GEOLOGY OF LAKE PLEASANT QUADRANGLE 6l 



Grenville, and for this reason the highest parts of such masses as 

 Three Ponds and Wallace mountains are of Grenville. The syenites 

 and granites all appear to show ahout the same resistance to 

 weathering and erosion. 



The Paleozoic strata of the outliers occupy low valleys not so 

 much because of relative softness or weakness of the rocks, but 

 rather because they have been dropped down so far by faulting. 



DRAINAGE 



The Sacandaga river. All the drainage of the quadrangle passes 

 into the Sacandaga river, which is the most important tributary of 

 the Hudson river in the Adironda:k region. Two of the three prin- 

 cipal branches of the Sacandaga head within the quadrangle ; the 

 main stream with sources in Sacandaga lake and immediate vicin- 

 ity, and the West Branch with sources in the high Three Ponds- 

 Sugarloaf-Blue Ridge mountain mass of the south-central portion 

 of the quadrangle. 



The Sacandaga river pursues a remarkably anomalous course, 

 being in fact one of the most interesting rivers of the State in this 

 respect. Among the anomalous features of special interest are : 

 the general eastward, instead of southward, course for this part of 

 the Adirondacks ; the very circuitous course ; the crossing of a wide 

 liighland belt of hard Precambric rock instead of flowing southward 

 in the valley of much softer Paleozoic rock from Northville (Broad- 

 albin sheet) southward; and the remarkable courses of certain 

 tributaries such as Kennyetto creek. All these features are well 

 shown on the accompanying sketch map. The most roundabout 

 course is pursued by w^ater at the source of the West Branch of the 

 river, such water traveling a distance of about 88 miles ^ before 

 emptying into the Hudson river at Luzerne. Beginning under 

 Sugarloaf mountain, the West Branch flows southwestward, west- 

 ward, northward, and then eastward to a point 2^2 miles below 

 Whitehouse (Lake Pleasant sheet) where, after making an almost 

 complete circuit of 28 miles, the river is less than 4 miles from its 

 starting point (see figure 4). This peculiar course is largely due 

 to the influence of faults upon the topography, the stream chan- 

 nels almost wholly having been determined by fault lines of 

 weakness. 



^ This distance includes as nearly as possible many sharp local bends of 

 the river as shown on the various topographic maps. 



