﻿S. V. Wood Jim. — American and British Surface- Geology. 491 



glaciations, and it seems to be still less in Switzerland, because both 

 countries are more mountainous than Canada, and the conditions are 

 therefore in this respect not parallel; but the similarity is to be dis- 

 covered in the circumstance that the glaciers of the minor glaciation 

 were in Britain nonconiiuent (to any great degree at least), while 

 in America the confluent sheet which they formed was arrested on 

 the Canadian highlands instead of reaching to the centre of Ohio, as 

 the confluent sheet of the major glaciation had done. 



Inasmuch as during its greatest extension the ice in Britain did 

 not reach much, if any, south of the o2nd parallel, while in Eastern 

 North America it reached to the 39tb, it seems clear that the marked 

 difference in climate between the two regions which now exists, and 

 is due to the influence of the Gulf Stream and the action of the 

 prevalent winds, existed in a similar degree during the major glacia- 

 tion ; and we are assured by American geologists that in a similar 

 way the existing preponderance of winter cold in Eastern North 

 America over that in Western, which now obtains, obtained also 

 during the Glacial period, as the evidences of glaciation have not 

 on the Pacific coast been detected much if at all south of the 4:9th 

 parallel. These appear to me to be very pregnant facts indicative 

 equally of the cosmic origin of the Glacial period, and of the 

 inapplicability of the Excentricity theory of Dr. CroU to its explana- 

 tion ; because, by the express statements of its author, the influence 

 of excentricity would be inoperative on climate were it not for its 

 effecting a complete diversion from Western Europe of the Gulf 

 Stream, and its similar operation upon the great currents of the 

 Pacific and other oceans, as well as the prevalent winds. 



An identity of character between the vegetation which intervenes 

 between the Erie clay surface and the beds 3a, and that now grow- 

 ing in the same region, would, if free from question, be of great im- 

 portance, because so much uncertainty attaches to the evidence 

 afforded by mammalian remains upon the question of climate ; some 

 geologists contending that we are entitled to infer from the presence 

 of certain of these mammalia, especially the Hippopotamus, a period 

 of warm or at least temperate climate; while others insist that 

 mammalia adapt themselves so easily to all climates that they furnish 

 no reliable evidence upon the question ; and they endeavour to get 

 over the difficulty of the Hippopotamus inhabiting a country whose 

 rivers would have been thickly frozen over during winter, under 

 conditions of climate much short of glacial, by attributing to this 

 animal migratory habits like those of the Eeindeer and Musk Ox, 

 notwithstanding that in its living state it, and indeed, I believe, all 

 Pachydermata, show, as far as known, no migratory disposition at all. 

 In the case of a flora, however, to a great extent identical with one 

 still growing on the same region, no such uncertainty could, I think, 

 arise ; and if, therefore, in the interval between the Erie clay and 

 the beds 3a we got such a flora, we could hardly deny the interven- 

 tion of a temperate climate ; and were such an established fact in 

 American geology, it would furnish a strong support to the case of 

 a similar interlude between those two glaciations of major and minor 



