242 Dr. Cooper on Volcanoes 
The flcetz trap formation of our north eastern states, ex- 
tends higher than Deerfield, Massachusetts ; and perhaps 
to the New-Hampshire line ;* see Mr. Hitchcock’saccount 
of that region in Prof. Silliman’s Amer. Journ. of Science. 
These rocks contain agates, prehnites, carbonat of Lime, &c. 
I have specimens. Part of Mr. H’s account will be found to 
afford strong confirmation of much of Dr. Cooper’s opinion. 
T know nothing of the brown Augit mentioned by Mr. 
Eaton at Pine rock. The only augit I have seen, as an 
American specimen, was in the possession of Dr, Bigsby. 
of the British staff from the neighbourhood of Montreal. 1 
think New-Haven is the most southerly point of this forma- 
tion in Connecticut. East and West rocks in New-Haven, 
which are said to be miniatures of Salisbury Craig, are com- 
posed of Trap rocks based on what is esteemed the old red 
sandstone. ‘They are columnar, with considerable regu- 
larity, containing prehnite in seams and nodules, with Zeo- 
lites; and in one case I met with some quartz crystals. 
The appearance of these two mounts seems like that of the 
Palisadoes on the Hudson, which however I have seen 
only at a distance. The forms of the rock are. various ; 
more commonly trapezoidal: they are used with their natu- 
ral surfaces exposed externally in buildig the walls of a 
church in New-Haven. ‘They are often found in thin La- 
mina, which in place have their edges vertical, and are ex- 
cellent clinkstones ; they are frequently irregular. 
About two or three miles east in East-Haven, there are 
numerous parallel ridges of similar rock, but for the most 
part, without any regular jointed structure abonnding in 
different places with agates, chalcedony, and amethystine 
quartz geodes,} carbonat of lime, analcime, Prehnite and 
ereen earth. In some spots this basalt, if basalt it be, is 
found in spherical balls. In one or two instances it alter- 
nates with the. sandstone which has been mentioned ; and 
where the two come in contact, the sandstone is somewhat 
altered: whether by heat or not Ido not pretend to say. 
ig DPa 
Look at Hitchcock’s map of the Connecticut river in 
1 Sillim. Journ. 105, for the Greenstone breaking through 
* It extends a few miles into Vermont not New-Hampshire.—Ep. 
+ Are not the Geodes of Oberstein, Lava? T.C. 
