GEOLOGY OF MOUNT MARCY 7I 



Sentinel range and on Scotts Cobble, on the northern edge of the 

 Mount Marcy sheet. One series ranges from 2123 to 2172 feet in 

 altitude/ These figures, in all probability, represent the water levels 

 during the early stages of the lake. Sand plains with altitudes close 

 to i960 indicate that the lake level was undergoing constant lowering. 

 It is suggested, as a reasonable explanation of this lowering, that 

 as the small ice lobe 3 miles east of the highest peak of Ampersand 

 mountain retreated, it allowed escape through the channel of the 

 East branch of Cold brook and then south to the Van Dorrien pass 

 which held the waters to 1980 feet. 



The fault-line valley containing the Cascade lakes was probably 

 blocked by a glacial lobe and morainal material which prevented 

 escape to the east; the drainage of the South Meadows being to the 

 west as suggested above. 



Western portion of Upper Lake Newman. With the gradual 

 retreat of the ice and its constant shifting position, new and lower 

 outlets were uncovered. Succeeding the South Meadows lake the 

 western portion of Upper Lake Newman^ was ushered in. As the 

 remnants of terraces and sand plains of this level are rather indefinite 

 in character "and the range of the elevations of the surfaces is con- 

 siderable (1800 to 1895 feet), the writer is not unmindful that 

 stream -filling forming an outwash plain from the glacier may be a 

 logical explanation, yet in view of the fact that the sand plains are 

 found over a considerable area confined within- these limits, they are 

 regarded as representing a series of lake bottoms formed by a lake 

 (or series of lakes) whose level was experiencing periodic lowering 

 due to the downcutting of the controlling spillways. These spillways 

 may have been over the ice itself or a series of outlets controlled by 

 ledges of rock. Unfortunately, however, the outlets of the lake are 

 not positively known but in all probability the drainage was to the 

 west, similar to that of the South Meadows lake. 



This lake probably covered more territory than its predecessor 

 but not so much of the Mount Marcy sheet, being largely situated in 

 the Lake Placid and Saranac quadrangles. The portion of the lake 

 situated within the Marcy map assumed a four finger-shaped body 

 of water. Ice lobes lay to the east of the Wilmington notch in the 

 valley of the East branch of the Ausable preventing ahy connection 

 between the eastern and western portions of the area. 



1 Determined by a surveying aneroid barometer, corrected for temperature 

 of the air and checked against a barograph, hence as accurate as this method 

 permits. 



2 Ailing, H. L., N. Y. Mus. Bui. 207-208. 1919. 



