^68 M. Keilhau's Theory of' Granite and other Rocks. 



into masses that have become crystalline and heterogeneous, 

 perhaps involve the same principles. Whether the masses were 

 compact, or pasty, or quite liquid, it is probably not too daring 

 to hazard the conjecture, that the essential distinction in the 

 processes will be found to consist entirely in the time required 

 for the development of crystalline individuals. But respecting 

 all this it is necessary to wait for the further progress of inves- 

 tigation. At present my object is to protest against the de- 

 mand that our theory shall explain every thing, and against 

 the notion that, if it should not account for the phenomena of 

 greenstone veins, therefore it should be rejected in reference to 

 all the other massive rocks. 



It is, besides, by no means my opinion, that the veins which 

 I have termed independent, those namely consisting of aphanite 

 and greenstone, cannot really be regarded as metamorphic rocks 

 in the same manner as granite, the great porphyry formation, 

 and the eurite porphyry occurring in the form of beds. If it 

 is true that the veins branching out from the great masses, owe 

 their origin to the same changes which produced these masses 

 themselves, then the independent veins may have been formed 

 in the same manner ; besides, the rocks belonging to the latter 

 have perfect analogues in other masses occurring more or less in 

 the form of beds. But direct proofs are not wanting of the 

 formation of these veins by metamorphosis ; at least I do not 

 see how we are otherwise to explain a whole multitude of facts, 

 which I have described in the work already mentioned, and 

 that is about to be published ;* but, for the present, I must 

 content myself with thus referring to these facts, as the descrip- 

 tions connected with them would lead to the consideration of 

 phenomena which are partly of an extremely complicated na- 

 ture. In the mean time, I must confess that, as the study of 

 every thing relating to this subject is but newly commenced, 

 we are not yet in possession of results with which we are to be 

 satisfied. I do not, therefore, wish to attack any one'*s opinion 

 regarding these veins ; but I would remark that we ought to 



* The author here alludes to his " Gaea Norwegica," which lias been 

 jiublished since the appearance of the present memoir, and of which a short 

 account will be found in our last Number, p. 215. — Edit. 



