Geology, &c. of the Connecticut. a5 
tain between Durham and Northford; and sometimes on 
distance from the bottom to the top of the ledge. This 
débris is highly inisteation to the chronologist, because it 
urnishes him with a decinige 
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 s este top finds its 
way into ig esarnae: tape yg a columns, and there 
freezes in the winter, and by its expansion removes the 
rock a little from i its ‘place. This ope is repeated, 
year after year, and thus some part of the pi 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, ee in the es above him and in 
the ruins beneath them, of recent instances of this kind. 
ing winters.* 
ow 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 ete them eecupi- 
Poo ! it was 
common musquito. 
all over with them as soon as the avalanche thundered. The Hon. Eliha 
Hoyt informs me he found a swarm of these creatures in the winter, in a 
ollow tree 
