Dewey’s Geological Section. DAF 
ed by a stream which runs northward, into Hoosack River. 
In this valley is found abundantly the same mixture of chlo- 
rite and quartz, which is so common in Williamstown, 
though the two vallies are separated by the Taconick range, 
having an elevation from 1000 to 1400 feet. As this range 
‘is broken through by the Hoosack, a few miles North, and 
as the same mixture may be traced, and often found abun- 
dantly along the Hoosack, to the stream which runs through 
Petersburgh, the chlorite and quartz, undoubtedly follow up 
this stream, through the valley. On the West side of this 
valley, and about seventeen miles East of Troy, lies 
Chlorite Slate, very distinctly characterized. Itis some- 
times narrow, and sometimes two or three miles in width, 
often rising into hills 200 or 300 feet high. As this rock is 
found on the Taconick range, and forms a part of it, espe- 
cially a few miles North of this place, it ought perhaps te 
be considered as-belonging to the range, and as the rock in- 
to which the talcose slate actually passes. Its strata extend 
into the next rock, or 
Graywacke. This rock begins to appear about sixteen 
miles East of Troy, covering the surface in rounded mass- 
es, of very various size, and forming also vast strata, rising 
into hills in Petersburgh, constituting the mountains of 
Grafton, and extending as the general rock through Bruns- 
wick, to Troy. ‘The mountains of it in Grafton are, as 
i judge, from 800 to 1200 feet in height. It is, like 
all the other strata from Hoosack mountain to the Hud- 
son, inclined to the Kast, at various angles, from 10° to 40°. 
Its general inclination may be 20° a 25°. It consists of 
quartz, cemented by a greenish argillaceous substance, which 
generally forms the principal part of the rock, and is evi- 
dently a mechanical deposit. The quartz is sometimes 
very fine, but generally is readily seen by the eye, and is 
occasionally so large and abundant, that it resembles breccia. 
The fracture often shews the quartz to have been rounded 
masses, and in these cases the stone does not appear por- 
phyritic. In other cases the stone is so very compact and 
close-grained, containing also feldspar, that it might have pas- 
sed for porphyry, had it not been connected with speci- 
mens which could not be mistaken. This rock, though 
quite tough in the cross fracture, readily breaks into pris- 
matic fragments, along its veins, which are usually filled 
