Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/540

416 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 23, opinion glaciated up hill either by a great flow of land-ice or by floating ice. The mode of striation of the stones which have been taken off the fields, or dug out of one or both Boulder-clays, and heaped on the road-side between Lancaster and Carnforth, would seem to point to the action of floating ice. The striations very frequently occur on more than one side, often on nearly opposite sides, and sometimes all round the stone, in a manner indicating that the stone was not only turned over during the process, but twisted round horizontally.

Beyond Carnforth railway-station a section on of reddish Boulder-clay full of stones lying at all angles has been exposed in a cutting. South of the station the cutting reveals the most extensive section of sand and gravel I have yet seen. It reaches a thickness of nearly 100 feet, and is about a quarter of a mile in length. It is so extremely varied as almost to defy description. For a considerable distance there are few or no large stones, the deposit consisting of alternating beds of coarse and fine sand and coarse and fine gravel, obliquely laminated and false-bedded on an extensive scale. There are several interpolated beds or masses of unstratified gravel, and towards the bottom a thick bed of laminated loam. The stones are not striated, with the exception of a very few of the largest, which are scratched all round. Some of the layers of sand and pebbles are as hard as Eagberg rockery. Further south the gravel contains a number of very large stones striated in various directions; it then becomes one mass of stones lying at all angles, and as firmly compacted as the stones of the Lower Boulder-clay; it afterwards graduates into a regularly stratified and false-bedded gravel, which further on contains a great number of large boulders. The beds of the Carnforth section are apparently contorted to a certain extent, but not nearly so much so as in the sections near Ulverstone. The stones are nearly all limestone.

a. Derivation of Limestone Boulders.—Supposing the smaller stones which compose the false-bedded part of the gravel to have been amassed by currents, the large boulders could not have been moved to their present positions independently of ice-action. But a study of the physical geography of the district will convince one that when the land was submerged to the depth indicated by the sand and gravel, the upper parts only of the neighbouring limestone hills or peninsulas could have remained above water. Under such conditions land-ice could not have furnished the great bulk of the boulders included in the Carnforth gravels; and the rounded form of these boulders would seem to point to their having been subjected to sea-coast action previously to their transportation. We are thus led to regard coast-ice as the agency by which they were moved; and we need not travel far to find forms of ground and situations from which the boulders may readily have been launched. The face of Warton Hill, nearly opposite Carnforth, presents a series of platforms and cliffs with scattered blocks and fragments; but it was while walking from Warton to Yealand that I was the most impressed with what appeared to be old sea-beaches covered with more or less