VJ OBSERVATIONS ON METAMORPHISM. 



The question of metamoiphism baa nothing to do with the question of identity withothei 



and distant masses. It may be, and doubtless is true ill some sense m other, that heat is 



not neressaidv tlie agent 111 metamoi phism. But that molecular attraction, exerted under 

 a variety of circumstanoes 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 tins change to the mlluence of one single cause, caloric, hut extend it 

 to all fluids in their several modifications, as water, Bteam 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 SJ mmctrically 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 he what they are now. Those 

 incessant powers of motion which pervade the universe, never cease to act upon solid rocks 

 and tints 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 Stockhridge limestone, I wish to state that this is hy 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 unstratificd rock, and is analogous to granite ; 

 hui 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 "I" 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 blue limestone of the New-York series, I maintain the doctrine that they belong 

 to a limestone ru* generis, of anothei age, born under totally different conditions. A vein 



