Faulted Region of the Mohawk. 



47 



Korth of Mayfield the Trenton, Birdseye, Calciferous, Potsdam 

 and crystalline rocks are brought up in succession by the south- 

 erly dip, east of the fault and the wide Utica slate area ends. 

 In this vicinity it- was found that there is a branch fault to the 

 southward from the main dislocation, and a parallel fault which 

 is intersected by this branch fault. Some . of the relations are 

 shown in plate 2. The amount of these minor faults is not 

 great and they appear to affect a relatively small area. The out- 

 crops upon which my knowledge of their relations is based are 

 not as numerous as could be desired, for there is considerable 

 drift over the region. The outcrops observed and the structural 

 deductions are represented in the map and sections on page 46. 



There are some indications in the topography that the minor 

 parallel fault extends across the Sacandaga and up the depression 

 in which Hope Falls are located. ISTorth of Northfield both faults 

 are entirely in crystalline rocks and their courses were not 

 specially studied. Two miles west of Korthfield there is a small 

 area of Calciferous apparently completely surrounded by crystal- 

 line rocks and abutting against the "Noses" fault on its west 

 side. 



Fifteen miks north of Northfield, at Wells village, in the 

 Sacandaga valley, an area of Paleozoic rocks was found lying 

 against a fault scarp on its western side, and possibly faulted on 

 the east side also. Its relations are shown in the following 

 figure. 





-^^i^ 







Figure 9.— Cross section of Sacandaga valley at Wells, Hamilton county, N. Y., looking north. 

 C7. Utica slate. T. Trenton limestone. C. Calciferous. P. Potsdam. ^. Crystalline rocks. Z». Drift. 



The Utica and Trenton formations are characterized by an 

 abundant fauna. The Calciferous and Potsdam formations have 

 their usual characteristics. The Utica slate and Trenton lime- 

 stone are exposed very near the crystalline rocks on the west 

 side, and they dip gently westward. 



