166 J. L. Rich — Physiography and Glacial Geology. 



larger valleys are not — a condition which is believed to point to 

 relatively more rapid deepening of the main valley by normal 

 stream erosion or to meandering, rather than to any effects of 

 glaciation, as the cause of the hanging valleys. 



Summary 



In a broad way the physiography of the Catskill region is 

 dominated by structural features. The region seems to 

 present clear evidence of at least two distinct erosion cycles 

 and probably of one or two other partial cycles. During the 

 earliest recognized cycle the extensive plateau north of the 

 Catskills seems to have been nearly peneplained while the 

 more resistant rocks of the mountains were reduced only to 

 advance maturity. 



The region in the latest phases of its glacial history was 

 affected by two lobes of the continental glacier : the one, a 

 branch of the Mohawk Valley lobe, pushed up Schoharie 

 Valley from the north; the other, tributary to the Hudson 

 River lobe, pushed down Schoharie Valley from the east 

 and northeast. The meeting of these two lobes has given rise 

 to a complex series of moraines in the middle Schoharie 

 Valley. 



Local glaciers within the mountains seem to have been 

 important, but further investigations are necessary before 

 their full importance can be judged. 



A glacier-dammed lake in Schoharie Valley outflowed 

 through the Central Escarpment of the Catskills at Grand 

 Gorge. Into this lake an extended series of deltas were built. 

 Since the majority of these deltas seem to have been built by 

 ice-fed streams emerging from minor tongues of ice protruding 

 from the major lobes, their detailed investigation should be of 

 prime importance in connection with the correlation of the 

 different positions of the ice front. 



No certain evidence bearing on the question of the multi- 

 plicity of glacial epochs has been found. 



University of Illinois, Urbana, 111. 



