NEW YORK STATE MUSEUM 



or uplands, with crests parallel to the river, such as are characteristic 

 of the valley west of Schenectady. There is no flood plain and there 

 is little deposit in the bed of the stream. The stream flows on bed- 

 rock and the island in the river north of Vischer Ferry is of rock. 

 The process of excavation of trie bed is still going on ; there is a fall 

 of 25 feet from the State dam at Aqueduct to a point about one mile 

 west of Vischer Ferry, a distance of about five miles. 



These features abundantly justify the conclusion that the gorge 

 is of a late geological origin. It does not follow, however, that the 

 section of the Mohawk valley above the head of the gorge extending 

 westward to Schenectady, or somewhat beyond Schenectady, be- 

 longs to the old Mohawk channel. There are evidences favorable to 

 the view that this section is in origin a part of the Ballston channel. 

 The latter merges with the Mohawk channel west of Aqueduct. It 

 seems probable that the stream from the north which in preglacial 

 times coursed through the Ballston channel joined the Mohawk at a 

 point near Schenectady. When the Mohawk was shifted from its 



Fig. 2 Sketch map showing probable preglacial drainage of the area of the Schenectady 

 quadrangle 



