Geology, Sc. of the Connecticut. 51 
~ wacke* may be found ving between the greenstone and the 
sandstone, as at Gallows-Hill near Hartford, and on the 
west side of the Berlin jatiges of greenstone. Some of the 
greenstone occurring in the dykes of this rock in old red 
sandstone, has a similar aspect. At the junction of the 
coal formation and greenstone below the falls in Gill, the 
columuar tendency of the latter rock entirely disappears, 
and for several feet, the greenstone is distinctly, thoug 
somewhat irregularly, stratified; the strata being parallel 
to the sandstone. ‘This may be seen to most advantage at 
very low water; and the same may be seen, though less 
distinctly, along the whole eastern border of this range of 
greenstone ; and something of it on the east side of all the 
— ranges along the Connecticut. It ought here 
to be remarked, wpe = this rock appears quite different 
in its composition o eastern side, especially-of the 
range passing seca Deer and Greenfield. The in- 
durated clay seems in a great measure to take the place of 
the hornblende, and the basis of the rock has a wacke-like 
appearance. Much of it is amygdaloidal;. but the imbed- 
ded minerals are usually quite different. On the east side, 
the most abundant is chlorite, having a radiated aspect, and 
green earth; whereas, on the west side, this is scarcely to 
be found. The radiated zeolite on the west side is finely” 
fibrous; on the east side, the crystals are larger and trans- » 
parent, resembling the Thomsonite of Dumbarton in Scot- 
Jand. The rock on the eastern side is, also, more decom- 
po than on the o nt side. 
The eastern side of this rock is not, however, all amyg- 
daloidal: Near where Deerfield river passes through the 
range, on the north bank, this rock contains ‘distinct crys- 
tals, or rather plates of felspar; and thus becomes a porphy- 
ritic greenstone. “It even approaches to ophites,” says 
Professor Dewey. The same rock contains good prehnite, 
and in the prehnite may be found Ae bbe copper. 
I should judge that about one half of the greenstone of 
the Connecticut constitutes the base of amygdaloid, and 
very much of it appears to be genuine toadstone. The cavi- 
ties are usually spheroidal or almond shaped,. a 
reniform, and frequently cylindric. Those of the latte 
*[ have recently found wacke perfectly well eevee ied very 
abundant, at the foot of the very lofty mural precipices, two miles north 
of Monte Video, on the Talcot mountain, ten miles W. of Hartford.— Editor 
