GEOLOGY OF FRANKLIN COUNTY 81 



"Whiteface, 4872 feet, only overtopped by four or five of the Marcy 

 peaks. Farther north is Lyon mountain, 3809 feet, the highest 

 points in Clinton county, though on the very outskirts of the hills. 

 Still farther north, beyond the outer hills, the basal beds of the 

 Potsdam sandstone constituting the edge of the high plain are 

 found, resting against the gneisses at the greatest altitude reached 

 by this plain north of the Adirondacks, and the gneisses have 

 their greatest extension to the northward along the same line. 



Passing still farther east, beyond this Line, there is a tolerably 

 rapid, often step-like, drop down to the level of Lake Champlain. 

 This descent is produced by a series of meridional faults with 

 down throw to the east, and the Champlain valley is a fault valley. 

 There is also faulting to the west of the main axis of elevation but 

 of a much less pronounced character, with the result that the 

 descent in this direction is much more gradual. 



In addition to this main north and south axis of elevation,, 

 there is also a minor east and west axis, the intersection of the 

 two being in the Marcy neighborhood. The highest summits in 

 Tranklin county, Seward, Ampersand, Morris and Stony Creek 

 Pond mountains, lie along this axis to the west of Marcy. To the 

 eastward the drop is rapid, but high peaks occur in Elizabethtown 

 .along this line. The present configuration of the northern Adiron- 

 dacks is then primarily due to dome-shaped uplifting, the Marcy 

 group of peaks denoting the point of maximum uplift. 



The Adirondack region is one of considerable elevation, and 

 erosion goes forward quite rapidly, notwithstanding the heavy 

 forest covering and the resistant character of most of the rocks. 

 So pronounced an axis of elevation must be of comparatively 

 recent formation, otherwise it could not possibly be so plainly 

 marked a topographic feature. The prominence of many of the 

 fault scarps is impressive evidence in the same direction; for the 

 'effect of long continued erosion is to wear away the raised block 

 on the one side of the fault down the level of the dropped block 

 on the other. Apparently the recent elevation of the region has 

 Deen most largely effected by means of movements along the 

 fault lines. 



