THE WORK OF SNOW AND ICE 



123 



left in the valley when the ice melts, but they are commonly too 

 small to be conspicuous after the ice is gone. But the lateral 

 moraines which remain after a valley glacier has shrunk or dis- 

 appeared are often very large (Figs. 129 and 130). They are hun- 

 dreds of feet high in many cases and rarely more than a thousand. 



Fig. 129. The lateral moraines of the Argentiere Glacier, Switzerland. 



The highest lateral moraine known, about 2,000 feet high, is in 

 northern Italy. It was made by a giant glacier which once came 

 down from the Alps. 



A valley glacier moves from its center toward either side, as 

 well as down its valley, and as it spreads sidewise from the center, 

 it is constantly shifting debris from the axis of the valley to the edge 

 of the ice on either side. The lateral moraine left after the ice is 

 gone, is therefore of the nature of a terminal moraine beneath the side 

 if the ice. Ice-caps do not develop lateral moraines. 



Disposition of the drift. Glaciers leave their drift very un- 

 evenly distributed over the surface which they once covered. The 

 drift of a terminal moraine is generally much thicker than that of 

 the ground moraine near at hand, while the drift of lateral moraines 



