THE WORK OF SNOW AND ICE 



267 



several hundred feet high, or even as much as a thousand. In 

 northern Italy a lateral moraine is said to be about 2,000 feet high. 1 

 Most of the material which was englacial during its transpor- 

 tation becomes either subglacial or superglacial before deposition, 

 for it reaches the bottom or the top of the ice before being deposited. 

 Only where the ends or edges of a glacier are vertical or nearly so, 

 as in the arctic regions, does deposition take place from the engla- 

 cial position directly. 



Fig. 222. A lateral moraine left by a former glacier in the Bighorn Moun- 

 tains of Wyoming. (Photo, by Blackwelder.) 



Distinctive nature of glacial deposits. The deposits made by 

 glaciers are distinctive. In the first place, the ice does not assort 

 its material, and bowlders, cobbles, pebbles, sand, and clay are con- 

 fusedly commingled (Fig. 223). In this respect, the deposits of 

 ice differ notably from the deposits of water. Furthermore, many 

 stones of the drift show the peculiar type of wear which glaciers 

 inflict. Though notably worn, they are not rounded like the stones 

 carried by rivers. Many of them have sub-angular forms with 

 planed and beveled faces, the planes being striated and bruised 

 (Fig. 205). Absence of stratification, physical heterogeneity, and 

 the striation of at least a part of the stones are among the most 

 distinctive characteristics of glacial drift. A not less real though 



1 Geikie. The Great Ice Age, 3d ed., p. 529. 



