SCHEERER LIMESTONE IN CRYSTALLINE SCHISTS. 9 



SO frequently in Rhombododecahedrons), occurring partly in the 

 altered Transition beds, partly in the mineral veins. In an area of 

 scarcely a square mile there are more than thirty old mines, and in other 

 parts of the district many more mines and diggings have been worked. 



The siliceo-calcareous streaks (thin clay-slate bands) occurring in 

 the marble are nowhere in this district parallel, nor in the broken 

 condition above described, but form, like the felspar in the hard 

 slates, a kind of irregular network, which, from weathering and the 

 action of water, sometimes projects ^ an inch beyond the surface of 

 the marble. 



Examples of the metamorphosis of the fossiliferous limestone and 

 clay-slate may be taken from many other parts of the Transition di- 

 strict of Christiania ; but the above are the chief phenomena of im- 

 portance. The occurrence of the following minerals, however, de- 

 serves mention. In the district of Vestfossen (between Drammen and 

 Kongsberg), in the Kirchspiel Eger, a finely crystallized Vesuvian is 

 found, under similar conditions as the garnet at the before-mentioned 

 localities. At the Ilortekolle, a mou.ntain 1^ mile to the north of 

 Gjellebiik, Ilelvine occurs with garnet ; this is rare. In AUochroitic 

 strata of the Brevig district I saw limestone-nodules (quite similar to 

 those occurring near Christiania) which were streaked with a great 

 number of small crystals of Scapolite. 



It is worthy of remark that no trace of mica appears in the dis- 

 tricts we have so rapidly traversed, either in the clay-slate or in the 

 marble. If we are to look for this as a product of the contact of 

 rocks, we should not look for it in that portion of the metamorphosed 

 clay-slate district, the calcareous components of which have favoured 

 the formation of garnet. Garnet and mica appear to hate each other. 

 Let us make, therefore, a digression to the Alun-Vand, 1 mile north 

 of Christiania. Here occurs some clay-slate apparently destitute of 

 limestone, lying in patches of limited extent (the largest not a quarter 

 of a mile long and of still less breadth) in the midst of the granite 

 and very much penetrated by granitic veins and masses. Resulting 

 from these conditions, a fine-scaled, dark tobacco-brown mica has been 

 developed in the clay-slate near its junction with the granite. The 

 clay-slate possesses throughout a gneissoid aspect, without however 

 being liable to be mistaken for the normal gneiss of Norway, and we 

 recognize a perfect similarity to the famous locality at the Solvsbjerg 

 in Hadeland, 7 miles N.N.E, of Christiania. 



Crystalline Limestone near Christiansand. — We must now set out 

 on a longer journey, to become acquainted with the iiiteresting phe- 

 nomena of the crystalline limestone of the district of Christiansand, 

 35 miles direct S.E. of Christiania. Gneiss prevails here far and 

 wide, with a strike approaching the direction of the meridian, and in 

 general with its usual steep or vertical dip. In this gneiss we meet 

 with no crystalline limestone. Where such does occur, it is in either 

 horizontal or apparently very indistinctly bedded gneiss, the relation 

 of which to the vertically bedded gneiss is not understood. The 

 stratification of the gneiss containing limestone is chiefly indicated 



