THE MINING AND QUARRY INDUSTRY I915 7I 



building stone, rough and dressed, accounted for $6i,6oi and monu- 

 mental for $37,074 against $142,223 and $70,797 respectively in 

 1914. Other kinds of marble quarried had a value of $21,772 

 against $iy,222 in 1914. 



SANDSTONES 



• Under sandstones are included the sedimentary rocks v^^hich 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 sandstone at one or 

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

 son River, Medina and 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 Potsdam 

 and Redwood, St Lawrence county, and Malone and Burke, Frank- 

 lin county. Besides building stone, which is the chief product, there 

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

 ment to Montreal. 



The so-called Hudson River group is essentially a group 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 actual delimitation of the various members on 

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



