 810 feet above O.D. and in joint-cracks up to within 32 feet of the summit (912 feet above O.D.), which is the highest point in Charnwood. As has been shown by Prof. W.W. Watts, denudation of the soft Marl cover is gradually revealing the pre-Triassic land-surface almost intact. In this paper are described some of the details of the old rock-surface found beneath Keuper Marl in the quarries. Generally, the quarries have been opened in the tops of the buried or almost buried hills; and as usually the extension of a quarry on each occasion is carried on in the

The Upper Keuper (or Arden) Sandstone Group and Associated Rocks of Warwickshire

I. Introduction The field-work on which this paper is based was mainly carried out between 1895 and 1901, at a time when I lived near Birmingham. It was then suspended, owing to my removal from the district, and until 1911 I was unable to revisit the ground and advance the mapping sufficiently for the presentation of this paper. Even now I have been compelled to curtail considerably my original plan of work, which was to zone the Keuper Marls of Warwickshire from base to summit as far as possible, and, when that was accomplished, to investigate their lithology and fossils with the view of ascertaining their origin and mode of formation. The present paper deals mainly with the stratigraphy, tectonics, and geological relations of a well-marked horizon in the Marls which is usually known as the ‘Upper Keuper Sandstone,’ and further work on the Marls of this area must be left to other workers. II. General Description of the District. The portion of Warwickshire to he described extends from the neighbourhood of Solihull, Knowle, and Barston on the north to Wilmcote and Snitterfield, near Stratford-on-Avon, on the south; and from Tanworth-in-Arden, the Alne Hills, and Wixford on the west to Hatton and Claverdon on the east, an area of about 108 square miles. The Keuper Marls occupy the whole of this district, except where they are overlain in the south by the Rhætic and Lower Lias, and in the north, near Knowle, by an outlier of the same formations. Geologically

I.—On the Evidence for Desert Conditions in the British Trias

A paper by Mr. J. Lomas on “Desert Conditions and the Origin of the British Trias” appeared last year in the Proceedings of the Livepool Geological Society, and was reprinted, with some slight abridgement, in the November and December numbers of this Magazine. Valuable and suggestive as it is, I venture to think that its author, as is not unfrequent with enthusiastic advocates, is attempting to prove too much. I have more than once expressed my belief that the pebble beds of the Bunter, perhaps also its Upper and Lower Sandstones, were deposited on a lowland by mountain-fed rivers, and think it very probable that this lowland, in consequence of its temperature rather extreme, as is the case in Turkestan and parts of Persia; the occasional wind-worn sands being due to the one cause and the angular breccias to the other. But I think the Keuper Marls, on the whole, aqueous rather than æolian in origin, and the Lower Keuper Sandstones, with the Waterstones, indicative of the gradual setting in of inland sea conditions. From time to time, before the salt lake attained its greatest dimensions, the wind might blow the lowland dust into dunes or carry it away from the shore till much of it settled down beneath the water, but I still think that a large part of the material, which now forms the red marl, was brought down as river mud to this magnified Dead Sea, by the streams which had formerly transported sand and pebbles. In regard to this, however, we cannot at present speak dogmatically. More study is needed of the constituents of the Keuper Marl, of fluviatile, lacustrine, and even marine muds, as well as of the lighter æolian deposits, before we can determine what parts wind and water have respectively taken in making this member of the Trias. Here, however, I may remark that neither Professor Watts nor Mr. Walcot Gibson was the first to observe that in the Charnwood Forest region the Keuper fills up hollows in the older rocks.

The Causes of Variegation in Keuper Marls and in other Calcareous Rocks

I t has long been known that the colouring of stratified rocks is chiefly due to the presence of compounds of iron, although the conditions under which deposition of iron has taken place have not been fully determined. The occurrence of red and green masses of rock in juxtaposition, such as is observed at the junction of the Tea-Green and Red Marls of the Keuper, has given rise to speculation regarding the origin of variegation, but no hypothesis affording a satisfactory explanation of the chemical changes which must accompany such phemonena has been hitherto advanced. It is generally taken for granted that the red colour of a variegated rock is determined by the presence of ferric oxide, while the green colour is attributed to iron in the ferrous state; and the suggestion has been made that the condition of the iron in the distinct parts of a variegated rock may, in some cases, be dependent on the relative amount of calcium-carbonate present. As far back as 1868, George Maw called attention to the fact that many noncalcareous rocks are red in colour, and he advanced the opinion that the lighter-coloured bands in variegated rocks have been formed from the red or brown rock by addition of calcareous matter from without. This view, that the green portion has been derived from the red portion, appears to be generally accepted by geologists at the present time; and so it seems desirable to quote at length the concluding paragraph of that section of Maw's

On some Quartzite-Dykes in Mountain-Limestone near Snelston, Derbyshire

I. DESCRIPTION OF THE QUARRY AND THE DYKES. About 3½ miles south-west by south of Ashbourne, near Snelston Common, is an inlier of Mountain-Limestone surrounded by Keuper Marl. According to the Geolo~cal-Survey Map, the outcrop of limestone is roughly elliptical in shape, the major axis extending for a distance of about half a mile in a north-north-easterly direction, and the minor axis in a west-north-westerly direction for about one eighth of a mile. Coekshead Lane, the road from Norbury to Cubley Common, passes over the inlier, which only forms a slight feature in the landscape, at a height of about 600 feet above Ordnance-datum. On a clear day, some of the churches and chimneys of Derby, distant about 11 miles, can be seen from the top of the quarry. The limestone has been quarried on both the north and south sides of Cockshead Lane for about 40 feet below the ground-level, so that the lane passes over a high wall of limestone-beds, which have been left intact between the two quarry-floors. The northern quarry is now disused. It contains lead-and copper-ores, which were worked about 30 years ago. It is outside the area of the main mass of Mountain-Limestone to which the curious lead-mining laws apply, and I was informed that the present owner does not allow the lead-ore to be worked. The quarry south of Cockshead Lane is being worked for roadmetal.The inlier is in the form of a dome or pericline,with its greatest extension

On a Deep Boring at Lyme Regis

I. Introduction During 1901 a boring was made near Lyme Regis in search. of coal, and was carried to the depth of 1300 feet without reaching the base of the Upper Triassic marls. The story of this endeavour to find coal at a place where no geologist would have recommended the attempt, is one which has often been repeated at different places. The undertaking was promoted by a ‘practical man’ who had experience of coal-mining in South Wales, and who had convinced himself that coal was likely to be found at no great depth near Lyme Regis. He obtained permission to bore, and induced a certain number of persons to form a syndicate, for the purpose of making a boring to ascertain the depth at which the expected Coal-Measures were to be found. The results of the boring have a twofold interest: first, to all people in the South-west of England they should be a warning against the folly of expecting to find Coal-Measures at a depth of less than 2000 feet below any part of Western Dorset; secondly, they are of interest to geologists, for the information which is thus afforded as to the great thickness of the Keuper Marls in Devon and Dorset. It was anticipated that coal would be reached at a depth of less than 600 feet, and when this limit was passed without success it was decided to continue the boring to 1200 feet. At this depth it would have been abandoned, had it not

Notes on the Genus Lichas

I. Introductory. During 1901 a boring was made near Lyme Regis in search. of coal, and was carried to the depth of 1300 feet without reaching the base of the Upper Triassic marls. The story of this endeavour to find coal at a place where no geologist would have recommended the attempt, is one which has often been repeated at different places. The undertaking was promoted by a ‘practical man’ who had experience of coal-mining in South Wales, and who had convinced himself that coal was likely to be found at no great depth near Lyme Regis. He obtained permission to bore, and induced a certain number of persons to form a syndicate, for the purpose of making a boring to ascertain the depth at which the expected Coal-Measures were to be found. The results of the boring have a twofold interest: first, to all people in the South-west of England they should be a warning against the folly of expecting to find Coal-Measures at a depth of less than 2000 feet below any part of Western Dorset; secondly, they are of interest to geologists, for the information which is thus afforded as to the great thickness of the Keuper Marls in Devon and Dorset. It was anticipated that coal would be reached at a depth of less than 600 feet, and when this limit was passed without success it was decided to continue the boring to 1200 feet. At this depth it would have been abandoned, had it not

V.—Another Section of Keuper Marls at Great Crosby, Lancashire

In 1884 I described in the GeologicalMagazine a section of Keuper Marls exposed by the excavation of the Boulder-clay at Moorhey, Great Crosby. This was our first knowledge of their existence in the neighbourhood, the whole area being covered with a thick mantle of Boulder-clay excepting where the Lower Keuper Sandstone comes to the surface in the villages of Great and Little Crosby.

II.—On a Recent Boring in the Trias at Stratford-on-Avon

The question of the water supply of the town of Stratford-on-Avon has for years past presented many difficulties. The town is situated on the uppermost beds of the Upper Keuper Marls, and the water derived from the wells sunk in these gypseous marls, or from the alluvial gravel of the river valley, contains an amount of solids equal to about 170 grains per gallon, of which about 125 grains consist of calcium sulphate. Up to a very few years ago this intensely hard water was alone available for domestic and manufacturing purposes, but the main supply of the town is now derived from catchment basins and reservoirs at Snitterfield on the adjoining hills about four miles north of Stratford. In years of average rainfall a fair supply of moderately soft water is obtained from this source, but it is one which, as regards organic impurity, bears unmistakable signs of its surface origin, and during dry seasons the town supply has to be supplemented with the hard well-water I have already referred to.

Discovery of Mammalian Remains in the Old River-gravels of the Derwent near Derby.— Part II.

The deposits in and beneath which the mammalian remains were found occur on the inside edge of a gravel–terrace which covers a large area on the right side of the Derwent Valley below Derby. Its south–western boundary is more or less obscured by a variable thickness of unstratified, yellow, sandy clay containing pebbles. Masses of this pebbly deposit frequently penetrate 6 or 8 feet into the gravel, much as does the ‘trail’ of Southern England. At its inner edge the gravel terminates against rising ground, composed of Keuper Marl capped in places by Boulder Clay. The line of junction between the gravel and the Keuper commences on the south side of the breach made in the Derwent Valley escarpment by the Kedleston Brook. From here it skirts the lower portion of the Royal Infirmary grounds, crosses the railway near Osmaston Road, passes a few yards to the south–west of the section at Allenton, and then skirts the base of Chellaston Hill until the river–escarpment of the Trent, a mile north of Aston–on–Trent, is reached. Its north–eastern boundary is a continuous and steep escarpment about 18 feet above the modern alluvial plain of the Derwent. This escarpment, starting near the Kedleston Brook breach, passes through the Midland Railway–station, and keeping on the north side of the London road, passes through Alvaston, Elvaston, and Aston, when it joins the corresponding escarpment of the Trent Valley. This portion of the ground I have contoured, so as to show the exact relationship between the

A Comparison of the Red Rocks of the South Devon Coast with those of the Midland and Western Counties

In September last I found it possible to carry out a long-standing engagement with the Rev. Dr. Irving to visit South Devon in his company, and to form an opinion upon his views regarding the age and succession of the great series of red rocks which are exposed to view in such magnificent sections along the coast to the east and west of the estuary of the River Exe. On reading Dr. Irving's paper, published in this Journal in 1888, it appeared to me that he had gone very far towards establishing his proposition that the brecciated beds forming the base of the whole series, and resting discordantly on the Devonian rocks, were really the representatives of the Lower Permian breccias of the Midland and Western counties, but I was little prepared for the—I might almost say—overwhelming evidence that such is the case upon an examination of the coast sections extending from Oddicombe Bay to and beyond Teignmouth and Dawlish. Having examined these basement-beds of the series, we continued our survey of the coast and inland sections of the succeeding strata eastwards to Sidmouth—terminating with the Keuper marls underlying the Cretaceous beds which form the cap of Salcombe Hill, and which break off in a lofty and precipitous cliff seawards; so that the whole structure of the ridge is laid open from the summit to the water's edge. The result of this reconnaissance has been to enable me to confirm in all the main points Dr. Irving's view, and to

Geology of the Country around Liverpool

IN this work Mr. Morton has entirely re-written the “Geology of the Liverpool District,” first published in 1863, by the light of the various discoveries made since that time, and especially of the Geological Survey maps and memoirs. He has succeeded in making a compact and well-printed hand-book, which will be of great service to the students of the local geology. The area described extends to about 20 miles from Liverpool on every side, excepting the sea on the west. The strata which he describes range from the Upper Silurians of the Vale of Clwyd through the Carboniferous, Permian, and Triassic rocks, down to the recent alluvia. To a geologist the chapter relating to the Carboniferous rocks of North Flintshire and the Vale of Clwyd will be of great interest, as it shows the thinning off of the strata as they approach the ancient Carboniferous land of North Wales. The Carboniferous Limestone, over 3000 feet thick in North Lancashire, is reduced to 1700 feet in North Flint and the Vale of Clwyd; while the Yoredales and Millstone Grits, over 9000 feet thick between Clitheroe and Burnley, are represented by the Cefn-y-Fedw Sandstone, 370 feet. The Lower and Middle Coal-measures, too, of South-West Lancashire, 31 8o feet thick, have dwindled down to no more than 1ooo feet as they approached the Welsh Silurian Hills. It is therefore obvious that the Snowdonian area was dry land while the Carboniferous sea occupied the areas of Lancashire, Derbyshire, and Cheshire, and that it also overlooked the forest-covered morasses, now represented by the coal-seams. of the same region in the Upper Carboniferous age. In the table of the rocks (p. 6) Mr. Morton gives 300 feet as the thickness of the Millstone Grit in South-West Lancashire. It is probably much more than this, and not much less than 2000 feet. Mr. Morton also, we may remark, understates the thickness of the Keuper Marls, which he puts down at 400 feet (p. 75). In the Lancashire and Cheshire plain it is 700 + feet, and is estimated by Prof. Hull at 3000 feet. Geology of the Country around Liverpool. By G. H. Morton Second Edition. (London: Philip and Son, 1891.)