50 NEW YORK STATE MUSEUM 



Fault at west base of Mount Dunham 



The evidence for this short, though important, fauU at the western 

 base of the Mount Dunham-Orrey ridge is largely topographic, the 

 high, very steep scarp in homogeneous syenite and nearly at right 

 angles to the strike of the foliation of the rock making the existence 

 of a fault practically certain. Where the line of fracture crosses 

 Elbow creek, a crushed rock zone may be seen but the fault can not 

 be traced north of the creek. Toward the south it terminates very 

 abruptly against a short cross-fault. A displacement of fully 600 

 feet is represented with downthrow on the west side. 



Gilmantown fault 



This well-defined dislocation, with almost due north-south strike, 

 passes through Gilmantown, along the eastern side of Gilman lake, 

 and along the western base of Burnham mountain (Indian Lake 

 sheet). The topographic influence is pronounced. Broken rock 

 zones were noted in the notch one-half of a mile south of the 

 northern map limit and along the road two-thirds of a mile south 

 of Alvord P. O. Only a few hundred feet of displacement appear 

 to be shown. 



Faults in the vicinity of Sacandaga lake and Lake Pleasant 

 Fish-Oxbow Mountain fault. That a fault line passes along the 

 eastern bases of Fish and Oxbow mountains is proved by the ridge- 

 like topography with northeast trend or nearly at right angles to 

 the strike of the foliation in the homogeneous syenite and also by 

 the presence of a shear zone in the notch one-half of a mile" due 

 south of the summit of Fish mountain. The eastern faces of both 

 Fish and Oxbow mountains are very steep scarps rising about 600 

 feet each. This fault quite certainly passes across the lake and 

 along Hatchery brook (Indian Lake sheet). The downthrow side 

 is clearly on the east. 



Fault on east side of Sacandaga lake. A line of fracture almost 

 certainly passes along the eastern side of Sacandaga lake and the 

 western base of the mountain ridge which extends southwestward 

 from Lake Pleasant village. The evidence is wholly topographic, 

 though the development of such a prominent ridge with steep 

 western face at right angles to the other structural features of the 

 region makes the existence of this fault practically certain. From 

 Indian Head southward for four miles, the displacement appears 

 to be no less than 600 to 700 feet. This fault continues into the 

 Indian Lake quadrangle along the west base of Oak Hill. 



