82 NEW YORK STATE MUSEUM 



Both of the uplifts of the region which have been mentioned 

 were of the same nature, being greatest in 'the Marcy vicinity and 

 diminishing thence in all directions. This is shown by the fact 

 that the two base levels are separated by greater and greater 

 vertical distances in going toward Marcy from any direction.. 

 Unfortunately definite figures are lacking, but in general the 

 valley bottoms range from 1500 to 2000 feet in altitude in the 

 heart of the Adirondacks and are 1000 feet lower than that over 

 a large part of St Lawrence county. The hills are only a few 

 hundred feet above the valleys in that county, whereas they range 

 from 1000 to 1500 feet above in Franklin county, 1 leaving the 

 higher summits entirely out of the question. 



The Potsdam sandstone furnishes a good measure of the 

 amount of warping which the periphery of the Adirondack region 

 has undergone about the north and south axis since that rock was- 

 deposited. On that axis the basal bed reaches an altitude of 

 about 1400' A. T. (the still higher Potsdam is found in depressions- 

 running back into the hills, and is not here considered). Going 

 toward Lake Ohamplain, faults drop it down below the level of 

 the lake, 101' A. T., within a very short distance. Along Lake 

 Ohamplain it lies mostly far below sea level, rocks many hundreds 

 of feet higher in the scale being at the surface. Going westward 

 across Franklin county and into St Lawrence, the altitude falls* 

 more slowly and steadily, so that in the neighborhood of Pots- 

 dam, about 50 miles distant, these beds lie from 600 to 800 feet 

 lower than at their highest point. These figures represent the 

 total amount of warping along this line since the deposition of 

 the paleozoic rocks, subject to an unknown correction depending 

 on the variations in altitude of the floor on which the deposition 

 took place. That this floor was irregular is certain, that is> it 

 consisted of low ridges and valleys, but these are mere local 1 

 irregularities. That this surface was canted at this time there is- 

 no evidence. 



lit must be borne in mind that only the northern Adirondacks are under 

 consideration. For a long distance to the southwest from Marcy the* 

 valley levels drop little, if any. 



