in the Counties of New-Haven and Litchfield. 208 
dation at no great depth is rock, and the junction of primi- 
tive and secondary country evidently takes place in this val- 
ley. It has been supposed to contain cecal, and I know of 
no geological fact which contradicts this opinion, and there 
are some in favor of it. 
Primitive Slate Rocks. 
The hills which bound this valley on the left, are 
composed of magnificent ranges of slaty rock, which run 
parallel to the greenstone range. They rise in pretty 
abrupt hills of which the steepest sides are towards the 
greenstone : the road for some miles, runs in the valley, but 
eventually begins to rise sloping up the hills, and inclining a 
little West. Primitive -argillite, or slate, highly glistening, 
often tortuous, abounding with veins and distinct tuberculous 
masses of quartz occasionally of enormous size, is the pre- 
vailing rock on the left of the valley.* It sometimes becomes 
almost miga-slate, occasionally alternates with that rock, and 
at a junction which is distinctly visible about six miles from 
New-Haven, the two rocks are so much blended, that it is 
impossible, for some feet, to distinguish them apart, although 
at a small distance either way they are very distinct. Good 
slate for building is found in these hills and carried to New- 
Haven.} About eight miles from that town the road sudden- 
ly turns at right angles, to the left, and we now travel, not as 
before, in the direction of the strata, but acrossthem. Ar- 
gillite prevails about two miles, but manifests more and 
more a tendency to become mica-slate—it eventually under- 
goes this change very distinctly, and for six or seven miles, 
we cross immense strata of mica-slate, having the same direc- 
tion with the other slate; the strata of both are vertical or very 
highly inclined, and the mica-slate is frequently porphyritic, 
presenting distinct crystals of feldspar as large as a thumb. 
* Upon these hills there are numerous masses of white quartz, of the ap- 
pearance of rock salt, sometimes several yards in diameter, and quite un- 
connected with any rock. After seeing the slate of these hillsno one can 
doubt that the quartz has arisen from the decomposition of the shistose 
strata. 
+ Some researches for coal have been made in these slate rocks, but, it is 
extremely evident that coal cannot be found in hills that are decidely prim- 
itive ; all such expectations concerning this region are baseless. 
