198 J. D. Dana—Age of the Green Mountains. 
west of Cocksackie. Mather describes another section on Pine 
Mountain, between Rondout and Kingston Point, where a high 
cliff of limestone overlies unconformably the gray grits of the 
Hudson slate series, the slates dipping 40° to 60° to the east- 
southeast, and the limestone 80° to the west-northwest. Other 
sections, from near Rondout, are given in the paper by Mr. T. 
Nelson Dale, in vol. xviii of this Journal (1879), p. 293. 
Special descriptions of the localities are not here necessary. 
From the observed facts it was inferred by Logan that a very 
extensive formation of Lower Helderberg limestone once 
ernine or mountain-making preceded the Niagara period, 
Ww 
* Third Series, vi, 339, 1873; and xiv, 379, 1877. 
