Faulted Region of the Mohawk. 45 



broken and crushed. Its usual dip at and near the Mohawk is 

 gently to the east ; near Currytown it is west, for the most part 

 gently, but at one point 40°. The amount of dislocation along 

 the fault is about 300 feet at the Mohawk river. 



ISTorth from the river the great scarp to which this fault gives 

 rise extends for many miles as a high wall along the west side of 

 the great Utica slate area of Johnstown and Gloversville. For 

 the first six miles this wall consists of the Calciferous sandrock 

 with underl3ang crystalline rocks occasionally exposed where 

 brooklets cut into the Utica slates. With the general upward 

 pitch to the north and some increase in the throw of the fault, 

 the surface of the crystalline rocks gradually increases in alti- 

 tude, and southwest of Johnstown it extends to the crest of the 

 fault scarp. The Calciferous then trends off to the west as a ter- 

 race and the crystalline rock area expands into a wide high 

 plateau capped by a few small outliers of Potsdam sandstone. 

 The Utica slates lying to the east of the^fault are exposed at 

 many points with the usual sharp dip to the eastward in the 

 immediate proximity of the fault plane. On the turnpike, at a 

 point about three miles west of Johnstown, the average dip of the 

 shales is 40°, and in several exposures south of here dips of 60° 

 were noticed. This disturbance was found to extend from 5 

 to 8u0 yards from the fault, the eastward dip gradually dying out 

 and giving place to the general monoclinal inclination to the 

 southwest. Although the fault plane was not observed in this 

 region, there are several exposures in which it is clearly seen to 

 be vertical or very nearly so. One is in the banks of a creek 

 which falls over the fault scarp of crystalline rocks in a long 

 succession of cascades. Near the bottom there is a bank in which 

 a sheer wall of crystalline rocks is seen along the fault plane. 

 There is much debris banked against it but the Utica slate out- 

 crops at several points near by in the gorge and within a few 

 inches of the contact in the road above. 



In the region west of Johnstown, I found a branch fault ex- 

 tending southwestward from the main dislocation to a point 

 south of Ephratah. Its relations are shown in section B, plate 3, 

 just under the B and also on plate 2. The downthrow is on its 

 western side and it gives rise to a conspicuous scarp of crystalline 

 rocks and Calciferous, facing northwest. Its maximum throw is 



