descriptive notes op^ quarry districts and quarries 279 



Slate 



Argillyte or clay-slate, which Is marked by the presence 

 of cleavage planes, and can be split into thin plates of uni- 

 form thickness — roofing-slate — is a characteristic rock in 

 the Hudson river group, or Hudson terrane. Shales, 

 sandstones and fine siliceous conglomerates are often asso- 

 ciated with the slates. 



The formation occupies the valley of the Wallkill, in 

 Orange county, the Hudson-Champlain valley, from the 

 Highlands north to Lake Champlain, and the Mohawk val- 

 ley and a belt west and north-west, to Lake Ontario. 



Slate suitable for roofing has been found in many locali- 

 ties, 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 Fishklll and Matteawan 

 northward, but no attempts have been made to open quar- 

 ries In them. 



The productive slate quarries of the state are in a nar- 

 row belt, which runs a north-north-east course through the 

 towns of Salem, Hebron, Granville, Hampton and White- 

 hall, 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 variegated 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 Ver- 

 mont, Is the range of the sea-green slates. 



*Wm. W. Mather, Geology of the First Geological District, Albany, 1843, pages 

 419-421. 



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