98 
ROCKS AT CAMDEN. 
An inspection of this section, which comprises an extent of about three quarters of a 
mile, furnishes an epitome of the facts disclosed by the rocks upon this range. The first 
mass a is the magnesian slate, much wrinkled, and containing masses as well as seams of 
quartz : it is the north portion of the uplift, where the descent becomes rapid towards the 
river. 
b , is the Stockbridge limestone, clouded, lumpy as it appears upon a weathered surface, 
intermixed with quartz, siliceous veins, talcose matter, etc. Its beds, when worked, offer 
veins of calc spar, and imperfect veins of magnesian matter, which appears to result from 
the decomposition of felspar. The soft matter contains dodecahedral crystals of carbonate 
of lime, with rough surfaces, which appear to have been formed in the soft matter after its 
decomposition. The same material is found in numerous places in the limestone at 
Williamstown, Massachusetts. I have called it magnesian, though probably it is merely 
a porcelanous clay. 
A trap dyke traverses the hard slate, succeeded very soon by a granitic vein, f and g 
are portions of fine and coarse slate; in the latter, imperfect crystals or macles of brown 
staurotide appear. Some of the faces may be made out; they possess only the general 
form of a crystal, but are disclosed by weathering. Nothing at all determinate appears 
by fracture. 
li. At this point in-tlie section, a mass of quartz comes in, of a bluish color; grain and 
texture that of the common granular quartz. It is sixty or seventy feet thick ; and from 
its presence and relations, I have been led to entertain the opinion that two distinct masses 
of quartz belong to the system. This fact is borne out by the rocks of Berkshire, Massa¬ 
chusetts. Two masses, for instance, appear which are not in the same range, though it 
is not clear that one is superimposed upon the other as at Goose river, Maine. 
m. Magnesian slate. 
K. Fine brown granular quartz, portions of which are conglomerated : it is the principal 
mass of quartz, possessing all the characters of the same kind of rock in Massachusetts, 
Vermont and New-York. It is interlaminated with a dark fine siliceous slate, occurring 
in mass, though much contorted. Portions resemble the talcose slates, in which, as in 
Rhode-Island, a greenish granular mineral appears, more like-epidote than any thing else. 
Bands of yellow slate also appear, resembling those of Massachusetts which furnish the 
ochry iron. 
At f, after rising up from the gorge of the river, and passing over the succeeding ridge 
some forty or fifty rods, a fracture appears, which brings the magnesian slate nearly in 
contact with the quartz over which it lies. It contains at this point also imperfect macles. 
That the quartz is beneath this mass of slate, is proved by another fracture nearly at right 
angles to this one, and but a short distance to the westward, where both masses are brought 
up, the quartz being beneath, and bearing the slate with its peculiar imperfect minerals. 
The dip and trend in this case is changed to the west and north. 
The thickness of the limestone at this exposure is about two hundred and fifty feet. 
The portions of the beds adjacent to the others are more or less slaty and impure. The 
