248 Dewey's Geological Section. 
with quartz. By the action of the weather, sec rocks are 
divided into innumerable prismatic bodies. A small stream, 
which rises in the mountains in the East part of Grafton, 
and runs westward into the Hudson, below T roy, affords 
an excellent opportunity for examining the ober of this 
rock in numerous places. Occasionally there appear in 
this rock, beds, or veins, of a reddish argillaceous slate, in 
Grafton and Brunswick. 
Near Troy, the graywacke has a much finer texture, and 
darker colour, and some of it takes a fine polish.* Where 
- e graywacke stops near Troy, there begins a bed or stra- 
of 
 erittiieots Slate.—It extends to the bank of the Hud- 
son, and has a similar inclination to the East. It hte 
doubtless be considered as the next rock in order 
forming an extensive bed in the graywacke. It is "full of 
natural seams, which divide it into small plates, and easily 
a ag A large quantity, eee into a street in 
y the action of the weather, and constant travel- 
ling hits "tk become in one year, baile e clay. Both the 
graywacke and argillite are evidently transition rocks.* The 
slate is very different from that which oceurs in Williams- 
town, and along this part of the Taconick range, and which 
ms to me clearly primitive. It will doubtless be found 
by future observation, that the roof-slate of Hoosack, N. ¥ 
which appears to be a continuation of the Taconick range, is 
separated from the argillaceous transition slate, which ex- 
tends for many miles along the Hudson, below and above 
Troy, by the same stratum of graywacke, I noticed no 
gray wacke-slate on this section, but it is found very ane 
in Chatham, a few miles southeast of Albany. Specim 
of the above rocks will soon be forwarded to the Cleotogical 
society. 
Should you think the above worthy of publication, I 
should be glad to see it because this section will be pretty 
vate nee from atone miles East of ——— river to 
e Hudson. 
* * * a * * 
* See Eaton’s Geology. 
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