Geology, ^,c. of the Connecticut. Q5 



substance of the rock, which I have sometimes suspected 

 might he petrifactions ; and perhaps they are so. Vv hen 

 this rock is disintegrated it forms an admirable material for 

 the construction of roads; a good example of which may be 

 seen In the road between Hartford and Weathersfield. 



Where the profile crosses this rock, it has a dip of 45° ; 

 and as already observed under the article greenstoue, it 

 here mounts upon the back of the greenstone forty or fifty 

 feet. If we follow the junction of these rocks southerly, on 

 the west bank of the Connecticut, we shall find the slate con- 

 forming to the irregularities of the greenstone, thus forming 

 saddle shaped strata. In some instances we notice a sudden 

 curve from this cause, of 90°. At the first copper mine we find 

 on passing down the river, a narrowspur of the greenstone ex- 

 tends a short distance into the slate, and the vein of ore here 

 passes from the greenstone into slate. Haifa mile south of 

 this point we find the slate crossed obliqueiy to the direction 

 of the strata by parallel seams dividing it into strips from one 

 to six inches wide and often five feet long. Sometimes we find 

 in these divisions six sided prisms of quartz, lying partially 

 imbedded and exhibiting both terminations in great perfec- 

 tion. I have seen seams very narrow containing green car- 

 bonate of copper, the sides of the vein being beautifully gla^* 

 zed, having a highly specular aspect, and forming the saal- 

 bande of the Germans. The width of the rock on the sec- 

 tion is about fifteen rods, extending across the mouth of Fall 

 river. 



No. 10. Greenstone — (No. 1.) This has been already 

 described when treating of that rock. Thickness of the for- 

 mation, 20 rods. 



No. 11. Same as No. 9. (No. 3.) Thickness of the stra- 

 tum, 6 rods, dip 45°. 



No. 12. Red Slate — resembles the last, but is more mi- 

 caceous, is divisible into thinner laminae, the surface of which 

 is even, and the color is less red. A beautiful rock Thick- 

 ness 6 feet, dip 45°. 



No. 13. Redd, ,h micaceous sandstoneSomewhai con^ om.- 

 erated, the imbedded pebbles of quartz and flesh colored fel- 

 spar, smail and rounded, less fissile than the last, layers 

 thicker. Thickness twelve feet, dip 40°. 



No. 14. Same as No. 12. Thickness 15 feet, dip 40°. 



No. 15. Same as No. 9. Thickness 15 rods, dip 40°. 



Yol. VI....N0. I. 9 



