ECONOMIC GEOLOG-Y 187 



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, in the 

 Devonian Milestone, 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 injuriously affected the quarry 

 industry. j ; 



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 of fine, silicious conglomerate; above are 

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

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

 pact quartzite rock to a loosely coherent, coarse-granular mass, 

 which crumbles at the touch. 



Outcrops of limited area occur 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 Champlain to the St Lawrence; and there 

 are quarries in the towns of Malone, Bangor and Moira in Frank- 

 lin county; in Potsdam and Hammond in St Lawrence county; 



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

 to the Lower Cambrian. See Amer. Jour, of Science, series iii, vol. 35, pp. 399-401. 

 But there are no quarries opened in these localities. 



