T. F. Jamleson — Oscillation of Land in Glacial Period. 457 



P.S. — I would add that the term " Pre-glacial," though sometimes 

 a convenient word to use, is very objectionable in any system of 

 classification. The " Pre-glacial " beds on the Norfolk coast are 

 stratigraphically connected with the Pliocene strata, and although 

 they present some palasontological features that serve to connect the 

 Crag deposits (Pliocene) with the Glacial Drift (Pleistocene), I agree 

 with my colleague, Mr. Eeid, in grouping the Norfolk Pre-glacial 

 or Forest Bed Series with the Pliocene rather than with the Pleisto- 

 cene deposits.^ 



\1. — On the Cause of the Depression and Ee-elevation of the 

 Land during the Glacial Period. 



By Thomas F. Jamieson, F.G.S. 



[Concluded from p. 407.) 



Application of the Hypothesis — England. 



In England the ice seems to have been heaviest in Wales and the 

 N.W., and lightest on the East and S.E., where it appears to have 

 thinned off altogether, and the evidence of depression corresponds 

 with this. If we draw a line from Dover to Angiesea, we find proof 

 of great submergence in Wales, decreasing to zero as we approach 

 the English Channel. And Prof. Hughes of Cambridge, in a recent 

 paper "On the Evidence of the Later Movements of Elevation and 

 Depression in the British Isles," read before the Victoria Institute, 

 says : " As we trace these movements north to the borders of the 

 mountains, we find evidence of greater sinking and greater elevation." 

 . . . . " Along the mountain chains the movements were alwaj's 

 greater." Then as to the order in which the movements took place, 

 we find tlie following statements : — " This point is clear that after 

 glacial times the land went down below the sea, and then the ice 

 was lifted and melted off. After that the land began to rise." In 

 like manner Professor Eamsay writes : ' Of this I am certain that 

 probably during and certainly after the largest extension of glacier- 

 ice, the land underwent a process of submersion " (Phys. Geol. of 

 Gt. Britain, 5th ed. p. 411). " After what seems to have been a long 

 period of partial submergence, the country gradually rose again " 

 {ih. p. 419). 



It is impossible not to see how closely this order of events 

 corresponds with the hypothesis I am advocating, and this same 

 order seems to have been the rule in all glaciated regions. The 

 land is first heavily loaded with ice, then it goes down and the ice 

 clears off, after which the land comes up again. The chief sub- 

 mergence or depression seems to have always followed hard upon 

 the great glaciation of the country, and the disappearance of the ice 

 which then took place is followed by the land rising again. The 

 conclusion seems obvious. 



li\ Ireland the Eev. Maxwell Close and Professor Hull require 



^ Mr. Eeid's Memoir on the Geology of the Country around Cromer (in the press) 

 ■will give full particulars of these deposits. See also Prof. W. Boyd Dawkins, 

 Address to Department of Anthropology, Brit. Assoc. 1882. 



