96 NEW YORK STATE MUSEUM 



Much of the faulting of the eastern and southern Adirondacks 

 dates from the time of this peneplain uplift or even later, though 

 it is likely that some took place much earlier. 



Immediately preceding and probably during much of the great 

 Ice Age, this region, like all the northeastern United States, was 

 considerably higher than now, as proved by such drowned river 

 channels as the lower Hudson and St Lawrence. 



During the Ice Age of the Quaternary period, the area of the 

 quadrangle, in common with nearly all of New York State, was 

 buried under the great ice sheet which has left many records, such 

 as striae on the ledges, glacial boulders, moraines and glacial 

 deposits in general. The preglacial topography was not profoundly 

 affected by ice erosion and deposition. The many extinct and 

 existing lakes of the quadrangle were formed either by actual pres- 

 ence of the ice dam itself or, more commonly, by irregular deposits 

 of drift across old stream channels. 



A subsidence of the land several hundred feet below the present 

 level took place toward the closing stages of the Ice Age or imme- 

 diately after for this latitude, when arms of the sea extended 

 through the Champlain and St Lawrence valleys. The area of the 

 Schroon Lake quadrangle was then, of course, lower than now. 



The most recent movement of the land has been a differential 

 uplift with greater elevation toward the north. At the latitude 

 of the Schroon Lake quadrangle, this postglacial uplift has 

 amounted to several hundred feet with greater uplift toward the 

 north, the rate of increase in elevation northward having been 

 several feet a mile. The differential character of this uplift is 

 well shown by the delta deposits of the extinct glacial Lake 

 Pottersville. 



MINES AND QUARRIES 

 Graphite 



A graphite mine is located at the western base of Catamount hill 

 about 10 or 15 rods northeast of the confluence of Trout and Alder 

 brooks. The mine has not been in 'operation for several years, 

 but the buildings still stand, and a considerable quantity of the 

 graphite-bearing rock is piled up. 



The mine workings are located on a belt of Grenville biotite- 

 graphite schist some 30 or 40 feet wide. Most of the rock of this 

 belt is in very thin layers and contains tiny'flakes of graphite, but 

 one zone in it, a few feet wide, is extra rich in large thin flakes 



