92 NEV/ YORK STATE MUSEUM 



Cheney pond was a small natural pond in the northern part of 

 the basin now occupied by the large body of water of the same 

 name, the building of Lester dam having raised the water to the 

 present level. 



Brace dam no longer holds back the water of Boreas river as 

 shown on the map. 



Hewitt pond occupies a rather delicately balanced position as 

 regards its outlet. A trench, perhaps not more than lo feet deep, 

 cut through the narrow barrier of loose glacial drift along its south- 

 western side would allow the pond to drain westward into the 

 Boreas and Hudson rivers, instead of eastward as now into the 

 Schroon river. 



The other ponds of this region require no special description. 



Postglacial Changes of Level 



It is a well-known fact that, during the closing stages of the Ice 

 Age and just afterward, northern New York, including the area 

 of the Schroon Lake quadrangle, was submerged hundreds of feet 

 below the present altitude, and that tide water extended through 

 the Champlain valley. This is proved by the presence of marine 

 beaches with fossils several hundred feet above sea level in the 

 Champlain valley. The most recent earth movement in northern 

 New York has been that which has brought the marine deposits to 

 their present position above sea level. This earth movement has 

 been differential with greatest uplift toward the north, the rate of 

 increase northward having been several feet a mile. The differen- 

 tial uplift appears to be clearly recorded within the Schroon Lake 

 and adjoining Paradox Lake and North Creek quadrangles where, 

 as already shown, the delta terraces and sand plains of former 

 glacial Lake Pottersville gradually increase in altitude northward 

 at the rate of several feet a mile. The deposits in glacial Lake 

 Minerva also seem to show a similar uplift, but the evidence there 

 ts not so decisive. 



