60 A. EF. Verrill—The Bermuda Islands; Geology. 
Therefore, it is certain that the northerly winds would have been 
cooler than at present and doubtless the contrasts in temperature 
between the northerly and southerly currents, both of air and water, 
would have been much greater than now. Therefore, we are safe 
in assuming that the climate would have been more stormy, with 
fiercer gales and much more rain than now. Probably there were 
also frosts regularly in winter, and perhaps some snow, for light 
frosts sometimes occur in Bermuda even now, and sometimes a few 
snow flakes also. 
Such changes in the climate as I have named would have needed 
only a few degrees of decrease in the mean annual temperature. 
But they would have been sufficient to exterminate most of the 
tropical and subtropical life that may have existed there previously. 
The forests and other vegetation may have quite disappeared then 
from the exposed hills and highlands, even if partially retained in 
the sheltered valleys. Death of the vegetation and the increased 
violence of the winds would have set the sands in active motion 
again, perhaps far more energetically than ever before. 
These, I suppose, were the conditions under which the land 
attained its greatest elevation and extent. 
8. Post-glacial Bermuda; Subsidence. 
During the decline of the long glacial period, the “ Greater Ber- 
muda,” like the American coast north of it, underwent a gradual 
subsidence, as shown by many geological phenomena. This is 
believed to have amounted eventually to at least 100 to 120 feet, as 
will be shown in a later chapter. 
This period probably corresponded to the Champlain or Lawren- 
tian period of eastern North America. During this long period of 
subsidence there was an immense amount of erosion by the sea, and 
much of the lower parts of the previous dry land of the interior was 
finally covered by the sea, gradually bringing about the present con- 
dition of things. New sand-drift rocks were also forming during all 
this period. During this period, also, many species of plants and 
animals were introduced from North America and the West Indies 
then referred to, I now refer to the post-glacial or Champlain period. However, 
it is possible that the Gulf Stream waters were as warm in the glacial period as 
at present, and that owing to the elevation of the coasts of the boreal Atlantic, 
and probably of its entire sea bed, its current may have reached Bermuda more 
directly than at present, so as to offset the cold Arctic currents. 
