SANDSTONES 



383 



Sandstones are classified according to their geologic age also. 

 They are found occurring in all the series, from the oldest to the 

 most recent formations. Those of a given age are generally 

 marked by characteristic properties, which serve for their identi- 

 fication, aside from the fossil organic remains by which their 

 exact position in the geologic series is fixed. This persistence 

 in characters is exemplified in the Medina sandstones of the 

 State, in the Devonian bluestone of the Hudson River valley, and 

 in those of Triassic age. 



Sandstones occur in workable quantity in nearly all the 

 greater divisions of the State. 



Quarries have not, however, been opened everywhere in the 

 sandstone formations, because of the abundant supply of superior 

 stone from favorably situated localities. There are, in conse- 

 quence, large sandstone areas and districts in which there is an 

 absence of local development, or abandoned enterprises mark a 

 change in conditions, which has affected injuriously the quarry 

 industry in them. 



Following the geologic order of arrangement and beginning 

 with the Potsdam sandstone, the several sandstone formations 

 are here briefly reviewed. 



Potsdam Sandstone. 



This formation is the oldest in which, in this State, sandstone 

 is quarried for building purposes.* 



The bottom beds are a fine, silicious conglomerate ; above are 

 sandstones in thin beds generally. It is gray- white, yellow, 

 brown and red in color. In texture it varies from a strong, 

 compact quartzitic rock to a loosely coherent, coarse-granular 

 mass, which crumbles at the touch. 



Outcrops of limited area occur in Orange and Dutchess 

 counties, and in the Mohawk valley. In the Champlain valley 

 the formation is well developed at Fort Ann, Whitehall, Port 

 Henry and Keeseville, and quarries are opened at these localities. 

 The stone is a hard, quartzose rock, and in thin beds. North of 

 the Adirondacks the formation stretches westward from Lake 



* Some of the sandstones east of the Hudson and in the Taghkanic range may belong to the 

 Lower Cambrian. See Amer. Jour, of Science, iii series, vol. 35, pp. 399-401. But there &re no 

 quarries opened in these localities. 



