Chalky Boulder Clay Research Articles

The Boulder-Clays of Lincolnshire. Their Geographical Range and Relative Age

In section 3, we came to the conclusion that the brown and mottled clays of the Fen-border and the Ancholme valley were newer than the Chalky Boulder-clay of those districts; further that there was a decided break and an apparent unconformity between the two groups. In the last section I denied the existence of any break in the Brown-clay series of East Lincolnshire ( i.e. the Purple and Hessle Clays), and showed that Mr. Lamplugh holds the same opinion with regard to the continuity of this group along the Holderness coast. It seems therefore only reasonable to conclude in the first place that the Glacial beds found on the west and on the east of the Lincolnshire Wolds do not form parallel series. If the Chalky Boulder-clay and the Purple Boulder-clay were correlatives, we should be confronted with the anomaly of a continuous succession existing on one side of the Wolds, while there is a discontinuous succession on the other. Assuming that they are not parallel series, and also supposing for the moment that the brown clays on either side of the dividing ridge in Lincolnshire are complete correlatives, then it is the Chalky Clay which is unrepresented on the eastern side. Now in East Lincolnshire the base cannot be seen; but in Yorkshire there is a grey and chalky Basement-clay (beneath the Purple-clay) which was originally regarded by Messrs. Wood and Rome as the equivalent of the Upper Glacial-clay of East Anglia. Moreover we have Mr. Lamplugh's testimony as to

II.—On the Age of the Mammalian Rootlet-bed at Kessingland

In two papers, by Messrs. S. V. Wood, jun., and F. W. Harmer, recently read, before the Geological Society,—alluded to by Mr. Belt, in the GeologicalMagazine for April last,—this Rootlet-bed at Kessingland has been referred to, and described as an interglacial shallow valley deposit; of an age posterior to the Contorted Drift or Lower Boulder-clay, lying in a trough excavated out of the Chillesford Clay. To make their description more intelligible, the authors (Messrs. Wood and Harmer) subjoin a sketch-map—in their combined, paper “Observations on the Later Tertiary Geology of East Anglia,” read November 8th, 1876—and indicate by a broken line the connexion of this trough with the existing (!) valley systems of the rivers Waveney and Yare—which are here mainly cut out of the Chalky Boulder-clay and Middle Glacial Sands—thus apparently assuming that, before the Middle Glacial Sands and Chalky Boulder-clay were deposited, there were valley systems occupying much the same positions in this immediate locality as there are now, with the addition of the supposed continuation of the interglacial valley of the Waveney in a south-easterly direction to Pakefield and Kessingland.

On the Relation of the Boulder-clay, without Chalk, of the North of England to the Great Chalky Boulder-clay of the South

I n a paper read before this Society by myself and the Rev. J. L. Rome, F.G.S., and published in the Journal, we described the Glacial clay of the Yorkshire coast as consisting of two main parts. Of these, the lower, distinguished both in our sections and in the vertical section accompanying the present paper (see Pl. VII.) by the letter a , presents characters identical in all respects with the ordinary Boulder-clay, with chalk as its prevailing constituent, which forms the uppermost member of the Glacial series of the east and east centre of England; while the upper ( c ) is a purple clay, in which chalk is only a subordinate constituent, even in the lower part, and which, gradually losing its chalk upwards, is in the upper part entirely destitute of it. We also endeavoured to show that, north of Flamborough Head, the whole of the clay, (which is destitute of chalk), belonged to this upper part only—and that, though lying at the foot of the northern escarpment of the chalk, as well as enveloping both the escarpment and the Wold, this clay, thus destitute of chalk, was not deposited until, by the complete submergence of the Wold, all source of chalk débris had been removed. We also suggested that the absence of any clay with chalk débris in these parts was due to their having been occupied by ice during the time that the clay containing that material was accumulated, and to this ice not having been removed until the