GEOLOGY OF MOUNT MARCY 73 



Eastern Section 



The Keene lake. During most of the life of the western portion 

 of Upper Lake Newman, the ice lobe in the valley of the East branch 

 of the Ausable was retreating northward and allowed a growing 

 body of water to accumulate in the Keene valley. This body of 

 water, named the Keene lake, left terraces high up on the valley 

 walls, especially in the brook valleys where the present streams have 

 bisected them. The sands on the East hill, near Hurricane Lodge, at 

 2000 feet altitude, were probably deposited at this time. The lake 

 filled Keene valley and thus was located mainly within the confines of 

 the Mount Marcy sheet. 



The outlet is at present believed to have been south through the 

 double fault-line valley in which the Ausable lakes are now located 

 into standing waters in the northern half of the Schroon Lake sheet. 

 The two passes to the east, the Spruce Hill pass, and the Chapel 

 Pond pass, although much lower than the surface of the water, were 

 apparently effectively blocked by lateral ice lobes forced into them 

 from the east, being tongues of the ice body occupying the Elizabeth- 

 town-Pleasant valley, thus making escape to the east impossible. 

 Studies of these two passes lead to the above conclusion. 



The eastern end of the Wilmington notch was uncovered by the 

 retreat of the ice that dammed the Keene valley, furnishing a connec- 

 tion with the western portion of the area, permitting the waters in 

 the valley of the East branch to fall to the level of Upper Lake 

 Newman. 



During the life of the Keene lake the area south of the Upper 

 Ausable lake was flooded; an ice dam lay in an east and west line 

 across the upper portion of the Schroon Lake quadrangle.^ As this 

 ice wall melted the waters south of the divide were separated from 

 the Keene lake so that the Boreas-Elk-Clear pond section became a 

 distinct glacial lake, which in turn may have been subdivided into the 

 Boreas lake and glacial Elk lake, while the drainage of the remain- 

 ing Keene lake flowed into the Boreas lake through the pass east of 

 Moose mountain, until extinguished by the formation of Upper Lake 

 Newman. 



Upper Lake Newman. The life of the eastern portion of Upper 

 Lake Newman was probably relatively short compared with that of 

 the western area, for the terraces are very indefinite and the separa- 

 tion of the benches into an upper and a lower series does not exist, 

 or at least can not be demonstrated. Thus soon after the establish- 



1 Fairchild, H. L., N. Y. State Mus. Bui. i6o, pi. I2. 



