GLACIERS 219 
WORK OF GLACIERS (continued) 
They scour the rocks over which they pass and 
grind both these and the materials carried, forming 
EROSION. : : s 
clay. Rocks striated and polished. Hills and val- 
leys worn as ice passes over them. 
TRANSPORTA- Carries rock fragments of large and small size side 
TION. by side in the moraines of various kinds. 
Moraines of hummocky outline, and unassorted 
clay and bowlders left by the ice. Ice-born streams 
deposit assorted beds of stratified sand and gravel. 
_ Deposition. | Lakes often formed by dams of these accumulations. 
In the sea, icebergs aid in the distribution of the 
rock materials; and at the margin of the ice which 
enters the sea, deposits are made directly. 
