GLACIAL TOPOGRAPHY 



163 



ntes, Fig. 167), rock liasins, ponds, and marshes, and the peculiar 

 topographies resulting from the unequal erosion (PL XIII), and 

 the still more unequal deposition (Fig. 168) of drift. Surface howl- 



I iu r . 168. Skrti h of drift (terminal moraine) topography near Hackettstown, 

 N. J. (N. J. Geol. Surv.) 



ders, in many cases unlike the underlying formations of rock, and 

 sometimes in peculiar and apparently unstable positions (perched 

 bowlders) are still another mark of a glaciated area (Fig. 169). 



Fig. 169. Perched bowlder, New Jersey. 



