ECONOMIC GEOLOGY 199 



Crystalline limestones occur in New York and Westchester 

 counties, and in the Highlands of the Hudson. In the Adiron- 

 dack region there are numerous localities. The rock in many of 

 them is too impure and has too many foreign minerals to admit of 

 its use as marble. Quarries have been opened in Westchester, 

 Putnam and Dutchess counties, which have yielded a large 

 amount of fine white marble. In the northern part of the state, 

 the Port Henry and the Gouverneur quarries have been produc- 

 tive. The geological horizon of some of these marbles is in doubt. 

 The belt in the eastern part of Dutchess and Putnam counties 

 belongs to the Vermont marble range, and is probably metamor- 

 phosed Trenton limestone. The Westchester marbles are of the 

 same age. 



The limestones which furnish building stone in this state are 

 the Calciferous, Chazy, Birdseye, Black river, Trenton, Niagara, 

 Lower Helderberg, Upper Helderberg, or Corniferous, and Tully. 

 The geographical distribution is given in the following notes, and 

 in the order of geological succession, from the lowest to the 

 highest. 



Calciferous sandrock 

 The rocks of the Calciferous formation in the Mohawk valley 

 and in the Champlain valley are more silicious than at the south- 

 west, in Orange county and in the Hudson valley, and hence the 

 designation as a sandrock. Much of it at the north is a limestone 

 rather than a sandstone, and may be termed a magnesian or silicio- 

 magnesian limestone. Nearly all of the limestones, which are 

 quarried for building stone, in Orange and Dutchess counties are 

 from this formation. The stone occurs generally in thick and 

 regular beds. It is hard, strong and durable and is adapted for 

 heavy masonry as well as for fine cut work. The quarries near 

 Warwick, Mapes' Corners and near Newburgh in Orange county 

 and those on the Hudson river, near New Hamburg, are in the 

 Calciferous. The Sandy Hill quarry and those at Canajoharie 

 and Littlefalls are also in it. 



