462 NEW YORK STATE MUSEUM 



ing the crystalline area and outside o£ the Adirondacks proper is a 

 plain cut on gently dipping Palaeozoic rocks. A few outlines of 

 these Palaeozoics within the crystalline area, indicate their former 

 extent. 



The Adirondack region has been extensively faulted. Some of 

 these faults are quite recent (though all are preglacial) and form 

 conspicuous topographic features. The most recent faults run in 

 general northeast-southwest directions, and were accompanied by 

 block tilting toward the east. Drainage lines have established 

 themselves along the fault lines, the tributaries on opposite sides 

 working against a steep cliff or a gentle slope respectively. 



The trellised drainage of the Adirondacks has been noted by 

 Professor Brigham.^ 



He showed from a study of several topographic maps that the 

 main drainage lines lay along northeast-southwest valleys, and that 

 of the tributaries, the eastward flowing ones had much the longer 

 courses. The main drainage lines lie along the fault lines, and as 

 the tilting has been toward the southeast, the tributaries flowing 

 in that direction have the advantage over those flowing westward, 

 which have to cut back against the Jaces of steep fault cliffs. 



This block tilting has led to the production of a most striking 

 feature in the landscape, namely, the peculiar form of the mountains. 

 The almost universal shape of the higher hills is that of a truncated 

 cone, with steep, often precipitous faces toward the northwest and 

 long gentle slopes toward the southeast. There are some lower 

 summits' which owe their existence to the erosion of the soft lime- 

 stone from^ the valleys, such mountains of course presenting normal 

 erosion outlines. But the prevailing type is the faulted one. 

 ' " This general type of mountain, accompanied by this kind of drain- 

 age] 'is the predominant one on the Paradox Lake quadrangle, irre- 

 spective of rock type. Owl Pate, Bald Pate, Catamount and many 

 others within the anorthosite area have this outline, while among 

 the gneisses Knob, Bear and others show the same form. The 

 valleys at the foot of the steep fault cliffs often contain small rock- 

 bound lakes. 



^Am. Geol. 1898. 21:219. 



