516 J. H. STOLLER HISTORY OF MOHAWK-HUDSON REGION 



The features discussed are within the areas covered by the Schenectady, 

 Saratoga, Cohoes, and Schuylerville topographic sheets. 



Previous Interpretations 



Woodworth was the first to refer to (in connection with glacial history) 

 the preglacial rock channel trending northeasterly from near Schenec- 

 tady, named by him the Ballston Channel. He pointed out that the 

 channel is dependent on structure, and that "erosion in Pleistocene times 

 has excavated the channel along the vertical beds, which are evidently 

 separated from the horizontal strata on the cast wall of the valley by a 

 fault. " He made no reference to the origin of Ballston Lake, which occu- 

 pies a portion of the bottom of the channel. In regard to Saratoga Lake 

 and Round Lake Woodworth- stated as a probability that they are "un- 

 filled depressions marking the site of an old valley west of the present 

 Hudson gorge." 



The writer was the first to call attention to the topographic evidence 

 that Ballston Channel afforded a passage for the Hooded Mohawk, when 

 blocked by the emerging delta deposits at Schenectady due to the subsi- 

 dence of the Lake Albany waters, and to the clearly marked erosional 

 features produced by the deflected currents. 3 He suggested that Ballston 

 Lake occupies a portion of the Ballston Channel which has been more 

 deeply gouged out by ice erosion than elsewhere. In regard to Round 

 Lake he considered that the broad basin, surrounded by slopes of Pleisto- 

 cene clays and sands, at the bottom of which Round Lake lies, was caused 

 by the erosive work of the flooded Mohawk waters at that stage in the 

 subsidence of Lake Albany when the Mohawk currents were diverted from 

 the Ballston Channel southeastward toward the Hudson Valley at Me- 

 ehanicville. 



In regard to the present course of the Mohawk, the writer considered 

 Hint the gorge beginning at Aqueduct, three miles below Schenectady, 

 and extending to Cohoes originated as due to erosion by overflow waters 

 from the Ballston Channel at times when the Mohawk hoods were at their 

 maximum, and that the spillway thus established was gradually deepened 

 into a gorge and the northward course of the Mohawk thus eventually 

 undercut. 



Fairchild reached the same conclusion as the writer in regard to the 

 deflection of the Mohawk waters through the Ballston Channel, and from 

 the Ballston Channel southeast wardly toward Mechanicville. 4 He ex- 



2 J. B. Woodworth : N. Y. State Mus. Bull. No. 84, p. 75. 



3 .T. H. Stoller : N. Y. State Mus. Bull. No. 154, pp. 30-33. 



4 II. L. Fairchild: N. Y. State Mus. Bull. Nos. 200, 210, p. 38. 



