IGNEOUS ORIGIN OF LIMESTONE. 
51 
where the limestone has the appearance of having 
been protruded between the layers of gneisS) 
which it has disturbed. The limestone is gra¬ 
nular, and what is particularly worthy of notice, 
is its mixture with serpentine ; an association so 
constant, that there .is scarcely an exception in 
the northern counties. Its presence serves to keep 
up the analogy between those beds which occur in granite ; while the presence of serpentine, 
which is an acknowledged igneous rock, goes far in itself to support the theory of the 
igneous origin of the limestone. 
In 13 the limestone not only appears to have protruded upward, and disturbed the beds of 
gneiss, but also to have produced an important change in the adjacent portion in immediate 
contact with the limestone. It appears like a band of trappean matter, of a darker color and 
more compact than the gneiss. It is possible to be deceived as to the cause of this change in 
the proximity with this mass of limestone; but that it is some way connected with the in¬ 
fluence of this rock, seems highly probable. It is to be observed, that the limestone of this 
locality is not a pure white crystalline rock : it is brown or grey, mixed in part with quartz and 
hornblende, and in incoherent masses or grains. It is obscure, and does not form a prominent 
mass in the rock, and might therefore pass unnoticed, unless the attention was directed to it. 
]4. 
a. Hornblende, b. Liinestone. c. Sienite. d. Granite. 
The next mass of limestone associated with the schistose rocks, and to which I would 
direct the attention of geologists, is at Port Henry in Essex county. It is that mass, too, 
which has already been pronounced upon as one which exhibits evidence of the metamorphic 
theory. This bed of limestone is extensive, and occurs near the. lake ; it projects out of the 
side hill in a very prominent manner, and forms a conspicuous object from several points of 
view. There are several points of interest which may be examined with profit in this vici¬ 
nity ; but I would particularly refer the geologist to this bed of limestone, as one well worthy 
his examination, occurring as it does in a situation quite accessible, and associated with horn¬ 
blende, gneiss, etc. 
