part 4] THE SCAN DIN ATI AN ' MOUNTAIN PROBLEM.' 389 



the eastern part of the Scandinavian mountain-belt, were an 

 equivalent of the 'Sparagmite Formation,' a thick series of 

 felspar-bearing sandstones, which in parts of Central Southern 

 Norway lie directly below the Olenellus (Holmia) Beds, and were 

 regarded as late Pre-Cambrian (Algonkian). It was further held 

 that the igneous masses of the same metamorphic cover (as, for 

 example, the amphibolites, syenites, etc. of northernmost Sweden) 

 were of Archaean age. 1 There was at that time one Swedish 

 geologist only who was in sharp opposition to the theory of the 

 thrust Pre-Cambrian masses, namely, F. Svenonius, who had for a 

 long period made investigations in the mountain-regions, especially 

 of Northern Sweden. 



In Norway matters developed otherwise. There the view that 

 the ' Highland Quartz ' of Kjerulf , the Norwegian parallel to the- 

 Seve Group, was, despite its highly metamorphosed character, geo- 

 logically younger than the phyllites and shales below, gradually 

 became the predominant hypothesis. 



In 1893 W. C. Brogger gave a detailed description of the 

 geology of the district of Hardangervidda 2 (H in the map, fig. 1), 

 where above the Archaean occur phyllites, including alum-shales 

 with Dictyocjraptus flabelliformis at the base. These phyllites 

 pass upwards into highly-metamorphosed stratified rocks (mica- 

 schists, hornblende-schists), sometimes of a typical gneissose 

 character. Brogger came to the conclusion that the latter lay 

 normally on the phyllites, that they consequently represented 

 sediments of later and probably Silurian age. The crystalline 

 character was explained as due to a combined regional and 

 contact-metamorphism which was developed during the 

 time of general deformation under the influence of huge 

 intrusions of igneous masses which had once covered the whole 

 district, and are still preserved in the central zone of deformation,, 

 in the coastal districts west and north-west of Hardangervidda. 



After 1900 Kaldhol and Rekstad published important papers on 

 the geology of these districts, where they found conditions (intru- 

 sive contacts, etc.) that could only be explained by assuming the 

 aforesaid igneous rocks to be younger than the phyllite, intruded 

 into the phyllites during the Caledonian deformation. 



This later age of the igneous masses of the South Norwegian 

 mountain-districts was further strongly emphasized by K. 0. 

 Bjortykke in 1905, in an extensive memoir 3 on the geology of 

 Central Southern Norway. Bjorlykke had first, after a visit to the 

 North- West Highlands of Scotland, endeavoured, like Tornebohm, 

 to develop the theory of overthrust Archaean masses, but further in- 

 vestigations convinced him that the actual conditions could not be 

 explained in this way. Of great importance for the explanation of 



1 See Tornebohm's article & map in Guide-book No. 1 of the International 

 Geological Congress, Xlth Session, Stockholm 1910. 



2 Norges Geologiske Undersokelse, No. 11. 



3 ' Det Centrale Norges Fjeldbygning ' Norges Geol. Undersok. No. 39. 



Q. J. G. S. No. 304. 2 e 



