S. V. Wood, j un. — American and British Surf ace-Gcology. 491 
glaciations, and it seems to be still less in Switzerland, because both 
countries are more mountainous tban Canada, and tbe couditions are 
tkerefore in this respect not parallel ; but the similarity is to be dis- 
covered in the circumstance tbat tbe glaciers of the minor glaciation 
were in Britain nonconfluent (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 tnajor glaciation had done. 
Inasmuch as during its greatest extension the ice in Britain did 
not reach much, if any, south of the 52nd parallel, while in Eastem 
North America it reached to the 39tb, it seems clear that the marked 
difierence 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 Eastem North 
America over that in Western, which now obtains, obtained also 
during the Glacial period, as the evidences of glaciation kave not 
on the Pacific coast been detected much if at all south of the 49th 
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. Croll 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 
eflecting a complete diversion front 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 Beindeer 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 Sa 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 
