40 NEW YORK STATE MUSEUM 



during the earlier period of its history was in a flourishing state 

 as the product found a wide sale for the grinding of cereals. This 

 market has been greatly curtailed within the last quarter of a 

 century or more by the general use of the roller mill process for 

 making flour, although some mills still, make use of stones for 

 grinding the coarse grains. The small corn mills in the South 

 furnish one of the larger markets for the New York product. Be- 

 sides millstones, the Ulster county quarries also turn out disks of 

 stone known as chasers which are employed in a roll type of 

 crusher, the disks revolving on a horizontal axis in a circular pan 

 that is sometimes floored by blocks of the same stone. This type 

 of crusher is much used in the grinding of minerals like quartz, 

 barytes and feldspar, and paint materials. 



The Shawangunk grit of which the stones are made outcrops on 

 Shawangunk mountain, a monoclinal ridge that extends from Rosen- 

 dale southwesterly into New Jersey and Pennsylvania. The grit 

 forms the top of the ridge, dipping to the west in conformity with 

 the slope of the surface, -and in the Walkill valley along the north 

 side disappears below shales and limestones which belong to the 

 uppermost formations of the Siluric. The grit rests unconform- 

 ably upon the Hudson River series. In thickness it ranges from 

 50 to 200 feet. The millstones are quarried within a limited section 

 of the ridge, between High Falls on the north and Kerhonkson on 

 the south, where the grit appears to be best adapted to the purpose. 

 In character it is a light gray conglomerate with pebbles of milky 

 quartz ranging in size from that of a pea to 2 inches in diameter. 

 The pebbles are rounded and firmly cemented by a silicious matrix 

 of gritty texture. 



The work of quarrying requires only a small equipment, the stone 

 being pried out by hand bars, after the use perhaps of the drill and 

 plugs and feathers. Sometimes a little powder may be employed, 

 but care has to be exercised in its use to avoid weakening the stone. 

 The spacing of the natural joints determines the size of the stone 

 that may be produced, the joints occurring in two sets approxi- 

 mately parallel to the dip and strike of the formation. The rough 

 blocks thus obtained are reduced to shape by the hammer and point 

 and then undergo a final tool dressing which varies with the use 

 to which the stone is to be put. The hole or " eye " in. the center is 

 drilled by hand. 



The sizes of the stone marketed ranges from 15 to 90 inches in 

 diameter. The greater demand is for the smaller and medium 

 sizes with diameters of 24, 30, 36, 42 and 48 inches. The chasers 



