246 Notice of a singular Conglomerate, &c. 
probably between 10° and 15°—I say probably ; for I bad 
no clinometer with me. The tuff, near the junction, has 
a partial and imperfect stratification ; but farther frem this 
line, the marks of stratification entirely disappear. In gen- 
eral, the rock is composed of rounded masses of greenstone 
(basalt ?) and sandstone, united by decomposed and com- 
minuted greenstone and wacke. Near its junction with 
the sandstone, I found a few pebbles of quartz and feldspar: 
but these are rare. The imbedded masses vary from the 
size of a pea, to one and even two feet in diameter. Most 
of these masses are compact, some are vesicular, and a 
few, perhaps, are amygdaloidal. The base too is sometimes 
vesicular, like the slag of a furnace. Near the line of 
junction, I observed in some instances, what Dr. MacCul- 
loch calls ‘‘ a troubled mixture’’ of the two rocks, and nu- 
merous alternations a few inches in thickness. The bed 
appears to be very irregular in its width—or perhaps in 
some cases the tuff alternates with the greenstone. In 
some places I noticed the width of the tuff to be between 
a quarter and an half ofa mile ; and on the side next the 
sreenstone, the imbedded nodules appeared to be less 
numerous. I! did not however find the actual junction of 
the tuff and the greenstone :—but perhaps some future ob- 
server may be more fortunate. 
The sandstone imbedded in the tuffis the same as that 
which lies above it. This fact, unconnected with others, 
would be inexplicable. But fortunately J found out a clew 
toit. Itso happens that the stage road from Northampton 
to Hartford passes over the greenstone, the tuff, and the 
sandstone, in such points as to exhibit their most interes- 
ting connexions. Jn going towards Hartford, as you rise 
easterly out of Northampton meadows, you first meet the 
old red sandstone, lying beneath the immense greenstone 
pile that constitutes mount Tom. After passing the north 
end of this mountain, a few rods beyond Lyman’s tavern, 
you cross a small stream, where, in its channel, you see the 
red slate cropping out, at a moderate dip, beneath a pile of 
greenstone. Tassing over this greenstone a few rods, you 
come to the trap tuff, and going a little farther, you meet 
the same red slate, lying above the tuff. Thus it appears 
that the greenstone contains at least one bed of the red 
slate ;—and probably more. From these, as they are below 
