432 NEW YORK STATE MUSEUM 



has resistant Potsdam on one side as againsit weak limestones 

 on the other. Farther southwest, however, where it passes into 

 higher ground, the prominent east face of Rand hill is its scarp. 

 So far as these low altitude faults are concerned, they give no 

 evidence of recent faulting. 



Some slight relief has been produced along some of the small 

 cross faults^, in cases where the dip iS' fairly high, 10° or more. 

 These are dip faults; and, since the limestonesi which they croiss 

 have slightly variant resisting power, the more massive beds 

 srtand slightly above the surface as ridges, and their lateral 

 shifting by the fault is clearly brought out in the topography. 

 The Black river limestone, and some of the beds of the Grown 

 Point division of the Chazy, are the more prominent ridge makers 

 of thisi type. This topography is very characteristic of the 

 cross-faulted strip ,shown in plate 12. 



The drainage is not so independent of the faults in this district 

 as it is along the Mohawk. Many of the istreams follow the fault 

 lines for considerable distanoesi, T'racy brook and' the Little 

 Chazy river, as shown in plate 12, for example. 



It is however in this eastern district that the evidence of recent 

 faulting is forthcoming. In the rapid rise in altitude from the 

 Champlain level to the main axis of elevation, which is from 

 25 miles to 30 milgs west from the lake only, are many eastward 

 facing cliffs which resemble fault scarps. The larger number 

 of these show equiresistant rock on both sides. Thus there are 

 apparent faults which are wholly in the Potsdam, having that 

 rock on both sides and with no detectable difference in the resist- 

 ance, which, notwithstanding, present a prominent easterly cliff. 

 Wear, because of renewed uplift, could by no possibility have 

 brought out this topographic relief; and, in the total absence 

 of evidence of any other mode of origin, a belief that they are 

 fault scarps is compelled, necessitating the further belief that 

 they can be no older than the date of uplift of the Cretaceous 

 base level, and may perhaps be younger. 



The majority of the supposed faults are in Precambric rocks. 

 In many cases there seems little difference in resisting capacity 

 of the rocks on the two sides, and in certain cases the rock is 



