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NEW YORK STATE MUSEUM 



repeated by over-thrust faulting. Above the Becraft limestone 

 and below the beds pointed out by Mr Clark as " Upper Shaly," 

 and so mapped by Davis and Darton, the Coeymans limestone 

 was found in full force with characteristic Gypidula 

 g aleata and A t r y p a reticularis, as well as the 

 chert beds characterizing it as Becraft. Above the " Upper 

 Shaly.'' after careful search in the woods, the typical Becraft 

 limestone was found, which in turn was overlain by a darker, 

 fine grained limestone identical in character with the beds 

 lying between the Becraft and Oriskany at Becraft mountain. 

 Above this was found the Oriskany. On extending our observa- 

 tions, Mr Clark pointed out a spot where the Becraft, inclined 

 about 50°, was quarried below, and the Rondout waterlime, 

 inclined at 42°, was quarried above it. On examining the 

 contact between the limestones below the point where the 

 Coeymans was found overlying the Becraft, in the roof of an 

 old quarry in the latter rock, it was found that the line of 

 supposed overthrust was clearly marked by extensive slicken- 

 siding of the adjoining strata. 1 



A subsequent visit to this hill in company with Dr Ruedeinann 

 showed the essential correctness of the interpretation of the 

 structure, but it was found that the thickness of the beds lying 

 between the Becraft and the Oriskany was greater than at first 

 supposed. Dr Ruedemann measuring 110 feet. 



A visit to the section in the West Shore Railroad showed a 

 great thickness of the Upper Shaly beds between the Becraft and 

 the Oriskany. The section made by the railroad however is, as 

 pointed out by Mr Clark, a diagonal one and numerous small faults 

 occur in it so that the actual thickness would be less than 222 

 feet, as recorded by Clark. Since the interval between the Be- 

 craft and the Oriskany can be readily measured on Rondout hill, 

 though the beds occupying that interval are poorly exposed, it 



1 No " Upper Shaly " beds are recorded by Davis in his sections and descrip- 

 tions of the M Little mountain region " east of the Catskills. His map covers 

 an area of about 10 miles in length and throughout this the Oriskany, where 

 present, rests directly on the 120 feet of limestone which he referred to the 

 Upper Pentamerus (Becraft). The upper part of these undoubtedly represents 

 the Port Ewen of Becraft. 



