72 Geology, fyc. 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 

 intermediate rock. But as coal has been found there, (Am, 

 Journal of Science, vol. 3, p. 248,) a strip has been colored 

 brown, rather to mark out the locality than the extent, of 

 the coal formation. It is not improbable that some more 

 experienced geologist than myself, may hereafter include 

 the rock I have marked old red sandstone on the east side 

 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. All 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 (he slates. 



To avoid mistake: I 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- 



