190 
of nearly 4.5 million square miles, that is nearly one and a half 
tines that of the United States. The ice was so thick as to com- 
pletely bury even the highest summits in New England, viz., Mt. 
Greylock in Massachusetts (3533 feet), Mt. Mansfield in Ver- 
mont (4406 feet), Mt. Washington in the White Mountains 
(6284 feet), and Mt. Katahdin in Maine (5265 feet). In the 
center of Labrador the ice probably was as much as 14,000 feet or 
over two and one-half miles thick. In 1931 the Greenland ice shect 
was found, by sonic soundings, to average about one mile thick. 
To give a further idea of the importance of this glaciation it may 
mae 
be mentioned that there was also a smaller ice sheet in northern [u- 
rope covering the Scandinavian countries, the Baltic Basin, northern 
There were finally extensive 
Germany, and northwestern Russia. 
ice-caps and glaciers in the Arctic, the British Isles, the Alps, Asia, 
southern South America, and elsewhere. The volume of the ice at 
the climax of the glaciation in excess of the existing quantity has 
been calculated at nearly 8 million cubic miles. We get some idea 
of the immensity of this quantity when we realize that it corre- 
sponds to a water layer 300 to 325 feet thick over all the oceans. 
Of course, the water from which the ice was made came from 
the oceans. Water taken from the sea by evaporation into the air 
by the winds over the land where it fell as snow and 
was carried 
As a result, the 
was stored in the growing ice sheets and glaciers. 
level of the sea subsided. Ultimately the ocean surface thus prob- 
ably stood 300 to 325 feet lower than it does today. The condi- 
tions were complicated by vertical movements of the earth’s crust, 
especially depression of the ice-covered areas by the added weight 
of the ice, but on the whole the shores lay far outside the modern 
ones. Long Island may have had the shape of a large triangle 
with a point at either end of the modern island and another about 
70 miles south of the present southern shore. Its southwestern 
boundary was formed by the then Hudson River whose channel is 
distinctly recognizable, and whose mouth lay some 95 miles south- 
west of Sandy Hook. 
Flora and Fauna Driven Southward 
When the ice expanded, northern species of plants and animals 
were driven southward. They kept the present arrangement in 
