﻿540 8. V. Wood,jun. — American and British Surface- Geology. 



ance would have caused, I conceive, the ice to' seek a new direction, 

 the result of which was that its main flow deflected more directly 

 southwards from the Pennine Hills, and formed the large glacier sheet 

 to which the Middle Glacial sands and the chalky portion of the 

 Upper Glacial clay owe their origin, and of which the motion was 

 partly out through the Humber gorge, but principally southwards 

 over Lincolnshire. 



Since thus the earliest deposits of the Glacial period in Britain 

 belong to that part of it during which the ice was beginning to 

 accumulate and during which it was extending, but had not reached 

 its culmination; while according to Prof. Newberry the Erie clay 

 belongs to that part of it during which it was receding, we can 

 hardly suggest any parallelism in time between this clay and the 

 English Lower Glacial beds, unless that part of the period which 

 followed the elevation of the latter and the excavation of the 

 troughs through them waS accompanied by a general recession of 

 the ice and amelioration of climate, as to which there does not 

 appear at present to be any reliable evidence. On the whole, 

 therefore, it seems to me most probable that none of the American 

 beds, so far as they have yet been described, are quite so old as the 

 Lower Glacial series of England ; but that the oldest of them 

 represent the period of recession from greatest ice extension under 

 which the principal glacial formation of Britain, the Upper Glacial, 

 was accumulated. 



As, however, the object of the present attempt at synchronism is 

 tentative only, I have thought it most convenient to place the oldest 

 described formations of either country side by side, as the clearer 

 way of presenting the subject for the consideration of geologists, 

 and therefore in pursuing that course we get next : 



England. 



St. Laweence Basin. 



The Middle Glacial sand and gravel. 



The Upper Glacial beginning with the Chalky 

 clay of East Anglia, succeeding which comes the 

 Purple clay of Holderness, and such of the clay 

 of the North of England as is not of Hessle age, 

 and terminating with the Moel Tryfaen and Lan- 

 cashire high-level sands with marine moUusca. 



The Forest surface and asso- 

 ciated beds (No. 2), which rest 

 on the Erie clay. 



The beds 3a of Ohio and part 

 of the marine clays of the 

 Lower St. Lawrence and At- 

 lantic coasts. 



If, as already suggested, there was no general recession of the ice 

 and amelioration of climate after the formation of the Lower Glacial 

 series of England, and that therefore the Erie clay and Eskers of 

 the Ohio water-parting more probably represent the Upper Glacial 

 of England, then the beds of the St. Lawrence basin which are 

 above placed beside the Middle and Upper Glacial would, I conceive, 

 belong to that period which we have been accustomed in England to 

 call post-Glacial, and during which a minor glaciation, I consider, 

 occurred ; and I think that this pushing forward of the American 

 beds in the synchronism will eventually be found to accord best 

 with the entire group of facts. 



