Geology, ^c. of the Connecticut. 19 



nishes an admirable stone for such purposes ; and many 

 quarries are opened in it. Immense tatles of it may be 

 procured, and should the mania for constructing pyramids 

 ever seize the inhabitants of New-England, this gneiss might 

 produce masses of stone rivaling in magnitude the im- 

 mense limestone blocks of the pyramids of Egypt. 



The gneiss of the Connecticut, often alternates whh mica 

 slate, and passes into it. In Granville, may be seen gneiss, 

 hornblende slate and mica slate, in various stages of ap- 

 proach to each other, and making various alternations. 



This mixture of gneiss with other rocks, and the consequent 

 indistinctness of character, render it, in some instances, not 

 very easy to give its limits. I have felt this difficulty espe- 

 cially in regard to the northern part of that gneiss range 

 which occupies the eastern part of Litchfield County and 

 appears so decided in its characters in Bristol, Plymouth, 

 and Canton. In the west part of Granville, I feel confident 

 gneiss is the prevailing rock — although mica slate alternates 

 with it. Yet between Chester and Westfield there is nothing 

 but mica slate, as the prevailing rock, which extends twelve 

 or fourteen miles west of Chester, before we come to gneiss. 

 And north of this we find very little gneiss within the limits 

 of the map except a narrow stratum as we ascend the hill 

 from Cummington to Goshen. I do not, therefore, feel ex- 

 actly satisfied with the northern termination of the Litch- 

 field gneiss as given on the map : but at present it is not in 

 ray power to re-examine it. 



1 would here, however, suggest that I have been rather 

 inclined to believe that some of the stratified rocks along 

 the Connecticut pass gradually into other rocks laterally, 

 that is, in the direction of the strata: — mica slate, for in- 

 stance, into gneiss, or hornblende slate; and argillite into mi- 

 ca slate. To establish this fact, however, requires a long 

 series of very close and accurate observation. I merely 

 suggest it, therefore, and do not assert it. 



In some instances, the ingredients of our gneiss are pret- 

 ty equally mixed: in others they are arranged in somewhat 

 distinct layers, which are generally straight. It is not a 

 rock that is rich in minerals with us. Veins of granite tra- 

 versing it, however, sometimes contain interesting specimens. 

 Witness the Haddam minerals. 



