130 



WORK OF SNOW AND ICE 



cases the snow-field that gives rise to a glacier is restricted to a 

 relatively small depression in the side of a mountain, or in the 

 escarpment of a plateau. In such cases the snow-field and glacier 

 are hardly distinguishable, and the latter descends but little below 

 the snow-line. Such a glacier, nestled in the face of a cliff, has been 

 called a cliff glacier^ (Fig. 134). Cliff glaciers may be as wide as 



Fig. 134. A cliff glacier, coast of North Greenland. The height of the cliff 

 is perhaps 2,000 feet. The water in the foreground is the sea. 



long, and are always small. Between them and valley glaciers 

 there are all gradations (Fig. 135). Occasionally the end of a valley 

 glacier, or the edge of an ice-sheet, reaches a precipitous cliff, and the 

 end or edge of the ice breaks off and accumulates like talus below. 

 The fragments of ice may then become a coherent mass by regela- 

 tion, and the whole may resume motion. Such a glacier is called a 

 reconstructed, glacier. The precipitous cliffs of the Greenland coast 

 furnish illustrations. 



Of the foregoing types of glaciers, ice-caps far exceed all others 

 in both size and importance, while valley glaciers outrank the 

 remaining types; but since valley glaciers are the most familiar, 

 the general phenomena of glaciers will be discussed with primary 

 reference to them. 



1 Jour, of Geol., Vol. Ill, p. 888. 



