Boulder- Clay. 393 



<r 



of one end of the cliff, is overlaid by sand and gravel, 

 which again is overlaid by lenticular patches of Till, 

 covered by higher gravels, on which, in a hollow, there 

 occur clays with Paludinas deposited in an old fresh- 

 water pool. The same kinds of sections, with variations, 

 are found all the way from Hornsea to Withernsea and 

 Spurn Point, and here and there many large boulders 

 of granite, Carboniferous and Lias Limestones, Sand- 

 stones with Stigmarias, &c., lie on the shore, bearing 

 witness to the recession of the cliff, which is fast 

 wearing away under the united influence of landslips, 

 and the action of breakers and tides on the fallen masses 

 of clay. Nor do the remains of sea-shells cease, for at 

 Out Newton, by the shore, the base of the cliff, in which 

 frequent landslips occur, consists of stiff blue Till with 

 erratic blocks and many fragmentary shells, overlaid by 

 clay with smaller stones, on which lies well-stratified 

 warp clay, surmounted by beds of sea-sand and gravel, 

 which again is overlaid by red Till with scratched 

 stones. On the shore of the Humber, also, when exca- 

 vations were in progress connected with the building 

 of a fort, beds of sand, gravel, and warp were exposed, 

 containing sea-shells intensely contorted, as if the strata 

 had been subjected to strong lateral pressure. 



Between the Humber and the Wash I have no per- 

 sonal knowledge of the coast sections, which are of the 

 same general nature as those of Holderness. South and 

 south-east of the Wash, as far as the neighbourhood of 

 the Thames, much has been written about glacial 

 detritus, with the details of which I will not now 

 meddle. It is enough to state that by Mr. Searles 

 Wood, junr. and Mr. F. W. Harmer, they have been 

 divided into Lower and Upper Boulder-clays, between 

 which there are beds of sand and gravel, often contorted, 



