SLATE 421 



SLATE 



Argillite or clay-slate, which is marked by the presence of 

 cleavage planes, and can be split into thin plates of uniform 

 thickness — roofing slate — is a characteristic rock in the Hudson 

 River group and the Lower Cambrian or Georgia group. 



Slate suitable for roofing has been found in many localities, 

 and quarries have been opened in Orange, Dutchess, Columbia, 

 Rensselaer and Washington counties. The openings in Orange 

 county have not resulted in productive quarries. In Columbia 

 county quarries were worked many years ago, east of New 

 Lebanon.* The Hoosick quarries, in Rensselaer county, were 

 more extensively worked, and produced a good, black slate. 

 Outcrops of red slate are noted east of the Hudson, from Fishkill 

 and Matteawan northward, but no attempts have been made to 

 open quarries in them. 



The productive slate quarries of the State are in a narrow belt, 

 which runs a north-northeast course through the towns of Salem, 

 Hebron, Granville, Hampton and Whitehall, in Washington 

 county. 



This slate belt is divided by the quarrymen into four parallel 

 ranges or " veins," which are : East Whitehall red slates ; the 

 Mettowee, or North Bend red slate; the purple, green and varie- 

 gated slates of Middle Granville ; and the Granville red slates. 

 The latter is close to the Vermont line. Further to the east, 

 but over the State line, in Yermont, is the range of the sea-green 

 slates. 



The quarry localities are at Shushan, Salem, Black Creek 

 valley, in the town of Salem, Slateville, in Hebron, Granville, the 

 Penrhyn Slate Company's quarries, Middle Granville, Mettowee 

 or North Bend quarries, and the Hatch Hill quarries in East 

 Whitehall. 



The quarries of Washington county have not yet been worked 

 down to as great depth as some of those in Northampton and 

 Lehigh counties, in Pennsylvania, and the deepest has not reached 

 a vertical depth of 100 feet. 



Tho quarries at the southwest, in Shushan and Salem, produce 

 purple, variegated and green-colored slates. At Salem some 



* Wm, W. Mather, tfeology of the First Geological District, Albany, 1843, pages 419-421. 



