GEOLOGY OF FRANKLIN COUNTY 77 



at least 1000 feet must be added to that amount and likely even 

 more. But at the time of their deposition the available evidence 

 indicates that the relief of the region was not as pronounced as 

 at present. The basal Potsdam is found running up to an ele- 

 vation of 1750 feet in the northern Adirondacks. With the relief 

 of the region as it is now the deposition of the minimum thickness 

 of the paleozoic rocks assigned above on this Potsdam would 

 leave none of the present peaks projecting above the general 

 level. 



Present character. At present the Adirondack region is consti- 

 tuted of ridge-like hills separated by valleys with usually a north- 

 oast and southwest trend. The hills are sometimes clustered into 

 .groups separated from one another by narrow passes, but these 

 very rugged tracts are exceptional. More commonly the valley 

 areas are considerable, and they often expand into quite wide 

 parks. The hills rise to very varying altitudes but present 

 always a general increase in hight going toward Mt Marcy and its 

 neighboring peaks. The valley bottoms show the same increase 

 in altitude in the same direction, though the amount of increase 

 is less in their case, so that the hills tower higher above the 

 valleys as Marcy is approached. The valleys are clogged with 

 drift, in part morainic, in part deposited by overloaded glacial 

 streams, and in part deposited in the beds of former lakes (see 

 pi. 1). Were the drift cleared away, they would no longer be flat 

 "bottomed as at present but have an irregular, hummocky surface, 

 as shown by the occasional protrusion of low ledges of rock above 

 the drift, by the very uneven rock surface shown along those 

 streams which have cut considerable valleys in the drift and by 

 the rock-bound character of the shores of some of the lakes which 

 still occupy valleys. 



The hills are in general subdued in outline, instead of being 

 steep and jagged. They show in the majority of cases low, gentle 

 slopes to the north or northeast and steeper slopes to the south, 

 often marked by a cliff at the top. These features are in large 

 part due to glacial action. The low, northerly slopes appear to 

 nave been much evened off by the ice sheet, are covered by a 



