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OBSERVATIONS ON METAMORFHISM. 
The question of metamorphism has nothing to do with the question of identity with other 
and distant masses. It may be, and doubtless is true in some sense or other, that heat is 
not necessarily the agent in metamorphism. But that molecular attraction, exerted under 
a variety of circumstances and conditions, may and does modify and change the particles 
from an earthy to a crystalline condition, I believe is the true foundation of the doctrine. 
I would not restrict this change to the influence of one single cause, caloric, but extend it 
to all fluids in their several modifications, as water, steam and gas, as well as to the dry 
heat of contact with an incandescent mass; and still more emphatically to the agency of 
the molecular forces, by which regular forms are produced, and a constant tendency to 
arrange symmetrically all the constituent particles of which a mass is composed. With these 
views, we shall find all rocks metamorphic in a small degree. All the forces of nature 
have operated upon them as masses, as well as upon every constituent part; and they are 
not now what they were once, neither will they continue to be what they are now. Those 
incessant powers of motion which pervade the universe, never cease to act upon solid rocks 
and thus cause their elements to move: even the light of heaven, penetrating the super¬ 
incumbent crust, awakens to energetic action those subtle agents. 
v • ' ... 
In closing my remarks upon the Stockbridge limestone, I wish to state that this is by no 
means the rock which I described in my report as a primary limestone. It is true that both 
are granular, white and clouded; but the position they respectively occupy is quite different. 
Thus the primary limestone is always an unstratified, rock, and is analogous to granite ; 
but when it occurs among stratified schists, as gneiss and mica slate, etc., it puts on some 
of the characters of a parallel bed, a contemporaneous rock, and so does granite. That it 
is not one of the blue, or any of the older sedimentary limestones metamorphosed by heat, 
is fully shown by the inspection of those masses which rise out of the hypersthene rock of 
Essex, and the granite and gneiss rocks of St. Lawrence counties. In the latter county, 
the very beds of Primary limestone are exposed by the destruction of the once superincum¬ 
bent Potsdam sandstone. So far, then, from being one of the sedimentary limestones, 
its position shows without a question that it can not but have been anterior in age to any 
of the lower limestones of the New-York system. 
These peculiar primary limestones occur in all the northern counties and in the county 
of Orange in New-York, and in Sussex county in New-Jersey; and they abound in fine 
minerals, as spinelle, sapphire, idocrase, cliondrodite, graphite, hornblende, pyroxene, 
mica, etc. As to the presence of these bodies, I believe them to have been developed by 
the same forces as in granite ; or, in other words, that they were not, in the great range 
of limestone in the counties designated, produced by an action upon the rock subsequent 
to consolidation, that is to say, they are not metamorphic minerals. In this expression of 
opinion, I do not deny the possibility of their production by the metamorphic process ; but 
having seen the same minerals so frequently in a mass which, under no rational hypothesis 
could be a blue limestone of the New-York series, I maintain the doctrine that they belong 
to a limestone sui generis , of another age, born under totally different conditions. A vein 
