THE WORK OF SNOW AND ICE 



105 



a mountain valley, the ice moves down the valley. Such a glacier is 

 a valley glacier (Fig. 110). In high latitudes, snow-fields and the 

 fields of ice to which the snow-fields give rise sometimes lie on plains 

 or plateaus. When the ice in such situations begins to spread, it 



90 100 110 



Fig. 108. Map of Antarctica. The dotted line represents the approximate 

 limit of abundant floating ice. (After Bartholomew.) 



moves in all directions from its center. Such glaciers may be nearly 

 circular, and are called ice-caps or ice-sheets, or, if very large, conti- 

 nental glaciers. The main ice-caps of Antarctica and Greenland 

 (Fig. 108) are large, but small ones of the same type are found on 

 various promontories along the coast of Greenland, on Iceland 

 (Fig. 109), and on some Arctic islands. 



