868 



GEOLOGY 



may be notably rough. The topography of the terminal moraine 

 may be well developed, even where the moraine as a whole does 

 not constitute much of a ridge. 1 



The surface of the terminal moraine, where well developed, is 

 generally rougher than that of the ground moraine, but more he- 

 cause the sags and swells are of smaller area and steeper slopes t lian 

 because the relief is notably more. It is not to be understood, 



Fig. 578. Topography of drift shown in contours; an area near Minneapolis, 

 Minn. Scale about one inch to' the mile. (U. S. Geol. Surv.) 



however, that this peculiar topography always affects terminal 

 moraines, or that it is confined strictly to them. The elevations 

 and depressions of the moraine may grade from strength to weak- 

 ness, and locally may even disappear, while features closely simu- 

 lating those characteristic of terminal moraines are sometimes 

 found in other parts of the drift. 



Where an ice-sheet halted in its retreat, its edge remaining in a 



1 References on terminal moraines: Chamberlin, Thin! Ann. Kept.. I". 

 Geol. Surv., 1881-2, pp. 291-402, and Amer. Jour. Sci., Vol. XXIV 

 pp. 93-97; Salisbury, Glacial Geology of New Jersey, pp. '._> ino :m.l -Ml -'><> 



