PLEISTOCENE GEOLOGY OF THE ADIRONDACKS 635 



The next paper was read by title. It was 



PLEISTOCENE FEATURES IN NORTHERN NEW YORK 

 BY H. L. FAIRCHILD 



Then the Society listened to the reading of 



PLEISTOCENE GEOLOGY OF THE SOUTHWESTERN SLOPE OF THE 

 ADIRONDACKS 



BY WILLIAM J. MILLER 1 



[Abstract] 



The area discussed in this paper is about 60 miles long and 15 miles wide, 

 and extends from Lowville to Dolgeville, New York. The northern portion of 

 the area is occupied by the Black River valley and the southern portion slopes 

 southward toward the Mohawk river. 



Some years ago Professor Chamberlin suggested that tongues of ice flowed 

 around the Adirondacks and met in the Mohawk valley. 2 Observations by the 

 writer along the southwestern Adirondacks have an important bearing upon 

 this question of ice movement in northern New York. In the Black River 

 valley the stria? point from south 25° to 40° east and parallel to the strike of 

 the valley, thus showing the influence of the valley in determining the direc- 

 tion of flow. Southward, on the Little Falls sheet, the stria? point more nearly 

 east and west, and show a direction of flow parallel to the Mohawk valley. It 

 has already been established that the ice current was southwesterly through 

 the Saint Lawrence valley and southerly through the Champlain valley, and 

 also that an ice tongue moved westerly up the lower Mohawk valley to meet an 

 easterly flowing tongue from the upper Mohawk valley. During the height of 

 glaciation the main ice current was southwesterly across the Adirondack re- 

 gion. This is shown by numerous glacial stria? in the midst of the Adiron- 

 dacks and to the south of the Mohawk valley, as well as by the distribution of 

 erratics from the Adirondacks to the south and southwest of the mountains. 

 Bearing in mind all the facts, the writer is led to the conclusion that when 

 the ice, in its southward movement, struck the Adirondacks, it was divided 

 into two currents flowing around the mountains and meeting in the Mohawk 

 valley ; that during maximum glaciation there was a strong southwesterly 

 current, but that border currents continued as undercurrents more or less 

 checked in velocity, and that after the disappearance of the ice-sheet from the 

 central Adirondacks border currents were maintained. 



There is no evidence to show that ice erosion did any very deep cutting into 

 the pre-Cambrian rocks, but it was much more effective upon the Palezoic sed- 

 iments. The writer believes that in the Black River valley we have one of the 

 best examples of ice erosion in northern New York. Black river follows close 

 to the Paleozoic-pre-Cambrian boundary line, and the Paleozoics, having a 

 thickness of nearly 1,500 feet, overlap upon the pre-Cambrians. On the Port 



Introduced by W. B. Clark. 



Third Annual Report, U. S. Geological Survey, 1881-2, pp. 360-365. 



