216 ELEMENTARY GEOLOGY 
irresistible power of the ice. We may fairly believe 
that, as the great continental glacier slowly passes over 
the land, it grinds its bed, just as the valley glaciers 
do. Probably it is wearing down the hills and deepen- 
ing the valleys,.and perhaps even gouging out rock 
basins. In the great sheets of ice which now exist, we 
no doubt have an illustration of the conditions from 
which the northeastern part of North America, and 
the northwestern part of Hurope have recently 
escaped (p. 475). 
Piedmont Glaciers.— Within a few years a new type 
of glacier has been described from Alaska. This is the 
Malaspina glacier, which covers the plain between the 
sea and the base of Mount Saint Elias, from which the 
glacier is fed by a number of valley glaciers, reaching 
from the great snow fields of the lofty mountains. 
There are many interesting features connected? with 
this glacier, one of the most notable of which is, that 
the motion near the margin has so decreased that a 
forest is able to grow upon the surface of the glacier 
(Fig. 121). The soil in which it grows, is the moraine 
that has accumulated to a considerable depth on the 
margin of the nearly stagnant glacier. The cause for 
the almost entire absence of motion is the fact that 
1 Tt is impossible to give more space to their consideration. A descrip- 
tion of them may be found in articles by Prof. I. C. Russell in Vol. IIL, 
pp. 58-203, of the Natural Geographic Magazine and the Thirteenth Annual 
Report of the U. S Geological Survey, pp. 1-91. 
