66 G. W. Lamphigh — The Yorkshire Boulder-clay. 



Balthica is by far the commonest shell, it is not found in the sand- 

 seam ; and on the other hand that, though Astarte compressa is so 

 abundant in the sand, it is rare in the surrounding clay. 



It appears as though the shallow-water and shore-line beds in 

 which Tellina abounded have been more thoroughly obliterated than 

 the deeper-water deposits where Astarte and Dentalinm lived. 



In this new locality, though the shell-bed itself is so limited in 

 extent, it possesses one great advantage over the previously-known 

 exposures, which causes the section to possess a peculiar interest ; for 

 whereas up to this time the shelly patches have always been found 

 either at the foot of the cliff or on the beach, so that nothing could 

 be learnt as to what lay below them, at South Sea' Landing the 

 fossiliferous bed is exhibited in section, and we see the whole of 

 the drift series resting on chalk. 



It has been thought possible in the previous instances that beds 

 similar to the inclusions might occur undisturbed lower in the 

 section ; but in the new locality we see plainly that the stratified 

 sand, silt, and gravel which underlie the. Boulder-clay con- 

 taining the shell-bed have nothing in common with the inclusions, 

 and are quite unfossiliferous. Neither in the stratified bed which 

 overlies the shell-bearing Boulder-clay is there any sign of con- 

 temporaneous fauna, the few worn shell-fragments to be found 

 therein being evidently mere pebbles. 



We have thus now, not only clear proof that the shells did not 

 live where they now occur — a supposition which every feature of the 

 section makes it unnecessary to discuss, — but also evidence to show 

 that they are truly transported boulders, and have not been derived 

 from the destruction of beds which existed in the immediate locality, 

 for we find that no shell-bearing beds occur anywhere in place in 

 these sections. 



Origin of the Shell-bed. 



That the formation of the Boulder-clay containing this shelly sand 

 has been the work of land-ice which filled the basin of the North 

 Sea and encroached upon the land, I have little doubt ; but as to the 

 exact mode in which the sand has been transported I confess I can 

 form no clear conception. 



The work of the ice in this part of the country seems chiefly to have 

 been in the spreading out of successive pavements of clays and 

 gravels, and it is only here and there that we find proof of its 

 erosive influence. Consequently while I can understand well enough 

 how a glacier advancing over a sea-bottom on which lay deposits of 

 sand and clay might churn these up and mix them with its own 

 debris in passing over them, thus manufacturing such a mass as 

 the Basement Clay, I do not see how the sea-bottom could be 

 dragged under the ice for long distances and raised to higher levels. 

 Indeed, I think that all the evidence goes to show that the shelly 

 masses when transported were actually embedded in the ice, and that, 

 their journeying has been exactly analogous to that of the solid 

 boulders. But how they came to be lifted upwards so as to 



