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NEW YORK STATE MUSEUM 



lions to the high ground and the ice body, do not favor the 

 idea of very great erosion by the ice, though some ice abrasion 

 seems quite probable. The surface form of the crystallines on 

 the north side of the channel may possibly be due to ice abrasion, 

 but no positive evidence was found by the writer. The present 

 form of the rock channel at Little Falls is chiefly, if not entirely, 

 the product of river erosion. 



Stream erosion 



The investigation of one other locality will determine the 

 limit of hight for the Little Falls col as it was left by the 

 glacier. 



About 4 miles south # of Little Falls is a low pass through the 

 hills, leading to Newville village and the Nowadaga creek 

 and to the Mohawk valley at Indian Castle. The writer has 

 not been on this col, but the gap can be seen from the New York 

 Central Eailroad and from the electric road; and the fact that 

 the pass carried glacial waters is proved by the conspicuous 

 lines of stream cutting plainly to be seen on the slopes south 

 of Jacksonburg and 4 miles southwest of Little Falls. This 

 makes it certain that the Glaciomohawk waters found the col 

 at Little Falls, as left by the ice, lower than the col among the 

 hills on the south even after the stream-cutting of the latter; 

 otherwise the waters could not have deserted the southern for the 

 northern outlet. The Jacksonburg drainage cuts were made by the 

 high-level waters escaping past the ice lobe resting in the valley. 

 When the Mohawk valley was deserted by the ice, the Little Falls 

 pass took the drainage. The present altitude of the southern 

 pass, which is given by the map as 740 to 760 feet, makes the 

 limit for the possible thickness of drift left on the 600 foot rock 

 terrace at Little Falls as about 150 feet. 



The Archaean rock has no drift on it now, and is apparently all 

 water-swept [see pi. 15-19]. As the surface declines southward 

 about 100 feet in the width of the channel, it seems evident 

 that some kind of filling on the col was necessary to hold the 

 stream to its work against the north side. It would appear 

 that the postglacial stream began its work by cutting across 

 the col on the north side; that the resistance of the crystalline 



