THE ADIRONDACK MOUNTAINS 



23 



been notably weakened by having been badly broken or crushed 

 due to earth movements along fractures (faults). These fault- 

 zone, stream-cut valleys are of course wholly confined to the south- 

 eastern half of the Adirondacks, and they have been produced by 

 both small and large streams. A few examples are : the Wilmington 

 notch of the Lake Placid quadrangle; Cascade lakes, Ausable lakes 

 and Avalanche Lake valleys of the Mount Marcy quadrangle, 

 Indian pass of the Santanoni quadrangle ; two valleys between moun- 

 tains in the northern half of the Schroon Lake quadrangle ; Squaw 

 Brook valley of the Indian Lake quadrangle ; and the valley of the 

 Sacandaga river just south of Wells in the Lake Pleasant quad- 

 rangle. These fault-zone valleys are usually very narrow with high, 

 nearly precipitous, rock walls on either side. They mostly trend 

 north-northeast by south-southwest in harmony with the faults. 

 Deep, narrow valleys produced by stream erosion without faulting 

 are very common in the Adirondacks. In some cases such valleys 

 are locally gorgelike, due to the fact that the stream courses have 

 been changed since the great Ice Age and the channels have been 

 cut down so rapidly that widening at the top due to weathering has 

 not yet been very effective. Among many such recently formed 

 gorges are the Ausable chasm of Clinton county cut in sandstone ; 

 the gorge of the Hudson river cut in hard rock near Stony Creek 

 station in W^arren county; and the gorge of the West branch of the 

 Sacandaga river in the western part of the Lake Pleasant quad- 

 rangle. These gorges are seldom as straight as the deep, narrow 

 channels cut out along fault zones. 



Streams 



Viewed broadly, the Adirondack drainage passes outward in all 

 directions from the central portion of the region. The waters from 

 fully two-thirds of the whole mountain area ultimately reach the 

 St Lawrence valley, while the waters from the remaining one-third 

 of the region passes into the Hudson valley (see map figure 4). 

 Inspection of the drainage map shows that a prominent division ot 

 drainage (watershed) crosses the Adirondack district irregularly in 

 a north-northeast by south-southwest direction, dividing the region 

 into two roughly equal parts. On one side nearly all the streams 

 flow northwestward to westward from this great divide, while on 

 the other side they flow eastward to southeastward from it. The 

 north, south and southwest-flowing streams out of the Adirondacks 

 are relatively of minor importance. In part this drainage divide 



