BERING STRAIT LAND BRIDGE 
99 
theory of its origin and nature which appear to me to agree 
better with the geological history of the boreal fauna and flora, 
as far as we are able to ascertain them, than the hypotheses 
which have been so widely accepted by scientific men. 
Professor Shaler * reminds us that the extension of rela¬ 
tively warm climates which has occurred at certain stages 
of the Earth’s history is perhaps explicable in an equally 
simple manner as that of the Glacial Epoch. He expresses 
the belief that if Bering Strait were as rea’dily open to the 
warm stream of the Pacific or “ Kuroshiwo ” as the Atlantic 
is open to the Gulf Stream, the temperature of the region about 
the North Pole would be lifted by at least thirty degrees above 
its present mean annual. Indeed, if the Glacial Epoch had 
been due to a simultaneous closing of the Arctic Ocean to the 
genial influences of both Atlantic and Pacific, a mild climate 
all over the Arctic Regions must have coincided with a more 
copious flow of the “ Kuroshiwo ” into the Arctic Ocean. And 
here apparently lies the great stumbling block to my theory 
on the origin of the Glacial Epoch. If the warmer tempera¬ 
ture in the Arctic Regions in Miocene and Oligocene times 
had been due to a wider Bering Strait, and, consequently, to 
the fact that a greater volume of the “ Kuroshiwo ” then 
poured into the Arctic Ocean, how are we to account for the 
faunistic affinities existing between Asia and North America 
during this part of the Tertiary Era ? There are numbers of 
animals in North America which have an Asiatic ancestry, but 
could not have entered the Continent with the great invasion 
that I described as crossing the Bering Strait land bridge. 
These and many other facts point to the existence of a land 
bridge between Asia and North America in early Tertiary 
times. All the same, several important features imply that 
before the Pliocene Period the “ Kuroshiwo ” really sent its 
warm waters altogether to the Arctic Ocean. 
As I mentioned above, no Japanese affinities are recognis¬ 
able in the American Miocene marine fauna. On the other 
hand, there is some evidence that the Miocene floras of 
Sakhalin and Japan were intimately related to the Miocene 
flora of North America. These apparently contradictory 
Shaler, N. S., “ Nature and Man in America,” p. 143. 
H 2 
