240 Dr. Cooper on Volcanoes 
extends southward from Massachusetts near.Vermont,: to 
that part of Connecticut. East and west rocks at New Ha-. 
ven, consist of columnar greenstone. 
Proceeding southward, the trap or greenstone rocks in 
New Jersey that form the margin of the Hudson river, de- 
scribed by Dr. Samuel Ackerley, in his geology of the Hud- 
son river, p.32, and that cover the old red sandstone, are 
indubitably volcanic; figurate columnar quadrangular, pent-' 
angular, hexangular, basalt, with greenstone and amygda- 
loid. 
From thence to the falls of the Passaic, I have had no 
opportunity of examining personally. 
At the falls of Passaic I spent some time in akamituiog 
the rocks: I have no seruple in pronouncing them basalt of 
all textures, appearances and composition—compact—po- 
rous with prehnite, and carbonat of lime and zeolyte —figu- 
rate in trihedral, tetrahedral, but chiefly in pentagonal 
prisms—some dull when struck, some ringing. This mass 
of fleetz trap, is poured over the old red sandstone. In very 
many places, this undermost rock is porous and manifestly 
burnt at the place of contact and for some inches downward. 
Of this appearance, among others, | have specimens too de- 
cided to leave any doubt of their igneous. origin to those 
who will make an honest use of their eyes. 
This trap formation, as it is called, extends about 40 
miles from the Hudson toward the Delaware ; L entered it 
at three several and distant places ; I collected every where 
porous basalt with carbonat of lime, prehnite, and occasion- 
ally zeolyte ; as well ascommon basalt, greenstone and figu- 
rate basalt, all graduating into. and connected with each 
other. I examined this chain, in three places at about ten 
miles distance from each other, and I am satisfied of the 
nature of the rock. Whether it crosses the Delaware I do 
not know, but I think not. 
On the road side from Princeton. to Brunswick in New- 
Jersey, is a manifest Basalt formation, consisting chiefly 
of figurate clinkstone... I have not traced it. , 
About eleven and a half miles from Philadelphia, de- 
scending a hill, on the Ridge turnpike road, there is a for- 
mation of about one hundred yards broad, that I have trac- 
ed from thence across the Scuylkill, for a considerable dis- 
tance beyond the Gulph mills in Montgomery County. It 
