72 Geology, &c. of the Connecticut. 
There are many instances, also, in which the rocks of the 
coal formation pass into the old red sandstone. Let a per- 
son go to the mouth of Fall river in Gill, where, as already 
described, he will find the red argillaceous sandstone slate 
of the coal formation cropping out below the greenstone. 
Let him ascend Fall river, and he will find this slate be- 
coming coarser, the layers thicker and the aspect changing, 
until, within a mile and a half, it becomes decided old red 
sandstone or conglomerate; the dip, also, diminishing. Or 
let him follow the road that leads from the mouth of the 
river to Greenfield, and as he ascends the hill, he will ob- 
serve a gradation from the slate above named into decided 
fine grained red sandstone. Much of the rock occurring 
along the east side of Connecticut river in Somers, Elling- 
ton, Chatham, in Middletown and Durham, appears to be 
intermediate between old red sandstone and this slate of the 
coal formation. Even in Somers and Ellington, where a 
strip is marked as coal formation, I found little else but this 
of Connecticut river as one of the members of the coal for- 
mation—but I could not do it without doing violence to my 
own convictions. 
It may be of importance in a geological view to mention 
the veins of copper ore so frequently found along the Con- 
necticut greenstone ranges. these veins which I have 
seen, or of which an account has been published, are found 
on the margin of the greenstone and coal formation; and 
the veins always pass, either laterally or perpendicularly, 
from one rock into the other. They are quite numerous, 
and we have already remarked that copper ore and iron 
pyrites are not unfrequently disseminated in the slates. 
To avoid mistake: [ will just mention different spots on 
the map that are colored as the coal formation. 1. A large 
extent in Gill, Montague and Sunderland; 2. In Granby, 
Mass. and Ludlow; 3. A small patch in Somers and El- 
lington; 4. An extensive range extending from West- 
Springfield to Berlin; 5. In Hartford, Westhersfield, Mid- 
