Ries — Geology of Orange County. 



397 



lake is the largest in the county, being six miles long and three-quarters of 

 a mile wide, but only half of it lies within the state. 



Many of the lakes are disappearing, on account of swamp-growth 

 extending from their inlets, or the cutting down of their outlets, and the beds 

 of former ponds are an important agricultural feature of the county. 



The geologic formations occurring in the county range in age from the 

 Pre-Cambrian to the upper Devonian. Nearly two-thirds of the county is 

 underlaid by the Hudson river slates, as will be seen from the accompanying 

 geologic map, and the crystalline rocks of the southeastern portion also cover 

 a considerable area. The other formations occur in irregularly shaped areas 

 of variable size, but there is a tendency in them all to extend in a northeast 

 and southwest direction. 



Folding and faulting have produced numerous and local complications, 

 especially along the line of Bellvale and Skunnemunk mountains. 



The following bibliography indicates what has already been published 

 on the geology of Orange county : 



Barrett, S. T., 1876 : Notes on Lower Helderbe'rg rocks of Port Jervis, N. Y., 

 and descriptions of a new Pteropod. Ann. N. Y. Lye. Nat. Hist., Vol. 

 XL, p. 290. 



Barrett, S. T., 1877 : The Lower Helderberg rocks of Port Jervis, N. Y. 



A. J. S. (3), XIII., p. 385. 

 Barrett, S. T., 1878 : The Coralline or Niagara Limestone of the Appalachian 



system. A. J. S. (3), XV., p. 370. 

 Barrett, S. T., 1878: Descriptions of new species of Fossils from the Upper 



Silurian rocks at Port Jervis, N. Y., with notes on the occurrence of the 



Coralline Limestone at that locality. Ann. X. Y. Acad. Set., I., p. 121. 

 Darton, N. H., 1884 : Preliminary Notes on Fossils in the Hudson River 



Slates of the southern part of Orange county, N. Y. A. J. K (3), 



XXX., p. 452. 



Darton, N. H., 1886: On an area of upper Silurian rocks near Cornwall, 



eastern central Orange county, N. Y. A. J. S. ( 3), XXXI., p. 209. 

 Darton, N. H., 1885: Gives review of geologic relations from Green pond to 



Skunnemunk mountains. Sci. Amer. Sup., XIX., p. 7,877. 

 Darton, N. H., 1885 : The geologic relations from Green pond, N. J., to 



Skunnemunk mountain, N. Y. Bull. Qeol. Soo. Amer., V., p. 367. 

 Dwight, W. B., 1880: Calciferous as well as Trenton Fossils in the Wap- 



pinger Limestone at Rochdale, and a Trenton locality at Newburgh, 



N. Y. A. J. S. (3), XIX., p. 50. 



