86 NEW YORK STATE MUSEUM 



SANDSTOXK 



Under sandstone are included the sedimentary rocks which con- 

 sist essentially of quartz grains held together by some cementing 

 substance. Among the varieties distinguished by textural features 

 are sandstones proper, conglomerates, grits and quartzites. 



Of the sedimentary rocks which occur in the State, sandstone 

 has the largest areal distribution, while in economic importance it 

 ranks second only to limestone. Nearly all the recognized strati- 

 graphic divisions above the Archean contain sandstones at one or 

 more horizons. The kinds chiefly quarried are the Potsdam, Hud- 

 son River, Medina and the Devonic sandstones. A few quarries 

 have been opened also in the Shawangunk conglomerate and the 

 Clinton and Triassic sandstones. 



The Potsdam of the upper Cambric is the lowest and earliest in 

 age of the sandstones that have a fairly wide distribution and are 

 utilized for building purposes. The most extensive outcrops are 

 along the northern and northwestern borders of the Adirondacks 

 in Clinton, Franklin, St Lawrence and Jefferson counties. Other 

 exposures of smaller extent are found in the Lake Champlain 

 valley and on the southeastern edge of the Adirondack region. 

 These latter areas represent the remnants of a once continuous belt 

 that has been broken up by folding, faulting and erosion. The 

 Potsdam sandstone has in many places the character of a quartzite, 

 consisting of quartz grains cemented by a secondary deposition of 

 quartz, and then is a very hard, tough and durable stone. The 

 quartzite from St Lawrence county has sustained a crushing test of 

 more than 42,000 pounds to the square inch. The color varies from 

 deep red to pink and white. The principal quarries are near Pots- 

 dam and Redwood. St Lawrence county, and Malone and Burke, 

 Franklin county. P>esides building stone which is the chief product, 

 there is some flagstone sold, mainly by the quarries at Burke for 

 shipment to Montreal. 



The so-called Hudson River group is essentially a series of sand- 

 stones, shales, slates and conglomerates, ranging in age from the 

 Trenton to the Lorraine, but which have not been sufficiently 

 studied to permit the accurate delimitation of the various members 

 on the map. The group is exposed in a wide belt along the Hudson 

 from Glens Falls southward into Orange county and also in the 

 Mohawk valley as far west as Rome. The sandstone beds are 

 usually line grained, of grayish color and rather thinly bedded. 

 Over wide stretches they provide practically the only resource in 



