6 GEOLOGICAL MEMOIRS. 



stones frequently do not form uninterrupted beds, but on the bedding- 

 surfaces have the appearance of numerous and irregularly interrupted 

 stripes running parallel to the dip of the strata, if the latter are in- 

 clined or bent. The component parts of these stripes consist of the 

 bisected surfaces of very differently shaped calcareous nodules. There 

 are places where these nodules occur in such quantities side by side 

 and over one another, that one can almost believe he has before his 

 eyes a limestone-conglomerate of which the clay-slate forms the ma- 

 trix or cement. This, however, would be an erroneous view of the 

 case, as is evident from the perfect gradation apparent in the con- 

 dition of these rocks, passing from the thickest strata of fossiliferous 

 limestone, through the thinner but still uninterrupted calcareous beds, 

 to the interrupted layers of the same, and from these again to those 

 resembling conglomerate. 



From the consideration of the joint occurrence of the clay-slate and 

 limestone in the Christiania territory, it results, with regard to the 

 probable history of their origin, that, as chemical masses, both rocks 

 were for the most part conjointly deposited during the same geological 

 period, — that certain circumstances brought about the local predomi- 

 nance of one or other of these masses, — and that, lastly, the lime- 

 stone beds, at least the smaller layers, were exposed to the influences 

 that produced a more complete separation and segregation of the car- 

 bonate of lime, resulting in the formation of the nodular bodies. No 

 new chemical products were thus generated, if we except some iron 

 pyrites and calc-spar, the former of which is sprinkled here and there 

 and even occurs in small nodules, and the latter is sometimes met 

 with in the state of thin crusts. It is, however, quite evident that 

 nowhere along the lines of demarcation have there been formed any 

 bodies as the result of the contact of the clay-slate and limestone. 



Let us now study this geological area at its line of junction with 

 the granite. About six miles * south-Avest of Christiania, not far 

 from the palace of Gjellebak f, granite appears ; and here, at more 

 than one spot, we meet with a very favourable opportunity of becoming 

 acquainted with the behaviour of the peaceable fossiliferous Transition 

 strata towards their once so unquiet neighbour. But we must first 

 observe, that near Gjellebak the calcareous rocks play a much less 

 subordinate part than at many other places in the territory of Chris- 

 tiania. We here meet with some large calcareous beds which on the 

 Paradies-Bakken run up more or less closely to the granite ; and 

 here the latter cuts the strata nearly at right angles to their strike. 

 South-east of Gjellebak, on the contrary, from the Kjenner mines to 

 the Ulve Vand, the strike of the beds for the most part runs parallel 

 to the edge of the granite, and at the same time the limestone is here 

 far less prevalent, and indeed in some instances quite subordinate. 



The Limestone, Clay -slate, and Granite of the Paiadies-BakJren. — 

 We do not find here the thick limestone of Christiania, but a granular, 

 crystalline, white marble, the age of which is sufficiently attested by 



[* The measurements in this paper are German. — Trans.] 

 t See the Map above-mentioned. 



