i aaa 
Geology of Deerfield, &c. 109: 
its summit. This ridge does not rise so high as the pudding- 
stone on the west of it, as may be seen in the view of strata 
with the map. It commences on the west bank of Connecticut 
river, about a mile north of the hill C, and increases in eleva- 
tion nearly to the spot where it disappears at the fall of the 
river in Gill. This rock does not appear to rest on sandstone, 
but to descend through it, where there is an opportunity for 
observation. Deerfield river has worn a passage through the 
sandstone and greenstone 150 feet deep, and the greenstone 
passes under its bed, and the sandstone, at a few rods distant 
lies on each side of the greenstone. A similar fact has been 
noticed at the fall in Connecticut river, in Gill. Yet I have 
coloured this greenstone secondary on the map; for it is cer- 
tain that Mount Tom rests on sandstone, and it is stated by 
Professor Silliman, that the same rock does in Connecticut. 
Could we penetrate deeper below the surface, it is probable 
the same would be found to be the case with this greenstone. 
As stated above, this rock disappears near the cataract in 
Gill, and it is succeeded by puddingstone. But four miles 
farther north, it again emerges in Bernardstone, though it 
rises but little above the surface. Here its character is 
changed. The hornblende is more crystalline, and the rock 
becomes decidedly primitive, as you approach a mountain of 
argillite and mica slate, into which it passes, and no greenstone 
as been observed north of this. It terminates not far from 
the line of Vermont. The red sandstone and conglomerate 
also terminate on the opposite side of the river in Northfield. 
T € greenstone, in the above described range, is of a finer 
texture than the same rock in Connecticut; and the feldspar, 
ii some Specimens, is scarcely discernible with a microscope. 
Indeed, in many instances, the eye would decide the rock to 
be basalt. Much of it is fissile, the lamine varying from half 
’n inch to a foot in thickness. ‘This is most perceptible among 
the loose Masses ; but it exists also in that place. Whether 
this circumstance be accidental, I will not attempt to decide. 
arge proportion of the greenstone of our vicinity consti- 
tutes the base of amygdaloid. ‘The imbedded substances are 
calcareous Spar, quartz, chalcedony, analcime, prehnite, &c. 
