GLACIERS 203 
(Fig. 106) which in character and origin resembles the 
waterfall or rapid of a river. Elsewhere in the glacier 
the ice may be rent asunder, making great cracks, or 
crevasses, which reach far down into the ice, possibly 
even to the bottom. Again, the melting of the surface 
Fic. 107. 
Rough surface of Muir glacier, Alaska. 
of the ice stream often roughens it with pinnacles and 
pyramids, so that in some places the surface cannot 
even be crossed (Fig. 107). In other parts of the 
glacier, the ‘surface is much smoother and more 
easily travelled. 
Moraines. Moving down the valley, the glacier, like 
the river, is bounded by banks often of steep ascent. 
