' . GEOLOGY OF THE BROADALBIN QUADRANGLE 4I 



stone rests upon the Grenville on the west side and this is followed 

 by the Theresa formation which, on the Gloversville sheet, is fol- 

 lowed in regular order by the Little Falls dolomite. Black River- 

 Trenton limestone, and Canajoharie shale. These strata all show 

 a dip of several degrees westward due to the faulting. On the 

 downthrow side a wedge of Black River-Trenton limestone is 

 faulted against the Grenville, this limestone in turn being followed 

 in regular order (downward) by the Little Falls dolomite and 

 Theresa formation. The displacement, where the section (fig. 6) 

 crosses the fault, is about four hundred feet. 



SACANDAGA PARK FAULT 



This, the most important branch of the Noses fault within the 

 quadrangle, leaves the main line of fracture at a point about one 

 and one-half miles southwest of Sacandaga Park. The place of 

 divergence is wholly obscured by drift but the fault, which strikes 

 north-northeast, is readily traceable along the eastern foot of the 

 ridge of porphyritic granite at Sacandaga Park, thence through 

 the western edge of Northville and along the eastern foot of the 

 high hills north of Northville. The upthrow side on the west con-- 

 sists wholly of the various Precambric formations as shown on the 

 map. The downthrow side, so far as can be determined, consists 

 of Little Falls dolomite, but heavy drift completely conceals all 

 Paleozoic rocks near the fault. The nearest outcrops are dolomite, 

 such as those on the western side of Bunker hill (along the rail- 

 road) and in the little creek at the southeast edge of Northville. 

 The best evidence to show the character of the rock on the down- 

 throw side close to the fault comes from a deep well along the 

 river at the west edge of Northville. This well was drilled to a 

 depth of several hundred feet and the first rock struck is reported 

 to have been a limestone which is doubtless the Little Falls dolomite. 

 The displacement of the fault has not been accurately determined, 

 but, comparing the altitudes of the Precambric rock on opposite 

 sides, it must be at least five or six hundred feet. 



MAYFIELD FAULT 



This is a small fracture which can be distinctly traced from a 

 point just northeast of Mayfield for one and one-half miles along 

 a north 70° east strike. It probably passes through the northern 

 part of Mayfield village but is there drift covered. The fault plane 

 is almost vertical and the scarp is much more clearly shown in the 



