Report on the Geology of Orange County. 



By Heinrich Ries, Ph. D. 



Contents. Physical Geography, p. 395; Literature, p. 397. Straidgraphic Geology; Pre- 

 Cambriaii, p. 399; Cambrian, p. 400; Trenton, p. 400; Hudson River, p. 401; Me liua, p. 401; Helder- 

 berg, p. 401; Oriskany, p. 402; Esopus, p. 402; Onondaga, p. 403; Hamilton, p. 403; Chemung, p. 404; 

 Pleistocene, p. 405. Areal Geology: The Warwick Cambrian Limestones and the Granites, p. 405; 

 The Region along Bellvale Mouutain, p. 410; Area along Skunnemunk Mountain, p. 415; Relations 

 along the northwest of Skunnemunk Mountain, p. 418; The Region to the east and southeast of 

 Skunnemunk Mountain, p. 424; Area west of Cornwall, p. 426; Geology of Deer Park Township, 

 p. 428; Hudson River Shales and Sandstones, p. 439; The Neelytown Limestones, p. 442; Geology of 

 Newburgh and New Windsor Townships, p. 443; The Highland Area, p. 440; Dike Rocks, p. 457; 

 Pleistocene Deposits, p. 462. 



The following report is principally based on the results of three months' 

 work in the field during the summer of 1895, and to it is added such 

 additional information on the geology as has been published by others. 



Orange county is situated in southeastern New York, and extends from 

 the Hudson river on the east to a short distance beyond the Shawangunk 

 mountain on the west. The county has an area of 838 square miles, with an 

 east and west width of forty-five miles, and a north and south length of thirty- 

 five miles. On the east it is bounded by the Hudson river, on the north by 

 Ulster and Sullivan counties, on the west by Sullivan and Delaware counties, 

 and on the south by Pennsylvania and New Jersey.. The county is well 

 known on account of its scenery, mineral localities and dairy products. 



Topography. In the eastern portion of Orange count}', and bordering on 

 the Hudson river, are the Highlands, a range of parallel hills, nearly all of 

 them over 1,000 feet in altitude, and separated by shallow valleys. The more 

 prominent elevations of this region are : Crow's Nest, 1,418; Butler hill, 

 1,524; Bear mountain, 1,350 feet A. T. 



The Highlands cover about 140 square miles. 



West of the Highlands, and separated from them by a fault valley, is the 

 Bellvale-Skunnemunk ridge, extending in a northeasterly direction from the 

 state line, on the northwest side of Greenwood lake, to Cornwall. At 

 Monroe, the ridge is interrupted by a broad, transverse valley, and northeast 

 of Monroe it has a double crest with steep cliffs. 



The fertile rolling country to the northw est has a topography of little 

 variety, except to the south, the land gradually rising until it merges into the 



395 



