THE INTERGLACIAL GORGE PROBLEM 151 



Summary. — Briefly summarized, this paper is intended to show 

 the existence of a series of complex gorges which are considered 

 interglacial. The minimum number of epochs of deglaciation is 

 two ; the maximum number, four. The amount of ice recession 

 was probably sufificient, in at least one case, to permit a north- 

 ward drainage. The length of the epochs of deglaciation can be 

 only roughly estimated, but the shortest was probably as long as 

 postglacial time, and the others were doubtless much longer. 

 The main trenching of the broad valleys was interglacial, and 

 the minimum amount of interglacial elevation is placed at 250 

 feet. The land is probably more than 250 feet higher at the 

 present time that it was during the time of the formation of the 

 broad valleys of Cayuga Lake region. 



George C. Matson. 

 Champaign, 111. 



