f 
i 
i 
b 
J 
= §c. of the Connecticut. 17 
ture. 
This porphyritic granite is carefully to be distinguished 
from glandulous gneiss, which also-occurs abundanily along 
the Connecticut. Let any one pass from Hinsdale, New- 
Hampshire to Winchester and he willsee numerous bowlders, 
often ten feet diameter, of a rock having the granite constit- 
uents and exhibiting no appearance of a schistose structure. 
In one place at least he will cross the rock in place ; and he 
will have no doubt that it is the most decided granite. And 
yet it is Fs porphyritic. This rock cccurs also in 
Chester where Dr. Emmons has traced a range of it five or 
six se _Nennieu bowlders of this rock are scattered 
over the town of Woodbridge near New-Haven: but T do 
not know from whence they originated. 
Pseudomorphous Granite. 
I put this adjective to a variety of granite that occurs along 
the Connecticut, not to show my dexterity at coining new 
terms, put to make myself understood. I am inclined, how- 
ever, to think that the rock to which I refer is not exactly de- 
scribed in the geological books which I have seen, unless 
ithe by Cleaveland, when he says, “some varieties (of gran- 
ite) are divisible into imperfectly columnar or tabular con- 
eretions.” (Mineralogy, vol. 2, p. 732.) It is a coarse 
grained granite with light coloured quartz and feldspar, ar- 
ranged i in the usual manner. The peculiarity lies in the mi- 
ca. This is usually dark coloured, and arranged in plates 
from one to three inches across. The manner in which 
these are disposed, may be thus explained. Su 
quartz and felspar to have been cemented together so as 
to form a perfect graphic granite. Next suppose the mass 
to be cut in various directions by a fine saw; and in the 
spaces thus made, imagine thin plates of mica, not more 
than * of an inch tick, to be — It is obvious that the 
Vor. VI.—No. 
