Geology of a part of Massachusetts, §c. 241 
occurrence of these rocks nine times* in. the distance of 
three miles, making four alternations of the two, and 
leaving the mica-slate on the west of the limestone. 
The county of Dutchess lies directly south of Columbia 
county, and extends to the state of Connecticut. The 
small county of Putnam, which contains the principal part 
of the highlands east of the Hudson, is on the south of 
Dutchess county.. . 
The mica-slate of the Taconick mountain is continued 
southwards along the western part of Salisbury and Sha- 
ron, Con., and inclines rather more to the west, passing 
towards the highlands and a little east of them, and leav- 
ing some portion of the counties of Dutchess and Putnam 
on the east of it. I crossed it in two places, and found 
the mica-slate associated with primitive argillaceous slate 
upon both sides of it, as described in the above geology, 
Vol. VIII. p. 19, of this Journal. The granular limestone 
is continued parallel with the range of mica-slate along 
the east side of Dutchess county, and, according to infor- 
mation, of Putnam county also. It is associated, as in 
Berkshire county, with great quantities of dolomite, so 
friable as to be continually falling into sand, and of com- | 
mon magnesian limestone. There can be no doubt of the 
continuation of the range or beds of primitive limestone in 
this direction from Berkshire county towards Long Island 
Sound. 
The rocks between this range of mica-slate and the 
highlands I was not able to examinc. Although it is very 
desirable to have the result of an examination of this sec. 
tion; the continuity of this range of mica-slate cannot be 
affected by it. For, if this range of mica-slate should be 
distinctly connected with the gneiss of the highlands, it 
would only show the repetition of some of the older 
rocks on the west of the mica-slate, and nearer to the 
transition rocks. If transition rocks are interposed be- 
tween the two, the highlands would only be more dis- 
tinctly separated from the primitive rocks of New-Eng- 
land. 
* With respect to Salisbury this fact is mentioned, p. 211, Vol. Il. of this 
Journal, dn the authority of the Editor. 
Vor. VIII. No. 2 31 
