GEOLOGY OF THE LAKE PLACID QUADRANGLE 79 



and inaccessible Santanoni quadrangle. Probably the waters flow- 

 ing through this channel did not form a single river but consisted 

 of a chain of lakes and ponds. Just where the ice control was 

 located for each successive level is not known. 



The glacial sands, gravels etc. form a filling in the South Mead- 

 ows country that is estimated to be at least 300 feet thick. This 

 matter will be referred to again in another connection. 



A number of unmistakable beaches exist on the shoulders of the 

 Sentinel range and on Scott's cobble, northern edge of the Mt 

 Marcy sheet. The altitude of a series of them ranges from 2146 

 to 2209 feet.^ These figures, in all probability, represent the water 

 levels during the early stages of the lake. Sand plains with alti- 

 tudes close to i960 feet strongly suggest that the lake was under- 

 going constant lowering, perhaps as the small ice lobe 3 miles east 

 of the highest peak of Ampersand mountain retreated and allowed 

 escape through the channel of the East branch of Cold brook and 

 then south, lowering the level to i960 feet as set by the Van Dor- 

 rien pass mentioned above. (See figure 2 as indicated by the 

 "later outlet") 



The fault-line valley containing the Cascade lakes (Mt Marcy 

 quadrangle) was probably filled by morainal material and by a 

 glacial lobe, preventing escape to the east; thus the outlet was to 

 the west as suggested above. 



Western portion of Upper Lake Newman. With the gradual 

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

 lower outlets were exposed. Succeeding the South Meadows lake, 

 the western portion of Upper Lake Newman, as the writer pro- 

 posed to call it,^ was ushered in. As the remnants are rather indef- 

 inite in character and the range is considerable, 1800 to 1895 fe.et, 

 the writer is not unmindful that stream filling forming an outwash 

 plain from the glacier may be an alternative explanation; but in 

 view of the fact that sand plains are found over a considerable 

 area confined within definite limits of range of altitude, they are 

 assumed to represent a series of lake bottoms formed by a lake 

 whose level was experiencing periodic lowering due to the down- 

 cutting of the controlling spillways. These spillways may have 

 been over the ice itself or a series of outlets which were over rock. 

 Unfortunately, however, the outlets of the lake are not positively 



^ Determined by a surveying aneroid barometer and checked against a 

 barograph, hence as accurate as this method permits, 



2 Ailing, H. L., "Geology of the Lake Clear Region." N. Y. State Mus. 

 Bui.* 207, 208, p. 133. 



