GEOLOGY OF THE REMSEN QUADRANGLE 



27 



writer of the thickness of the upturned strata from the base of the 

 coarse crystalline beds to the crushed zone at the creek level near 

 the fault plane gave 140 feet. This result corresponds to within a 

 few feet of the thickness obtained by Prosser and Cumin gs for the 

 same set of strata farther down the gorge. According to those 

 authors the conspicuously contorted stratum opposite the top of 

 the lower fall of High fall occurs just above their zone A 5 or 144 

 feet below the top of the Trenton. This same contorted stratum 

 has been traced by the writer to near the fault and between it and 

 the fault there intervenes a thickness of 2 5 or 30 feet of still lower 

 strata. It is evident therefore that the beds as low at least as the 

 upper part of Prosser and Cumings zone A 5 are thrown by faulting 

 against the gray crystalline upper Trenton beds. Thus the strati- 

 graphic throw of the fault (disregarding the crushed zone) is some- 

 thing like 140 feet. The throw or vertical displacement is prob- 

 ably from 30 to 50 feet greater than the stratigraphic throw. Be- 

 cause of the high angle of dip of the fault plane the heave (hori- 

 zontal displacement) must be considerably less than the throw. 



Upturned strata are often present among the shales on the 

 downthrow sides of the Mohawk valley faults. They are due to an 

 updragging effect produced by normal faulting. At the Trenton 

 fault, however, the strata are upturned on the upthrow side and 

 were bent upward by the lateral pressure which first probably de- 

 veloped a fold and later a fracture so that the middle Trenton rocks 

 were pushed upon the upper Trenton. 



Where the fault line would be expected to cross the creek about 

 J of a mile eastward the only sign of disturbance is a small but 

 very distinct fold in the limestone beds. Thus the fault above 

 described dies out so rapidly that within the \ mile it is entirely 

 gone and passes into a small fold. Beyond this the line of dis- 

 turbance can not be traced because of heavy drift deposits. 



Minor faults. A number of small faults have been noted along 

 the gorge between High fall and Prospect but the throw is always 

 slight. The Trenton rocks have been considerably disturbed by 

 folding and faulting on Mill creek and one of its tributaries about 

 a mile above Gravesville. Sharp folding is well shown where the 

 line crosses Mill creek (at the mill), while folding accompanied by 

 faulting of unknown though small extent is exhibited where the 

 line crosses the tributary (the second one above Gravesville) a 

 quarter of a mile above its mouth. This line of disturbance strikes 

 n. 70 w. and it can not be traced across country. 



