!»N ROCKS AT CAMDEN. 



An inspection of this section, which comprises an extent of about three quarters of a 

 nnli'. furnishes an epitome of the bets disclosed l>y the rocks upon this range. The first 

 mass a is the magnesian slate, much wrinkled, and containing masse* as well as scams of 

 quarts: it is the north portion of the uplift, where the descent becomes rapid towards the 



ri\er. 



/>. in the Stockbridge limestone, clouded, lumpy as ii appears upon a weathered surface, 

 intermixed with quartz, siliceous reins, talcose matter, etc. Its beds, when worked, oiler 

 veins of calc spar, and imperfect veins of magnesian matter, which appears to result from 

 the decomposition of felspar. The soft matter contains dodecaliedral crystals of carbonate 



of lime, Willi 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 

 Wilhamstown, Massachusetts. I have called it magnesian, though probably it is merely 

 a porcelanous day. 



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 oi macles of brown 

 staurotide appear. Some of the laces may be made out; thej possess onlj the general 



form of a crystal, hut are disclosed by weathering. Nothing at all determinate appears 

 by fracture. 



/(. At tins point in the section, a mass ,,f quartz conies in, of a bluish color; grain and 

 li rture 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 home 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. 



A. Fine brown granular quartz, portions of which are conglomerated : it. is the principal 

 mass ,,f (piart/., possessing all the characters of the same kind of rock in Massachusetts, 

 Vermont and New-York. It is mterlaminated with a dark fine siliceous slate, occurring 

 in mass, though much contorted. Portions resemble tin 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 /'. alter 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 o\er which it las. 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 



