SS4 Mr Smith on the Changes of the Level of the Sea. 



supposed original rocks is north-west, but in all of them the 

 intervening space is intersected by deep arms of the sea and 

 steep precipitous mountain ranges. It appears to me, therefore; 

 that the till is as ancient as the period of their elevation, and was 

 most probably caused by the violent geological action by which 

 it was accompanied. 



It is, at all events, in Scotland anterior to the marine alluvia 

 which I am describing, and which have been observed reposing 

 upon it in many places. It is proper, however, to observe, that 

 in some instances we find stratified alluvium below the till. I 

 have observed this near Glasgow, and on the west coast of Ire- 

 land ; and Mr Bald, in describing that of the Forth, remarked, 

 that in one case, when it was cut through to the depth of 162 

 feet, the lower bed appeared to have been deposited in water in 

 the most quiescent state, as it was divided into the finest laminae. 

 In neither of these cases were marine remains detected, but Mr 

 Mantell has described an ancient beach as passing under the 

 elephant bed in Sussex, and Sir Philip Egerton found a bed of 

 shells under the ordinary sand diluvium of Cheshire.* These 

 facts do not invalidate the conclusion, that the changes in the 

 level are posterior to the deposition of the till ; they only prove 

 that it has not swept away the whole of the pre-existing alluvia. 

 I have observed the marine beds resting on Till near Glasgow, 

 and in the excavations of the railway from Edinburgh to 

 Newhaven. Mr Thomson has observed it in Dumbarton- 

 shire. -|- At Johnstone, near Paisley, in digging a well, a ma- 

 rine deposit, containing the bones of fishes and sea-fowl, the 

 claws of crabs, sea- weed, and shells, was found to rest upon a 

 bed of it, upwards of 70 feet in thickness. Mr RobberdsJ 

 and Mr Rose || have observed the same order of position in the 

 county of Norfolk. 



We can, therefore, have no hesitation in considering that in 

 these localities changes of level have occurred posterior to the 

 deposition of the diluvial covering, although it is not improba- 

 ble that in some parts of the British islands it may have been 

 lodged on the surface subsequent to the period when the sea 



* Proc. Geol. Soc. vol. ii. p. 190. t Records of General Science, i. 132. 

 + Phil. Mag. Oct. 1827, p. 281. 11 lb. Jan. 1836, p. 34. 



