OP STRATA. 



35 



t^LASs 11. Transition or Second Series. 



7. Akgillite, is a slate rock of an aluminous character, .2. Carbo- 

 niferous for- 



and nearly homogeneous, always consisting of tables or lammse nmtion. 

 whose direction forms a large angle with the general direction 

 of the rock. Subdivisions. Claij Slate, when the argillite is 

 nearly destitute of all grittiness, and contains no scales of mi- 

 ca or talc. Wacke Slate, when it is somewhat gritty and con- 

 tains glimmering scales of mica or talc. Varieties. Roof 

 Slate, when the slate is susceptible of division into pieces suit- 

 able for roofing houses and for cyphering slate. Glazed Slate, 

 when the natural cleavages are lined with a black glazing. — 

 This variety contains anthracite coal and marine animal relics, 

 and ferns.* 



Localities. Clay Slate, Williamstown Mountain Hange, 

 the bed and banks of the Hudson. Wacke Slate, overlying 

 the clay slate, most of the way from Massachusetts line to three 

 miles west of Cohoes Falls, in New- York. As this slate takes 

 the same inclination with the clay slate, and difiers widely from 

 the horizontal (or 1st) gray wacke, and as their meeting can 

 never be ascertained, I have presumed to join them. Varie- 

 ties. Chloritic. Both of the divisions are often coloured green 

 by the chlorite in Rensselaer county. Roof Slate. That 

 which splits freely into roofing slate, Hoosick, Chatham, N. 

 Y., Water Gap of Delaware River, Pa. Glazed Slate, banks 

 and beds of the Hudson from Fort Miller to near Newburgh, 

 Water Gap of the Delaware. CMoritic, red ^nA purple, vdiVi- 

 eties frequently occur near its junction with the primitive rocks. 

 Contents. Silicious Slate, nearly black, and of different 

 shades of green, in the glazed variety at Troy and a few miles 

 below Albany, in extensive beds. Basanite, in the glazed slate 

 near Hudson, Troy and Albany. Anthracite, beds in New- 

 port, R. I., in Worcester, Mass., in Fort Miller, Troy and 

 Fishkill ; and in small quantities along Hudson River, for 



* I found reeds in the anthracite coal at Worcester, Mass. Ferns have been 

 found in abundance in the anthracite at Newport, R. I. 



