82 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 otlier, 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 rliange to the influence of one single cause, caloric, but extend it 

 to all ihiids 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, neitlier 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. 



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 

 arc granular, white and clouded ; but the position they respectively occupy is quite diflferent. 

 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, chondrodite, 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 1)1 ue limestone of the New- York series, I maintain the doctrine that they belono- 

 to a limestone sid g««t'rw, of another age, born under totally different conditions, A vein 



