III.—On Phenomena connected with Denudation, observed in the so-called Coprolite Pits near Haslingfield, Cambridgeshire

Extract

The upper portion of the sections in these pits usually exhibits from a foot to a foot and a half of soil, which I call, after Mr. Trimmer, “Warp.” In this district it is unusually full of land-shells of recent species. Nevertheless, the assemblage is not exactly what one meets with living on the spot. The most common Helix of the warp is H. arbustorum. This species occurs alive in the neighbourhood, but it can scarcely be called common. Helix nemoralis is common in the warp and also alive. Helix aspersa is by no means common in the warp, but it is common alive. Cyclostoma elegans is very common in the warp, but I have not seen it alive in this neighbourhood. It is exceedingly likely that drainage and cultivation may have been sufficient to have wrought these changes. At the base of the warp I have found an oyster-shell, which looks as if it had been broken at the edge to get it open.