GEOLOGY OF THE NORTH CREEK QUADRANGLE 53 



Strikes. The usual evidences prove the faulting, the eastward 

 downtilt of the fault block being especially well shown. Neither 

 of the two faults just described has a maximum displacement of 

 more than a few hundred feet. 



Brant lake faults. A very prominent fault, which may be called 

 the Brant lake fault, passes along the northern side of the lake of 

 the same name within the adjoining Bolton sheet. The lake clearly 

 occupies a depression at the base of this fault scarp. Only the 

 western end of this fault comes into the North Creek quadrangle 

 w^here it passes along the southern base of the mountain at the 

 village of Horicon. It can not be traced across the Schroon river. 

 Near the village of Horicon distinctly sheared and slickensided rock 

 may be seen in the granite quarry. At the village the displacement 

 appears to be no less than 400 or 500 feet. 



On the south side of the narrow valley at Horicon a smaller 

 fault, parallel to the larger one, is clearly indicated by a crushed 

 zone in the granitic syenite. The eastward extent of this fault is 

 not knov/n. 



Chestertown faults. A prominent fault with northwest-south- 

 east strike lies along the southwestern l^ase of Prospect mountain 

 and is thought to be continuous with the fault shown on the map 

 just east of Loon lake. These two are certainly exactly in line 

 and, though they have not been positively connected, they will be 

 regarded as parts of the same line of fracture. At the Loon lake 

 end the fault shows an almost vertical scarp 300 feet high where 

 it passes along the western border of the gabl^ro stock. The scarp 

 there consists of badly sheared gabbro, and Grenville limestone 

 dips directly against the base of the scarp. The southwestern side 

 of Prospect mountain is a fine example of a high, steep fault scarp 

 with banded Grenville gneisses dipping eastward against the base of 

 the mountain which consists of a granitelike mass of gneiss. A 

 displacement of no less than 700 feet is shown here. The southern 

 end of the fault is marked by a rather steep scarp several hundred 

 feet high and in the homogeneous granite porphyry. 



There is fairly good reason to think that another fault with 

 north-south strike passes through the western edge of the village of 

 Chestertown, but since its presence is not certain it is represented 

 on the map by a broken line. The fairly prominent scarp which 

 forms a long straight boundary between the Grenville and the 

 igneous rocks is the chief evidence for considering a fault here. 

 The fault plane is mostly concealed by heavy drift. 



