SCHEERER — LIMESTONE IN CRYSTALLINE SCHISTS. , 



its rare but recognizable fossils *. When the marble and clay-slate 

 alternate with each other in beds of varying thicknesses, the latter has 

 quite an altered character. It has become harder and more compact, 

 partly allochroitic, partly passing into a nearly pure siliceo-calcareous 

 mass. The surfaces of contact between the limestone and the altered 

 clay-slate are frequently traversed with crystallized garnet. The 

 garnet is locally so prevalent that thin clay-slate beds appear quite 

 changed into masses of garnet, or are represented by accumulations 

 of garnet crystals. Moreover a mineral similar to tremolite, accom- 

 panied by interspersed zinc-blende, is found at some points near the 

 edge of the granite. The development of these minerals and meta- 

 morphosis of the strata have taken place in general without any par- 

 ticular disturbance of the stratification. This is especially observable 

 on the sides of the quarries which are worked for the marble. Beds 

 of altered clay-slate, sometimes scarcely more than a line in thickness, 

 continue parallel and rectilinear for long distances. Still there are 

 places where such beds are much cracked and fissured, and on the 

 rock-surfaces appear almost like bran in bread. It is therefore evi- 

 dent, that the limestone, before it took on its present crystalline cha- 

 racter, was in the condition of a plastic mass, in which the clay-slate 

 lay as a harder body. 



Calciferous Clay-slate and Granite between the Kjenner mines and 

 the TJlve-Vand. — On the Paradies-Bakken we were made acquainted 

 with the changes that the neighbourhood of the granite had produced 

 in an area of clay-slate very rich in limestone ; from the tract v^dthin 

 the above-mentioned points we recognized the changes arising from 

 a similar action on a clay-slate on the whole destitute of limestone, or 

 rather only impregnated with more or less carbonate of lime. These 

 conditions are shown approximately by the following diagram, in a 

 vertical section : — 



Here a is granite ; h, an allochroitic bed, with much crystallized 

 garnet, from a few feet to a much greater thickness ; c, hard (altered), 

 clay-slate, only here and there allochroitic ; b', an allochroitic bed 

 similar to b ; c', hard clay-slate, gradually (but only within extensive 

 tracts) passing into a generally soft clay-slate. It is evident that b 

 and b' have formerly been calciferous, c and c', on the contrary, non- 

 calciferous clay-slate beds, and hence the explanation of the appa- 

 rently pai'adoxical occurrence of c between b and b' . 



Both in the Gjellebak and Kjenner mines district, and at many 

 other places along the granite border, there are points where the hard 



* In particular I noticed a Catenipoya in the Geological collection of tlie Uni- 

 versity of Christiania. 



