Ries — Geology of Orange County. 



399 



White, T. C, 1882: Various references to Orange Co. in Rep. G(>, Penn. 

 Greol. Sui'v. 



Whitfield, R. P., 187V): Discovery of specimens of Mucin red- magna of the 

 Chazy, near Newbnrgh, N. Y. A. J. S. (3), XVIII., p. 227. 



Williams, G. II.: On some remarkable crystals of pyroxene from Orange 

 Co., N. Y. 



Ward, L. F., Notes occurrence of plants at Woodbury Falls. 8th Ann. /?<'/>., 

 U. S. <}. S., p. 859. 

 Of the above list of papers the more important are those of Prof. Kemp 

 and Mr. Hollick, Prof. Prosser and Mi'. Darton. 



The following is a list of the formations occurring in Orange county, 

 together with their character and approximate thickness : 



Pre-Cambrian, 



Gneisses, granites and limestones, 





Olenellus, ? 



Limestones, usually impure, 



20' + 



Cambrian, 



Limestones, 



200 + 



Trenton, 



Limestones, 





Hudson river, 



Shales, slates and sandstones, 



2,000 + i 



Medina (inch Oneida), Sandstones and conglomerates, 



150-750' 



Lower Helderberg, 



Limestones and shaly limestones, 



25-500' 



Ori'skany, 



Impure limestones, sandstones, 







quartzite and conglomerate, 



50-150' 



Ks< >pus, 



Slates and sandstones. 



750'± 



Onondaga, 



Cherty limestones, 



250' 



Marcellus, 



Arenaceous shales and shah' sandstones, 800' 



Hamilton, 



Shales, sandstones, flagstones and 







conglomerates, 



1,200-1,800' 



Chemung, 



Arenaceous shales and sandstones, 



2,250' 



Pleistocene, 



Clays, sand, gravel and boulders, 





tE- Cambrian. This 



formation consists of a <j-reat mass 



of gneisses. 



gneissic rocks, and some limestones. At times the gneissic ro< ks are massive 

 and resemble a true granite. At other localities they present a schistose 

 facies. These rocks form the Highland region, the northwestern side of 

 Bellvale mountain, and a series of rounded knobdike hills extending from 

 Sugar Loaf village to Newburgh. 



The gneiss is usually a mixture of quartz, biotite and feldspar, the latter 

 often plagioclase. Hornblende sometimes predominates, as in the gneiss of 

 Bellvale mountain and Tuxedo township. Pyroxene gneisses also occur. The 



