98 
ORIGIN OF LIFE IN AMERICA 
south. If such an event had happened we should not have had 
such a large percentage of peculiar forms of animal life in 
Alaska, and more southern forms ought to have found their 
way there, such as the American deer and many others. 
It would seem, therefore, as if both the Atlantic and the 
Pacific Ocean became closed in the north simultaneously and 
remained so for a considerable time (Fig. 7). The southern 
shores of both the great land bridges were then under the, direct 
influence of warm ocean currents resulting in favourable con¬ 
ditions for the growth of vegetation and the food supply 
for large mammals. The northern shores of the land 
bridges, on the other hand, were in immediate contact 
with a closed Arctic Ocean, whose waters would naturally 
have remained frozen for the greater part of the year. 
During winter the snowfall all round the northern Atlantic 
and northern Pacific Oceans was probably considerable. 
The land being, moreover, at a higher level, this would 
have resulted in the production of local glaciers. Marine 
transgressions from the Arctic Ocean then seem to have 
taken place across northern Russia, as I described in my, 
work on the History of the European Fauna,* and across 
the lowlands of arctic Canada as indicated on pp. 46—49. 
My views on the Glacial Epoch and its nature are thus jit 
variance with those held by most geologists of the present 
time. They agree with those put forward by Sir William 
Dawson,f and are more in accordance with the current 
opinions at the time when the Glacial Epoch was spoken of 
as the “ Diluvial Age.” 
It is very generally believed, as I mentioned before, that the 
climate in northern Europe and northern North America was 
very cold, and that all that vast region which is covered by 
the deposit known as “ Glacial drift ” had been invaded during 
the Glacial Epoch by thick masses of land ice, so as to destroy 
practically all life or drive it far southward of the southern 
limits of the drift. I stated in another chapter (p. 77) that I 
did not intend to make a special point in discussing the origin 
of the Glacial Epoch. I only incidentally bring forward a 
* Scharff, R. F., “History of European Fauna,” p. 172—1S4. 
t Dawson, W., “ Ice Age in Canada.” 
