in Norway and in Canada, 169 



sandstones, into the fossiliferous Silurian strata of the district north 

 of Mjosen Lake. It seems therefore that the succession of these 

 groups, in the order of their antiquity, is as follows : — 



1. Primitive Gneiss formation^ 



2. Quartzose ffroup. ") ^ . . . 



^ Z' ( Primitive Slate 



5. Micaceous group. > 



4. Argillaceous and chloritic group. ) 



5. Greywacke slates, sandstones, and limestones. 



6. Fossiliferous Silurian strata. 



It is to be remarked, that besides these stratified groups, various 

 ■eruptive formations occur, whose age or place in the above list it 

 is difficult to determine. Among these, the gneiss-granite of Vest- 

 flord, and the granite and gneiss-granite in the southern parts of 

 Bratsbergs Amt are the most important. The relations of the 

 latter to the Tellemarken quartzose group, have been minutely 

 investigated by Dahll, and described in his paper " Om Tellemark- 

 ens Geologie." He there unequivocally establishes the following 

 succession, commencing with the more modern formations. 



1. Syenite with associated granite, rhomboidal porphyry and 

 augite porphyry. 



2. The Devonian formation. 



3. The Silurian formation. 



4. Gneiss-granite and granite. 



6. The slate formations of Tellemarken. 



The relations of the latter formation to the primitive gneiss are 

 not touched upon in Dahll's paper ; but in another ^' Om Kongs- 

 bergs Erts District," by Kjerulf and Dahll, it is asserted that the 

 gneiss and mica schist of Kongsberg, or as they are called, the 

 Kongsberg slates, " are exactly the same as those which in a more 

 unchanged condition, are spread over large areas in Tellemarken," 

 but separated from these by a band of eruptive gneiss-granite. 

 The primitive gneiss formation is declared to have no existence, 

 but to be resolvable into gneiss-granite, which is eruptive, and into 

 slates, whose two principal types are quartz slate and hornblende 

 slate. It is even said that gneiss " as a petrographical term, in 

 its older and more extended meaning, is no longer advantageous 

 to science, but the opposite." The order of succession in these 

 older group?, according to Kjerulf and Dahll, is as follows, com- 

 mencing wilh the oldest: 



1. Tellemarken slates. 



2. Granite and gneiss-granite. (Eruptive.) 



