20 
GEOLOGY OF THE THIRD DISTRICT. 
sition to assume, in parts, the porphyritic character, presenting crystalline particles, which 
are globuliform and not angular, manifesting the same law as in gypsum and other minerals, 
but upon a minute scale. 
Associated with gneiss and granite there are a few other rocks, but they are rare in the 
third district; some of them formed by one or more elements of granite or gneiss, with am- 
phibole or hornblende, forming sienite, granito-sienite and hornblende rock; likewise some 
aggregates of which granular carbonate of lime is the base, and others more rare, in which we 
find pyroxene and table or tabular spar. It is with hornblende rock, granite and gneiss, that 
magnetic iron ore, the characteristic ore of the range, is usually associated. Another and a 
common occasional aggregate is that of gneiss and granite with garnet, which was seen in 
place, in several localities, but is often met in boulders, as well as the hypersthene rock, which 
was not seen in the district in place, and probably was derived from the second district, where 
it is an abundant rock. 
The rensselaerite of Dr. Emmons occurs in the district, near to Lewisburg furnace, where 
the white variety predominates. It is also found to the east of Boonville, some distance from 
the river, from whence very beautiful specimens have been brought. This mineral, from its 
great beauty, the high polish which it admits, the facility with which it can be worked, and 
from being found in considerable quantity, will in great measure supersede many of our com¬ 
mon mantel ornaments of stone, as well as other smaller ones. 
The primary rocks cover but a very small area of the district, in'comparison with the two 
eastern ones; further details, therefore, would seem superflous, as full illustration will be 
given by the reporters of those districts, especially by Dr. Emmons, being but an appendage 
to his central mass ; also by the mineralogist of the State : the subject being again introduced 
in this report, under the heads of those counties where these rocks form a part of the surface. 
The wood cut No. 1, placed at the head of the chapter, is a good illustration of the joints 
or fractures which this rock usually presents in the district, when it shows a mural surface. 
It was taken by the side of the Utica railroad, facing the river at the east end of the gap at 
the uplift of Little-Falls. 
The localities where the primary rock appears insulated from its central mass, showing 
itself as a protruded body, are but few in number. The first along the Mohawk going east 
is at the Noses, being found on both sides of the river, at the east end of the uplift, rising on 
the south side to about one hundred feet; the greatest height being at some distance from 
the river. It shows itself in three distinct patches on that side, and but one on the other, all 
of different heights, the result of an original uneven surface ; for the whole mass there, from 
the undisturbed state of the calciferous and other rocks which rest upon it, must have been 
raised as one body. 
The next place along the Mohawk is Little-Falls. There the primary rock attains to nearly 
the same height, at the east end of the uplift; its surface dipping west, and disappearing 
under the river and its superincumbent masses. The rock exhibits a local character of some 
interest, which was noticed with detail in the report of Herkimer county. Some of the nume¬ 
rous vertical joints on the south side of the river are coated with red oxide of iron, often very 
