782 NEW YORK STATE MUSEUM 



Three distinct areas of Cliazy and Trenton limestones occur 

 in this connty. The first forms Willsboro point and extends 

 southward as far as Whallonsburg. A second area begins at 

 Westport and extends southward to the town of that name. A 

 third is on Larrabees point. 



The Black river limestone member of the Trenton is usually 

 heavy bedded, very tough and compact. The rock has beeu 

 quarried on Crown point. 



The Trenton proper, also exposed on Crowu point, is 150 feet 

 thick, but is usually thin bedded, showing alternations of liirie- 

 stone and shale layers. The Trenton has been used at several 

 places for making lime, but no definite statement can be made 

 concerning the purity of any given beds, as they are variable. 

 At times the rock is quite low in silica. Large quarries have 

 been opened on Willsboro point (pi. 38), and in the town of Es- 

 sex, and the stone from the former vras shipped to 'New York city. 



A partial analysis of the Chazy limestone on Willsboro point, 

 furnished the writer by Prof. J. F. Kemp, showed: 



Lime 51 



Magnesia 1 



Silica 2.43 



The following represent the average composition of 1) the 

 upper 10 feet and 2) the lower 10 feet of the quarry from anal- 

 yses made of samples collected by the writer. 



1 8 



Silica 4.4 4.6 



Alumina Yd 4.1 



Ferric oxid 3.5 1.9 



Lime carbonate Y9 . 2 87.7 



Magnesium carbonate 4.2 .98 



Insoluble 15 12 . 6 



Water ^ 2 



The following additional ones are given by T. G. White.-* 



1 Lower beds of quarry on Willsboro point. 



If Geology of Essex and Willsboro townships, Essex co., N. Y. {see Trans. 

 N. y. acad. sei. 13: 214-31) 



