86 M. Keilhau's Theory of Granite^ and other Roclcs, 



and granite formations which have their petrographical charac- 

 ters so distinctly marked, and which, therefore, are so easily 

 recognised, are not at all to be found in any place in the whole 

 country, except within the boundaries of the two transition ter- 

 ritories ; veins of greenstone only, more or less similar in com- 

 position to the greenstones of the transition series, are to be met 

 with in other localities. It is thus perfectly clear that at least 

 all the other numerous massive formations, which occur more 

 especially in the Christiania territory, are most intimately con- 

 nected with the group of transition-strata of which we are 

 speaking. In Sweden, as we shall afterwards see, massive for- 

 mations occur of the same kind as ours, and there they are as- 

 sociated with a sandstone like our own, with orthoceratite lime- 

 stone, with clay-slate, &c. The genetic connection — for less it 

 cannot be — between these two kinds of rock, the above-men- 

 tioned stratified and unstratified, is particularly apparent in 

 looking over the map of the Christiania territory ; for it is im- 

 possible to ascribe this connection to accident, and it would be 

 a poor shift for any one to say that the places where the mas- 

 sive rocks in question occur, offered less resistance to the erup- 

 tions than any others. 



Having premised these preliminary observations, we will 

 now consider the subject in a more special point of view, by 

 examining the distribution of the massive rocks within the limits 

 of our territory. First of all, I should be inclined to lay par- 

 ticular weight on the constant association of the great porphyry 

 masses, or rocks belonging to the great porphyry districts with 

 members of the sandstone-formation, viz. those slates, quartzos 

 sandstones and conglomerates, which occur in the upper porJ 

 tion of the stratified rocks of the group. It is not a mere coi 

 jecture, but a fact, that the presence of this sandstone-formj 

 tion affords the condition required for the occurrence of tl 

 great porphyry masses. However poor the Upland territoi 

 may be in unstratified rocks, yet we soon perceive that thi 

 massive formation presents itself wherever these sandstones ai 

 visible ; and, in the territory of Christiania, I know only oi 

 locality where this same porphyry is not associated with th< 

 sandstone. The stratified rocks are for the most part bound* 

 by the granite districts ; but wherever sandstones occur in th( 



