Midland Naturalist/Volume 01/A Scheme for the Examination of the Glacial Deposits of the Midland Counties of England
A Scheme for the Examination of the Glacial Deposits of the Midland Counties of England.
By Wm. Jerome Harrison, F.G.S.
Curator of the Town Museum, Leicester.
One of the great advantages which it was hoped would result from the formation of the Midland Union of Scientific Societies, was the opportunity which it would offer to distant workers to become acquainted with one another, with a view to combined work upon the many scientific problems which our district offers to us for solution.
At the Annual Meeting of the Union, at Birmingham, on May 28th, I ventured to suggest the Glacial Deposits of the Midlands as a subject peculiarly fitted for our joint efforts, and as this idea was favourably received both at the time and since, I now venture to offer a few suggestions as to the way in which we should begin work.
I.—The Workers.—No Society can plead an absence of material on which to work, The stratified rocks which constitute what we term the solid geology of our country run in tolerably definite bunts, but the glacial drift is scattered irregularly all over the face of the country, and is with us everywhere. Each Society then should appoint one of its members who should act as secretary or record keeper for the particular study we propose to attempt. The other members who are willing to aid actively in the task should give in their names to him, and he should summon meetings of such members at frequent intervals.
A chief duty of the record secretary would be to keep a large observation book, in which to enter all notes and discoveries. If this book contained plenty of guards such members as preferred it might write out the results of their own work, which could then be pasted in the book.
As it would be absolutely necessary to gain personal experience, it would probably be easy to arrange for joint meetings of all who take an active interest in this work in the various districts in them. The typical deposits of the east and west coasts and of Scotland would also be visited and examined.
II.—The Work.—In the first place it would be necessary for each worker, or at all events each Society, to obtain the Ordnance Maps, both plain and geologically coloured, of their neighbourhood.
Upon the plain maps they should distinguish by dots and numbers the precise position of every gravel pit, brick pit, &c., where the surface deposits are well exposed, Lach at these sections should then he visited. in turn and carefully examined. Each should be measured, and a plan and section—no matter how rough, if fairly accurate—drawn to scale; if a water-colour sketch could be made of the principal face so much the better. In as many cases as possible an idea of the height of each point above the sea level should be obtained either by aneroid, levelling, or computation, The dip, if any, of the layers must be noted, false-bedding looked out for, and especially in the clayey deposits any indications of bedding remarked. Specimens from each point must be collected. If in wooden boxes about 6in. by 4in. an average specimen of each deposit could he secured, it would be of service in comparing with other localities. The stones must be carefully examined for striations, and so also the rock surfaces below when exposed. If 100 stones are collected at random from any pit they should then be sorted according to their composition, and the proportions stated. Specimens of every variety must of course be secured for reference. Fossils must be carefully looked for. So far as I know, not one shell has yet turned up in the drift deposits of the midlands proper. Entire and large shells must not be hoped for, the smallest fragments will be acceptable, and the sand must be washed and examined microscopically for foraminifera, &c.
The large boulders will almost force themselves upon our attention. Good specimens of each measuring not less than 4in. by 8in. must be obtained, and every possible fact recorded about them. Much information may often be got from rustics and dwellers in the neighbourhood generally, and the ideas so elicited are often of the most racy description.
When an examination of the principal open sections has been completed in this way we shall be beginning to obtain some familiarity with our task, and must endeavour to connect our observations so as to make complete maps of the surface deposits, to connect, that is to say, the various exposures so as to show what deposits are present under grass-covered fields or wheat crops as well as in the gravel pits and brick pits which we can so easily examine. This is a point, however, which we can consider further on, only remembering in the meantime to make as many notes about water-supply and well sections as we can, It will be necessary to endeavour to identify the rocks of which boulders are composed so as to determine the direction in which the ice-sheet has travelled. For this purpose typical collections of Welsh rocks, of those of the Lake district, and of Charnwood Forest will be most useful. I shall be glad to forward to any one who is in want of them for this purpose a small collection of typical Charnwood specimens, and doubtless dwellers near other regions of hard and old rocks would also help in this way.
In a separate note book enter at the time as many particular as possible; omit nothing however insignificant, and let each point be visited more than once, and by different workers if possible. It will be found useful to have a small number book, containing sheets of numbers, say from 1 to 1,000, gummed and perforated, When a specimen of a boulder, &c., is obtained, let a number be at once gummed on it, whilst in the note book the same number is written down with full description of locality, I have found this the beat of many plans,
The apparatus required in addition to a map is not much. A geological hammer with a square head and belt with flap to carry it in; small compass, a little acid bottle to test for carbonate of lime, a good satchel or stout gamekeeper's bag, a clinometer, a pocket lens; all these are useful, but I have known a working man with a coal-pick do excellent work, It is a great thing to walk much, to get a thorough geographical idea of the tract of country you ave about to examine. Suppose at the meeting of your "committee on the drift deposits" you with a friend have undertaken the examination of a district including, say ten square miles. Then the best thing to do is to learn this little region thoroughly, to master the course of every brook and streamlet, the position of every house and hedgerow. The number of new facts that are sure to turn up will surprise you.
A complete list of what has already been written upon the drift would more than fill one number of this magazine. "The Great Ice Age," by Mr. Jas. Geikie, (2nd edition, 24s., Daldy, Isbister, and Co.,) is an excellent book. Mr. Searles V. Wood, jun., is another high authority on the subject, to whom I am personally indebted for much kind advice. Unfortunately Mr. Wood's papers are chiefly in the "Journal of the Geological Society" or in the "Geological Magazine," but if may safely be said that no one has done more remarkable and original work in connection with the glacial deposits (chiefly of the eastern counties) than Mr. Wood, In "Geological Survey Memoirs," lately published by Mr. de Rance ("Superficial Geology of S.-W. Lancashire," 17s.) and by Mr. S. B. J. Skertchley (the "Fen-Land," 40s.) we get, of course, most reliable and interesting information, but the price of these works is to individuals almost prohibitory. Such works, however, may well be aided to the libraries of all our societies. I will endeavour to review these two books in our next (October) number. In H. B. Woodward's "Geology of England and Wales" (Longmans, 14s.) there is also a good and full resumé.
No very special training is needed on the part of those who are willing to lend a helping hand. For instance, we want to know how far the chalky boulder clay of the eastern counties extends to the west and south, and also the relations to it of certain beds of flinty gravel and sand. Now everybody knows the appearances of a lump of chalk and a piece of flint, and we ought to be able to fix the westward extension of these beds to a certainty. I have never seen the clay full of bits of chalk in size from a pin's head upwards, at any point west of Charnwood Forest, but then I have not enjoyed many opportunities of examining the drift of Staffordshire, Warwickshire, &c. The flinty gravel appears to stretch further west, but what is its limit in this direction? Again, in the midland district we hold the key to the correlation of the deposits of the cast and west coasts. It is now thought that the glacial deposits of Lancashire and Cheshire are of a later date than the "mid-glacial sands" and chalky clays of the east coast. We must endeavour to track each set of deposits as far inland as possible, and observe their relative behaviour.
With this branch of geological study is bound up the question of the origin of man. If in the Victoria Cave, near Settle, clear evidence is obtainable of pre-glacial or inter-glacial man, why should not other evidence of his presence in the centre and north of England be found?
Then in each midland county if some half-dozen workers will but band themselves together for the prosecution of this study, I see no reason why valuable results should not be attained at an early date, and the exhibition of specimens. illustrative of the glacial deposits of the Midlands, might be made a special feature of the Annual Meeting of the Union at Leicester, in 1879.
If any scheme of the kind hinted at above can be set on foot, I would suggest that the various record keepers meet at given centres, say at first monthly. They should appoint one of their number as a general secretary or reporter, and notices of the work done should appear from time to time in the pages of the "Midland Naturalist."
Finally the three questions upon which it seems necessary to fix our attention are:—
This work was published before January 1, 1931, and is in the public domain worldwide because the author died at least 100 years ago.
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