296 H. p. GUSHING — FAULTS OF CHAZY TOWNSHIP, NEW YORK. 



that in the township next south a precisely similar fault (B-B) hides the 

 entire Chazy limestone from view throughout the township, though it 

 reappears again in the next town beyond in the same strength which it 

 exhibits in Chazy township. 



Conclusions. 



In the rocks of Ordovician age occurring along lake Champlain the 

 detection of faults is not a matter of great difficulty, but back from the 

 lake in New York the criteria which avail for their determination in the 

 Ordovician rocks are not furnished by the older Cambrian and pre- 

 Cambrian strata.* Yet that both are much faulted is certain. 



It has just been shown that a large proportion of the contacts between 

 rocks of different age in Chazy township are fault-contacts, and the same 

 may be shown with equal readiness in most other townships on either 

 side of lake Champlain. It is believed that this will be found to be 

 true also in the Adirondacks themselves, but their discrimination from 

 ordinary deposition-contacts will be extremely difficult. As an illustra- 

 tion : Wherever in Clinton county the writer has found demonstrable 

 deposition-contacts between the Potsdam and the older rocks a basal 

 conglomerate or an arkose or both are shown. Where these are absent 

 the relations are often such as to strongly suggest contact by faulting. 

 At other times no indications whatever of the character of the contact 

 are afforded. That the crystalline rocks of the Adirondacks are also 

 faulted can be often shown by means of the numerous dikes and of the 

 beds of iron ore. The topography is often such as to strongly suggest 

 faulting. Certainly the possible presence of faults must be constantly 

 kept in mind when endeavoring to interpret the stratigraphy of that re- 

 gion, and the main purpose of this paper is to emphasize this fact, in 

 view of the work now being prosecuted there. 



*The term pre-Cambrian is preferred at present for these rocks, as it is purely non-committal. 



