part 4] SCANDINAVIAN ' MOUNTAIN PKOBLEM.' 391 



majority of workers, considered not to be Pre-Cambrian, but 

 later. 



As to the igneous rocks of the metamorphic cover, their later 

 (Caledonian) age and intrusive character must now be considered 

 proved in a great many districts. The thrust igneous rocks that 

 mast still be regarded as Pre-Cambrian, like the porphyries at the 

 front of the thrust-masses in Jemtland, do not seem to be of more 

 than local importance. 



As to the metamorphosed sedimentary rocks lying above the 

 unaltered rocks, the main question has been whether these rocks are 

 to a great extent equivalents of the Sparagmite Division, or 

 whether they are younger. It was stated above that, on Torne- 

 bohm's hypothesis, the Sparagmite Formation (which by some has 

 been regarded as a parallel to the Torridonian of Scotland) is 

 referred to the Pre-Cambrian, a fact that made the existence or 

 non-existence of these rocks above the fossiliferous Cambro- Silurian 

 a question of considerable general importance. 



Among Norwegian geologists the Sparagmite Formation, or the 

 Sparagmite Division, as it may perhaps better be termed, has not 

 generally been regarded as a true Pre-Cambrian series. In 

 Kjerulf's stratigraphical system the division was classified together 

 with the fossiliferous Cambro-Silurian rocks, as a basal series 

 (stage la), and Brogger has regarded the Sparagmites as a basal 

 Cambrian division (' Focambrian '). Becently J. Kiasr has empha- 

 sized 1 that the division should naturally be placed in the true Lower 

 Cambrian. Seen in this light, the question of the occurrence of 

 the Sparagmite Division in the thrust-complex has no such primary 

 importance, as in general the true Pre-Cambrian has not 

 been thrust. We are, in any case, dealing with rocks which 

 originally belong to horizons above the Pre-Cambrian surface. 



Yet the Sparagmite Division, with its huge thickness, several 

 thousand feet, of coarse clastic rocks, is a stratigraphical element 

 of singular importance, and the question of the part which this 

 element plays in Scandinavian mountain geology is therefore 

 naturally one of very great interest. While it must now be con- 

 sidered proved that Tornebohm's Seve Group in many districts is 

 no equivalent of the Sparagmite Series, but of later Cambro- 

 Silurian age, yet it is beyond doubt, as will be stated further 

 below, that in places in Southern Norway the thrust-masses to a 

 large extent primarily belong to the Sparagmite Division, and thus 

 are older than the oldest-known fossiliferous Cambrian sediments 

 in the same districts. 



It being thus evident that in different areas different strati- 

 graphical members make up the thrust-masses, what is the reason 

 for this ? Does there seem to be any general rule as to the 

 constituents of the thrust-complex in different districts ? 



The question may be answered thus : In the thrust-masses 



1 l The Lower Cambrian Holmia Fauna at Tomten in Norway' Viclensk. 

 Skrift. Kristiania, 1916. 



2e2 



