( S63 ) 



Theory of' Granite, and the other massive Rocks, together with 

 that of Crystalline Slate ; proposed in Lectures on Geology, 

 in the University of Chr'istiania in Norway, in the year 

 1836. By B. M. Keilhau, Professor of Mineralogy. Con- 

 cluded from page 101. 



At the commencement of the transition period, the primary 

 series of rocks, with their highly inclined strata, had already a 

 surface exactly like that portion of it which is at the present day 

 exposed to our view. On this surface were deposited, under 

 the covering of the ocean, the materials for clay-slate, limestone, 

 and sandstone ; and over a great extent, certainly a somewhat 

 greater extent than the now existing transition districts, the 

 primary rocks were in this manner concealed by newer strati- 

 fied masses. These afterwards underwent disturbances, we 

 know not in what manner, which produced the high inclination 

 that prevails with remarkable regularity throughout the greater 

 part of our transition districts. Then, large portions of these 

 newer stratified tracts began by tranquil processes to become 

 converted into massive mountain-rocks ; portions, in which we 

 should otherwise now have seen clay-slate as the prevailing rock, 

 converted into granite and syenite, and sandstone portions into 

 porphyry. Nothing is more apparent to the eye than the first- 

 mentioned kind of metamorphosis, in which a gradually dimi- 

 nishing granitification can be traced into the fossiliferous strata ; 

 and where, on the other hand, sharp boundaries and felspar 

 ramifications in the slate, operate, with those individuals who do 

 not remember that analogous phenomena occur in the case of 

 dolomite, against the conviction obtained at the localities men- 

 tioned above, yet still that conviction is again strengthened by 

 the consideration of the large and small masses of slate which 

 are left in an undisturbed position in the crystalline mountain- 

 rock. A phenomenon which we did not touch on in our pre- 

 viously given volcanic representation, viz. that small, altogether 

 isolated, granite developments* occur at the sides of large 

 masses, confirms likewise the same view. 



* During my stay in Saxony in the year 1825, 1 observed analogous but 

 much less perfect developments in the limestone which protrudes from be- 



