BURIED CHANNELS OF THE GENESEK. 429 



postglacial. One of the largest is the channel of Kishawa creek, some 

 six miles south of Mount Morris, between the stations Sonyea and Tus- 

 carora on the Western New York and Pennsylvania railroad. A small 

 but interesting example may be seen near Swains station on the Erie 

 railroad in the channel of a small stream entering the upper Canaseraga 

 at that place; also in the Canaseraga near Dansville. In the majority 

 of cases observed these rock-cuttings occur upon the north or west sides 

 of the preglacial valleys. 



The local morainal lakes will be described later in this paper. 



BURIED CHANNELS OF THE GENESEE. 



The two old channels of greatest interest and of uncertain location are 

 those of the ancient river, one below Portageville and one past Rochester. 

 In any attempt to locate the ancient waterways it must be recognized 

 that they were broad, open valleys, comparable to the known adjacent 

 sections of the valley. The buried Genesee valley below Portageville 

 must be one to two miles wide. The writer is confident that the preglacial 

 course of the river lay through what is now Kishawa Creek valley, in 

 which lies Nunda village. This was suggested by Dr James Hall * as 

 long ago as 1840, and will probably stand as against all other suggestions. 

 The facts sustaining this opinion are out of place in this paper. 



Less confidence is felt concerning the former course past Rochester. 

 It seems most probable that below Avon the old valley turned eastward 

 and connected with the depression of Irondequoit bay. 



Sequence of Events in the geological Hestory of the Genesee 



Valley. 



introd uctor y sta temen t. 



For the fall appreciation of the lacustrine phenomena in the Genesee 

 valley it is desirable to have in mind the sequence of events in its geo- 

 logical history. Theoretically the following steps in the history may be 

 predicated : 



ERA OF PREGLACIAL SUB AERIAL EROSION. 



This was by far the longest stage in the w^hole history. From the time 

 when the region was first lifted out of its marine condition of submerg- 

 ence and sedimentation, probably during the later Devonian or the Sub- 

 carboniferous, down through the millions of years to the Glacial period, 

 this stage endured continuously. During this time the superficial rocks 



* Fourth Annual Report on the Survey of the Fourth Geological District: James Hall. New 

 York Assembly Documents, No. 50, 1840, pp. 431. 



