Ries — Geolooy of Ouanok County. 



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Pleistocene. These deposits are represented by the usu;d accumulations 

 of gravel, sand and boulders. In the larger valleys, as those of the Neversink. 

 Shawangunk, and Wallkill rivers, the gravel and sand accumulations are of 

 great extent and depth. Those of the Neversink valley are in places know n 

 to be over one hundred feet thick. Large boulders are restricted to New- 

 burgh, Cornwall and Tuxedo townships, in which they are quite abundant. 

 The alluvial deposits are represented by terraces along the Hudson river and 

 other streams and by numerous pleistocene lake beds which cover some 

 40,000 acres. The pleistocene deposits are mentioned in detail hereafter. 



Geology of the Warwick Cambrian Limestones and the Granites. 



In the south-central part of Orange county is a belt of blue and white 

 limestone which begins about two miles southwest of Goshen, in Goshen 

 tow nship and, extending through the western part of Warwick township 

 with increasing width, passes on continuously for twenty miles into New 

 Jersey. To the east of the Drowned Lands, and opposite Black Walnut 

 Island, the belt is about two and one-half miles wide, and continues this width 

 to Amity, where it narrows to two miles. A branch of the blue limestone 

 extends from this point to the northeast, and will be described hereafter. 

 The limestones also extend under the Drowned Lands, and the blue limestone 

 is found again on the west side, where it passes under the Hudson river 

 slate. The white limestone occurs only in the main central belt, and is there 

 closely associated with the blue. The area occupied by each can best be 

 apprehended by an examination of the map. In Orange county no fossils 

 have been found in the limestone, but the contained remains found in New- 

 Jersey prove it to be of Cambrian age. The white limestone surrounds two 

 areas of granite and gneissic rocks, and borders on a third, Pochuck moun- 

 tain. It is also penetrated by many granite dikes and masses containing 

 contact minerals. 



Several opinions have been advanced regarding the age of the blue and 

 the white limestones. Keating and Vanuxem [>T<>ur. Phila. Acad. Sci., 1822, 

 p. 277); C. U. Shepard (A. J. S. i-XXI., p. 323) 5 ; Cook (1868, Geo!. X. J.. 

 p. 310); and Britton (JY. J. Qedl. Sim)., 1886, p. 77-83), considered that the 

 white crystalline limestone was of Archean age, deposited on the gneisses and 

 granites, and metamorphosed. The blue limestone was considered Cambrian. 



On the other hand, Nuttall (A. J. K TV., p. 247), Rogers (K J. Geol. 

 Snrr., 1840, p. 47-67), Nason (JSF.J. Geol. Surv., 1890, p. 25-50), and Mather 

 consider that the blue and the white limestones are one and the same fornia- 



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