LIME A^B CEMENT INDUSTRIES Y53 



GEOLOGY OF ISTEW YOKK LIMESTOISTES 



Limestones are found in 'Ne^Y York from the oldest to tlie 

 youngest formations. Some, like tliose of tlie pre-Cambrian, are 

 often local in tlieir extent; while others, like those of the Helder- 

 berg, extend from one end of the state to the other. 



The formations containing limestone in ISTew York state are 

 the pre-Cambrian, Calciferons, Chazy, Trenton, Clinton, Niagara, 

 Onondaga, Lower Helderberg, Upper Helderberg, Goniatite, 

 TuUy, Quaternary marls. 



The most important of these are the Calciferons, Trenton, 

 ISTiagara, Lower Helderberg and Upper Helderberg. The Calcif- 

 erons and I^iagara sometimes contain sufficient magnesia to be 

 called true dolomites, and this fact, together with the freedom 

 from impurities which they exhibit at some localities, gives them 

 a special usefulness, 



Calciferons 



The rock of this formation is frequently highly magnesian, 

 and a high percentage of silica is likewise not uncommon in it. 

 On this account it is sometimes called Calciferons sandrock. 



The Calciferons limestones occur as isolated patches or belts 

 in several parts of the state, and show considerable variation in 

 character. With few exceptions they are magnesian and indeed 

 may pass into true dolomites. - On the other hand, they are often 

 highly silicious, so much so as to render them practically worth- 

 less for any of. the uses considered in this report. Again they 

 may run very low in silica, as near Glens Falls. 



Cambro-Silurian limestones appear in the southeastern portion 

 of the state in Orange county, extending northeastward across 

 the countv to the Hudson river, and across it throusrh Dutchess 

 into Columbia county. 



Another series of belts begins in Westchester county and ex- 

 tends from ISTew York city northward to the county line and 

 through Putnam and Dutchess counties to Pawling and beyond. 



