LIME AND CEMENT INDUSTRIES 821 



Of these the Becraft and the cement beds are the most im- 

 portant. 



Onondaga limestone has been quarried at a number of locali- 

 ties for burning into lime. The stone is generally light blue 

 gray, dense and massive. Unfortunately a common feature is 

 the presence of layers of chert, though these may be locally ab- 

 sent. They predominate chiefly in the upper beds. 



Darton states 1 that the outcrop of the Onondaga limestone is 

 practically continuous from the northeastern corner of the county 

 to Wawarsing township. Around Kingston its area widens 

 greatly, on account of the presence of folds, and most of the 

 upper part of the city is built on it. Southward by Hurley and 

 Marbletown the Onondaga formation is prominent in the ridge 

 sloping westward to Esopus creek. Exposures also abound along 

 the West Shore railroad northward from Kingston, and, from 

 west of Saugerties to Asbury, along and near the road passing 

 through Cedar Grove and Katsbaan. 



Through its whole extent the upper shaly limestone exhibits 

 a large amount of argillaceous and silicious impurities. The beds 

 are massive, but the rocks possess a slaty cleavage, and these 

 properties aid in the formation by them of small rough ridges. 



It extends across the county parallel with the Onondaga lime- 

 stone. As far as known, it is not available for anv of the uses 

 treated of in this report. The upper shaly overlies the Becraft 

 limestone. 



In Ulster county the Becraft is the purest limestone of the whole 

 Lower Helderberg series. The beds are massive, bluish gray to 

 reddish limestone, of a semicrystalline nature and highly fossil- 

 iferous. Scattered through the rock are saucer-shaped masses 

 of white, crystallized lime carbonate, from 1 to 2 inches in diam- 

 eter and representing the bases of crinoid heads. The formation 

 according to Darton varies from 20 to 30 feet in thickness. 



1 Geology of Ulster county, (see 13th an. rep't N. Y. state geol. p. 301) 



