56 Geology, dc. of the Connecticut. 
very considerable is the quantity of rock yearly detached, 
nd compare this with the whole amount of the débris, the 
conclusion forces itself upon us that the period willed this 
process began could not have been vastly remote ; in oth- 
er words, that the earth has not existed in its present form 
from eternity. Its precise age cannot, indeed, be deter- 
mined by this chronometer ; but | have often thought that, 
judging from this alone, we should be led to conclude that 
Moses placed the date of the creation too far back, rather 
than not far enough. . 
Greenstone Dykes in Old Red Sandstone. 
Professor Silliman see aap me bes an interesting locali- 
ty of these in East-Haven. They occur on the main roa 
from New-Haven to Bast: Have, ie than half a mile from 
Tomlinson’s bridge. We measured their width, and that 
of the intervening sandstone, as ott § appear on the north- 
easterly side of the road. road here passes over a 
small eminence, and the bank, on the north side, in its high- 
est part, is almost fifteen or twenty feet above the road. 
The dykes, occurring at this place, are exhibited on the pro- 
file accompan he map; and are laid down from a scale 
of fifty feet to an inch, with the intervening sandstone. In 
describing them I shall begin at the north western extremity, 
that is, at the point nearest t New-Haven: but a person wish- 
ing to find them, will do best to go first to the other end of 
the ate - because the dikes are there more distinct. 
. (See Profile.) Old red sandstone, coarse and con- 
taining pubis so as to form a conglomerate. -The dip of 
the strata is from 6° to 10° below the eastern horizon. The 
sandstone is very similar throughout. 
No. 2. Greenstone dike, 4 feet thick. * 
No. 3. Sandstone, 114 feet. This distance was measur- 
ed “4 pacing ; the other distance Me a rule. 
reenstone, one foot thic 
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feet. 
. Greenstone, 10 feet. The soil has so covered this 
and we having nothing with which to penetrate it, we 
did not actually see the dike. But the walls are distinct, 
