138 J. L. Rich — Physiography and Glacial Geology 



Physiography. 



General Statement. 



The region described is that portion of the Allegheny 

 Plateau of Eastern United States lying in eastern New York 

 in the angle between the Mohawk Yalley lowland on the north 

 and the Hudson River lowland on the east, and extending 

 southward to include the northern Catskill Mountains. 



Fig. 1. 



Fig. 1. Key map. 



The region is underlain by sedimentary rocks of varying 

 character which, though everywhere nearly horizontal, dip at 

 low angles toward the south and southwest. The more resist- 

 ant beds, such as the Lower Devonian limestones, the Hamil- 

 ton shales and sandstones, and the Catskill sandstones and 

 conglomerates, are each marked by cuestas* presenting steep 



* Grabau, A. W. (Geology and Paleontology of the Schoharie Valley, N. Y. 

 State Museum Bull. 92, 1906, pp. 333-348) describes some of the features 

 here mentioned. 



