122 
THE ICE AGES, PAST AND FUTURE. 
June, 1892. 
mountain regions to the lower plains ; and they are finally left 
stranded at the foot of the glacier, or dropped higher up 
when the glacier subsequently retreats on account of the 
melting of the ice being then at a greater rate than its supply. 
This process is seen regularly going on at the present day in 
the glaciers of Switzerland and Norway, in the elevated 
mountainous regions of those countries where the temperature 
is low enough, on account of their elevation, to retain ice 
continuously frozen all the year round. 
The second kind of evidence of the Ice Age is the 
occurrence of extensive longitudinal grooving and striation of 
the exposed rocky sides of the valleys leading from the 
northern mountainous parts ; which can only be accounted 
for by the passage of a glacier that filled up the valley 
carrying imbedded in it numerous fragments of hard rock, 
that have acted as cutting and grooving tools of enormous 
power, under the pressure of the superincumbent weight of 
many hundreds, and in many cases no doubt, thousands of 
feet thickness of ice in the glacier. This grooving and 
striation of the rocks is distinctly seen in numerous cases 
in the valleys of this country; and in Norway it is shown on 
a gigantic scale, extending to a height of more than 3,000 feet 
up the valley sides, showing that they were at some former 
time filled up to that level by glaciers, which ground away the 
exposed faces of the rocks in their continuous flow. 
There is one other country, Greenland, that directly 
illustrates at the present day the state of things that must 
have existed in this country at the period of the Ice Age. 
Greenland is now completely covered with an enormous sheet 
of ice, which has been ascertained to extend in the middle of 
the country to a height of 8,000 feet above the sea, and may 
be considerably higher further north. This ice mass is 
constantly flowing down to the sea, on both the east and 
west coasts, in numerous gigantic glaciers, which terminate 
in abrupt ice cliffs at the sea shore, that are continually 
breaking off and forming enormous icebergs. These gigantic 
glaciers are far beyond the Swiss and Norwegian glaciers in 
size and extent, and in the rate of their motion, and they 
travel nearly as much in a day as those do in a whole year. 
In connection with this subject a special interest attaches 
to the recent remarkable exploration of Greenland by Dr. 
Nansen, who succeeded in crossing for the first time the 
gigantic mass of snow and ice, extending no less than 260 
miles in width from sea to sea; and he was thus enabled to 
study the circumstances similar to those that must have 
existed in this country at the time of the Ice Age. Greenland 
is an immense extent of country, nearly 2,000 miles in length 
