42 
ORIGIN OF LIFE IN AMERICA 
Epoch do not seem to me to harmonise at all with the geo¬ 
graphical distribution of animals and plants. If we assume 
that an arctic climate prevailed at that time all over Canada 
and the northern United States, we are faced by numerous 
difficulties. The biological evidence favours the view that the 
climate in boreal North America, though much more humid 
than at present, so that it led to extensive glaciation on all 
higher mountain ranges, was not arctic but temperate, and 
that in many parts within the so-called glaciated area there 
existed islands where life was abundant and survived to the 
present day. 
Let us return to the animals and plants inhabiting the 
White Mountains. Their relationship is almost altogether 
with Lapland and Greenland, and yet that affinity has clearly 
been brought about at a much earlier date than that of the 
arrival of the European element in North America. 
Luring the Pliocene Period movements seem to have taken 
place resulting in an increased height of land. This need not 
necessarily have affected the whole of North America. It was 
probably more or less confined to the north-eastern and north¬ 
western parts. While the closing of the North Atlantic left 
the coastal districts open to the beneficial influence of the 
Gulf Stream, the temperate fauna and flora must have gradu¬ 
ally disappeared from the more inland boreal parts of the con¬ 
tinent, thus leaving room for the expansion of the arctic 
animals and plants in various directions. It was during the 
Pliocene Period, I think, or earlier, and, at any rate, long 
before the commencement of the Glacial Epoch, that the 
animals and plants from Labrador thus found their way south¬ 
ward to the White Mountains. However, 1 shall bring forward 
further evidence later on which will throw additional light 
on the problems I have discussed. 
The theory that the animals and plants were driven south 
of the ice foot or southern margin of the supposed great 
ice-sheet ought to be supported by biological evidence. 
Theoretically it is assumed that the barren-ground or arctic 
fauna and flora lived close to this margin, as already stated, 
and the temperate forms further south. The only fossil evi¬ 
dences we possess of arctic animals having actually lived south 
of the ice-sheet, or, as we might say, south of the limits of 
