GEOLOGY OF LAKE PLEASANT QUADRANGLE 5 1 



Speculator village fault. Another fracture with northeast strike 

 extends through Speculator village, along the west side of Lake 

 Pleasant, between Indian Head and Lookout mountains, and nearly 

 to Fiddler's lake. The presence of this fault is shown by the pro- 

 nounced influence upon topography and the crushed zone along 

 the creek i mile southeast of Lilly lake. Through Lake Pleasant 

 its course is not exactly known, but on the Indian Lake sheet its 

 course, for some miles, is very plainly indicated by the character of 

 the topography along the western side of the Kunjamuk valley. 



Hamilton Lake fault 



This line of dislocation with northeast strike is important because 

 it bounds the great Speculator-Hamilton mountain fault block on its 

 west side. Its influence upon the topography is very marked, with 

 the development of a fault-rift valley. A broken rock zone, indi- 

 cating nearness to the fault, outcrops on the eastern shore of Hamil- 

 ton lake. The downthrow is clearly on the west side, and the 

 amount of displacement from 500 to 800 feet as far north as 

 Sucker brook. From this latter place northward for a few miles 

 the position of the fault is not so well marked. On the Indian Lake 

 sheet its course is plainly indicated by the topography on the eastern 

 side of the Kunjamuk valley. 



Hamilton Lake stream fault 



A well-defined line of fracture with strike north 30° east is 

 traceable from the southern end of Lake Pleasant southwestward 

 partly along the course of Hamilton Lake stream, thence along the 

 West Branch Sacandaga river, striking the river just above The 

 Gorge. Its topographic influence is fairly well marked. Very fine 

 examples of crushed rock zones occur in the bed of Hamilton Lake 

 stream below the mouth of Gallup creek and in the bed of the river 

 just above The Gorge (at the diabase dike). 



Piseco Lake fault 



The Piseco Lake fault must take rank as one of the most promi- 

 nent in this portion of the Adirondacks. A brief description is 

 here given because of the profound influence of this dislocation 

 upon the topography of the northwestern portion of the Lake 

 Pleasant quadrangle. It strikes northeast along the western side of 

 Piseco lake, that is, at the foot of Panther and Piseco mountains ; 

 thence just touching the northwestern corner of the Lake Pleasant 



