Geology, S^c, of the Connecticut. 55 



tain between Durham and Northford ; and sometimes on 

 both sides, as Menitick mountain in Granby, Ct. Mount 

 Carmei in Hamden, and Mount Tom in East-Hampton, at 

 its southern extremity. The broken fragments of the green- 

 stone, of almost every shape, seldom of any regular figure, 

 and of various sizes, usually slope up more than half the 

 distance from the bottom to the top of the ledge. This 

 debris is highly interesting to the chronologist, because it 

 furnishes him with a decisive 



Cosmogonical Chronometer. 



Every one who lives in the vicinity of these greenstone 

 ridges knows, that every year adds to the loose masses at 

 their base, at the expense of the columns above. The wa- 

 ter infiltrated through the thin soil on their tops, finds its 

 way into the narrow seams between the columns, and there 

 freezes in the winter, and by its expansion, removes the 

 rock a little from its place. This operation is repeated, 

 year after year, and thus some part of the rock is pushed 

 so far over the precipice that its center of gravity falls 

 without the base, and it comes thundering down, usually 

 dividing into very many pieces. Sometimes, if the foot of 

 a column gives way in this manner, the whole column 

 above, perhaps twenty or thirty feet long, is precipita- 

 ted, like a glacier, on the loose rocks below. Sometimes 

 only one or two of the lower joints fall out, leaving the 

 principal part of the column suspended, the shuddering ob- 

 server can hardly tell by what. He will also see evidences 

 in very many places, both in the ledge above him and in 

 the ruins beneath them, of recent instances of this kind. 

 Indeed, in almost any place along these mural points, two 

 or three of the outer columns are easily removed by the 

 application of a lever, being loosened by the ice of preced- 

 ing winters.* 



Now every one must see that this levelling work cannot 

 have been going on forever ; and when we consider how 



*On tearing down some of these columns a few years since, during the 

 winter, in search of chabasie, &;c. I found the spaces between them occupi- 

 ed by an immense swarm of the common musquilo. Poor insects ! it was 

 all over with them as soon as the avalanche thundered. The Hon. Elihu 

 Hoyt informs me he found a swarm of these creatures in the winter, in a 

 hollow tree. 



