Ries — Geology of Orange County. 



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obscure bedding. No fossils have been found in these rocks in Deer Park 

 township. 



Excellent exposures of the black Esopus slate are to be seen in the 

 railroad cut of the New York, Lake Erie & Western railroad, about a mile 

 and one-half northeast of Port Jervis. The formation crosses the Neversink 

 river above Port Jervis and disappears under the drift of the valley. 



Onondaga (Corntferotts) Limestone. The beds of this age are repre- 

 sented by a dark grey limestone in layers one to ten inches thick, and 

 containing numerous black chert nodules of an irregularly elliptical shape, 

 whose longer diameter is sometimes a foot. The limestone forms Carpenter's 

 Point, near Port Jervis, in the southeastern part of Deer Park township, and 

 also outcrops in a small area farther up the valley, near Port Orange. 



Weathering dissolves the lime carbonate, and often leaves the masses 

 of chert projecting several inches above the surface. The nodules sometimes 

 contain fossils (I. C. White, Pennsylvania Geological Survey, G. 6). The 

 Corniferous limestone dips gently to the west. The thickness can not be 

 determined from the exposures at Carpenter's Point, but White estimates it 

 at 250 feet. 



Hamilton Group. This is an important formation in Orange county. 

 The lower member, the Marcellus shale, consists of a series of dark colored, 

 bluish black or brown, arenaceous shales, which crop out along the western 

 side of the Neversink valley. They are fossiliferous at several localities, 

 notably at Port Jervis and Rose Point, eight miles northeast of it. They 

 have a low western dip and a steep easterly dipping cleavage. Their thick- 

 ness, which is in part buried by the drift of Neversink valley, has been 

 estimated by White* and also by Prosser at 800 feet, which seems very 

 probable. 



The upper member, or Hamilton proper, overlies the Marcellus, but is 

 not separated from it by any sharp line of demarkation. It forms a series 

 of arenaceous shales and shaly sandstones in its lower beds, while the upper 

 ones are thinly laminated sandstones. The lower members contain abundant 

 fossils. The total thickness in Deer Park township is about 1,800 feet, 



The second area of Hamilton rocks forms the greater portion of Bell vale 

 and Skunnemunk mountains, and has been divided by Dartonf into three 

 members, viz.: the Monroe shales, Bellvale flags and Skunneninnk con- 

 glomerate. £ 



* Report G 6, Pennsylvania Geological Survey. 



t The Devonian of Eastern New York and Pennsvlvania. Bulletin United Stales Geological Survey. No. 120, 

 : Bulletin Geological Society of America, V , p. 367. 



