38 NEW YORK STATE AIUSEUM 



FRANKFORT SHALE 



The Frankfort formation is represented by a single small area 

 on the geologic map and this at the extreme southeast corner where 

 it is sharply faulted against the Little Falls dolomite. The forma- 

 tion consists of alternating thin beds of shale and sandstone, the 

 shale bearing a close resemblance to the Utica and the safidstone 

 layers being dark gray, fine grained and weathering to yellowish- 

 brown. A yellow sandy clay soil is characteristic of the Frankfort 

 area. There is no sharp line of demarkation between the Utica 

 and Frankfort but, in passing upward, the beginning of the sandy 

 layers is taken to mark the base of the Frankfort. Doctor Ruede- 

 mann states, in a letter to the writer, that the Frankfort which 

 shows a thickness of about three hundred feet at its type locality 

 swells to a thickness of fifteen hundred feet or over in the lower 

 Mohawk valley. 



FAULTS 

 The Broadalbin quadrangle is of unusual interest because of the 

 number of well-defined faults. They belong to the well-known 

 series of the Mohawk valley although several of the faults within 

 the quadrangle are here described for the first time. All are of 

 the normal or gravity type with displacements usually ranging from 

 about one hundred feet to over fifteen hundred feet. So far as 

 can be determined the hade is always very steep if not vertical and 

 with but two or three exceptions the strike is north-northeast. 

 The topography of the district is largely dependent upon the fault- 

 ing. The age of the faults is not precisely known but they are 

 usually considered to have been formed during the great Appa- 

 lachian revolution which so profoundly affected the physiography 

 of the eastern United States, producing the Appalachian mountains 

 and causing a general uplift, above sea level, of the Paleozoic sedi- 

 ments in New York State. 



THE NOSES FAULT 



From the standpoint of both length and amount of displacement 

 this is one of the two greatest Mohawk valley faults. Where it 

 crosses the Mohawk river, near Yosts or about five miles below 

 Canajoharie, a picturesque gorge has been cut through the uplifted 

 Little Falls dolomite. The sharp high cliffs along the fault and 

 on opposite sides of the river have given rise to the name " Noses." 

 According to the measurements of Prosser and Cumings^ the thick- 



1 15th An. Rept. N. Y. State Geologist, p. 643-44. 



