THE PLEISTOCENE OR GLACIAL PERIOD. 



371 



the melting of the ice, had somewhat the form of terraces, while their 

 slopes and upper surfaces had something of the topography of kames. 



Fig. 500. — Diagram to illustrate deposition between stagnant or nearly stagnant 

 ice, and the wall of the valley in which it lies. 



Such terraces have been called kame terraces 1 (Fig. 501). This type 

 of stratified drift finds abundant illustration in the Appalachian moun- 

 tain region and in New England. 



Fig. 501. — Diagram to illustrate kame terraces. ABC represents the stratified drift 

 of the kame terraces which are underlain by ground moraine. Till also covers 

 the valley bottom. 



(2) Beyond the edge of the ice. — When the waters issuing from the 

 ice found themselves in valleys, and when they possessed sufficient 

 load and not too great velocity, they aggraded their valleys, developing 

 valley trains, 2 which often extended far beyond the unstratified drift 

 with which they were contemporaneous. Valley trains are usually 

 associated with stout terminal moraines (Fig. 502). A protracted 



J°r?/>* y 



Vo//ey 



Fig. 502. — Diagram to illustrate the profile of a valley train and its relation to the 

 terminal moraine in which it heads. 



stationary stand of the ice-edge is as necessary for great aggradation 

 of the valley below, as for the development of the terminal moraine. 



Salisbury, op. cit., pp. 156 and 121-124 respectively. 



2 3d Ann. Rept. U. S. Geol. Surv., and Jour, of Geol , Vol. I, p. 534. 



