M. Keilhau's Theory of Granite, and other Rocks. 85 



ramifications of the massive rock in the bounding strata, and 

 generally the relations of the boundaries and positions of these 

 rocks — relations which have of late been much more carefully 

 examined — by assuming a simultaneous formation of these 

 rocks which often occur together in such a peculiar manner. But 

 after what has been said this mode of escape will not suffice ; 

 for should it be maintained that the granite of the transition 

 territory had intruded itself at the same time that the strati- 

 fied rocks were deposited, it might perhaps be said, with re- 

 spect to the ramifications in the primary rock, that these were 

 upfillings of the vein-fissures then open in the basis of the new 

 formation. But ramifications in the primary rock, together 

 with transitions into the same, might just as well imply a si- 

 multaneous origin with the last as with the new formation. 

 But it is not our object to combat opinions which have been 

 excluded from the science, and which can only preserve their 

 name in its history. It is, on the contrary, those views which 

 have stood their ground against all the hypotheses hitherto 

 proposed that we have now more strictly to examine. 



For this purpose it will be enough to present a group of 

 facts. Every one who has, even with the smallest degree of 

 attention, examined our territory, must have made the remark 

 that the great porphyry districts are regularly to be found 

 where sandstone occurs ; and that eurite-porphyry is associated 

 more particularly with alum- slate. Meanwhile, the supporters 

 of the eruption theory may, perhaps, lay no great weight on 

 these circumstances, which may appear to them as altogether 

 accidental, and they will not feel themselves incited to investi- 

 gate how far there exists a fixed place in certain stratified 

 rocks of a particular kind for massive formations ; for if we 

 consider the latter as having burst forth from the interior, they 

 might of course have made their appearance at any place 

 whatever, without reference to the mineralogical constitution 

 of the mountain-rock broken through by the eruption. That 

 such an assumption, at least with respect to our massive rocks, 

 is incorrect, and that it would prevent us from observing some 

 of the most beautiful and important phenomena of our terri- 

 tory, we shall now have an opportunity of shewing. 



I must first of all remark in general, that all those porphyry 



