﻿490 S. V. Woodjjim. — A?nerican and British Surface- Geology. 



generally of conditions as frigid as those which prevailed during the 

 first giaciation. On the other hand, if there never was anything 

 more than such a limited depression of the St. Lawrence basin as 

 sufficed to bring the Atlantic waters over those parts which are 

 covered by the Leda, Champlain, and other marine clays of the coast 

 districts (and I fail to see how there could have been more), we 

 should not find this explanation of difference in level available as 

 an explanation, but be driven to infer that the giaciation to which 

 the beds overlying the forest- surface were due was a minor one ; so 

 that the ice did not reach to its former position, but damming up the 

 lower valley of the St. Lawrence (which lies in several degrees higher 

 latitude than Ohio), it filled the lake-basin with the waters produced 

 by its dissolution, over which drifted the ice from whose droppings, 

 and from the mud and gravel taken up by currents from the glacier 

 discharge, these beds appear by Prof. Newberry's description to be 

 made up — beds which possess very much the physical character of 

 the Contorted Drift of Cromer, without its included marl masses, as 

 well as of the purple clay of the district near Flamborough Head 

 which is shown in the sections accompanying the sequel of this 

 paper imder the letter d. 



3. The beds thus overlying the forest-surface in Ohio consist, 

 according to the Professor, of clays, sands, and gravels of various 

 kinds, sometimes containing boulders as well as having boulders 

 extensively scattered over them. These beds, to which I have already 

 referred under the symbol 3a, he considers were deposited by the 

 lake- waters while the Canadian highlands were occupied by glacier- 

 ice, from which bergs breaking off drifted over the lake-basin and 

 scattered blocks. 



Looking at the general group of facts affecting the American 

 region as described by Prof. Newberry, and at the general facts with 

 which a long study of the English beds have made me familiar, I 

 strongly incline to the belief that both in America and in Europe 

 there have been two glaciations only ; one, the greater, during which 

 the beds that I term glacial were accumulated, and when Britain 

 underwent its general submergence; and the other, the less, which 

 was subsequent to the general emergence of this country, but oc- 

 curred while the South of England was still partially submerged, and 

 the North of England and South of Scotland had undergone partial 

 resubmergence, and during which the older part of the beds that I 

 term post-Glacial were accumulated. I think that if we take into 

 consideration the greater height of the glacier generating land in 

 Britain over that in Canada, this minor giaciation bears the same 

 proportion to the major in both countries ; for the Canadian high- 

 lands forming the northern lip of the St. Lawrence basin, and on 

 which, according to Prof. Newberry, the ice terminated and sent off 

 its bergs during the accumulation of the beds 3a, lie between 

 latitude 45° and 50°, which is at least 5° of latitude short of that 

 to which the grooved rock-surface of Ohio shows the glacier-ice 

 giving rise to the Erie q\kj had reached. In Britain there is not 

 this difference in latitude between the limits of the major and minor 



