GEOLOGY OF THE BROADALBIN QUADRANGLE 43 



Cranberry Creek village the fault is clearly traceable as a topo- 

 graphic feature and by frequent outcrops of fault breccia. On 

 the west side of Bunker hill a small mass of Trenton limestone is 

 faulted against lower (cherty) beds of the dolomite so that the 

 amount of displacement is here approximately represented by the 

 thickness of the dolomite formation or about two hundred feet. 



NORTHVILLE FAULT 



This fault passes through the depression just east of the village 

 of Northville. Its strike is nearly north and south and the upthrow 

 side is clearly on the east. The relations are well shown at only 

 one point and this is along the creek at the southeastern edge of 

 the village. Here are exposed about twenty-five feet of hori- 

 zontal, cherty Little Falls beds, the rocks being considerably broken 

 or brecciated. Within two hundred yards eastward and on the 

 hillside are large outcrops of Precambric. Immediately to the 

 north and to the south of these Precambric ledges, Potsdam sand- 

 stone outcrops close to the fault on the upthrow side. Three- 

 foiif'ths of a mile south of these Precambric ledges the Theresa 

 formation is well shown on the upthrow side. 



This fault probably connects with the Sacandaga Park fault in 

 the depression north of Northville but the relations are wholly ob- 

 scured by drift. The amount of the dislocation at the southeast 

 edge of the village is probably about two hundred feet since the 

 lower dolomite is there faulted against the Precanibric. 



BUNKER HILL FAULT 



This fault, showing a strike of north 40° east, passes across the 

 top of Bunker hill and has its upthrow side on the east. Where it 

 crosses the road on the hill, Potsdam sandstone is exposed in a large 

 quarry and shows a dip of 10° toward the southeast. To the 

 east and south of the quarry no outcrops were found but the pas- 

 sage beds of the Theresa formation are thought to come in as shown 

 on the map. Within a few hundred yards to the west of the quarry 

 upper dolomite and Trenton limestone are exposed. Since the 

 Potsdam is brought up to the level of the Trenton, the amount 

 of displacement must be measured by the combined thickness of 

 the Little Falls and Theresa formations which here are approxi- 

 mately three hundred feet. This fault is probably only a south- 

 ward extension of the Northville fault but the utter lack of out- 

 crops across the river makes it impossible to positively connect 



