part 1] THE SCANDINAVIAN 'MOUNTAIN PROBLEM.' 387 



10. The Scandinavian ' Mountain Problem. 1 By Prof. Olaf 

 Holteda-HL, Ph.D. (Communicated by Sir Archibald 

 Geikie, O.M., K.C.B., F.B.S., For.Sec.G.S. Bead June 23rd, 

 1920.) 



A general feature in the geological structure of the eastern zone 

 of the Caledonian mountain-range of the Scandinavian Peninsula 

 is the existence of highly metamorphic, often gneissose, unfossili- 

 ferous rocks above slightly-altered fossiliferous Cambro-Silurian 

 sediments. This feature is met with from the Stavanger district 

 in the south to Finmarken in the north. 



It is now more than thirty years since the Swedish geologist 

 A. E. Tornebohm 1 suggested that this remarkable feature, this 

 ' mountain problem ' of Scandinavia, might be explained by 

 employing the overthrust theory : by assuming, as had proved to be 

 the fact in Scotland, that the overlying metamorphic rocks origin- 

 ally belonged to the pre-Cambrian System, and hj means of an 

 enormous thrust had been brought into their present position above 

 what was left of the Cambro-Silurian sedimentary series. 



After further investigations, inter alia in the Norwegian moun- 

 tain-district of Jotunheimen (see map, tig. 1, p. 388), Tornebohm 

 became increasingly convinced of the correctness of this view, 

 of the ancient date of, for instance, those metamorphic stratified 

 rocks of Central and South- Western Southern Norway for which 

 the Norwegian investigator Th. Kjerulf had established the term 

 ' hoif jeldskvarts ' : that is, 'Highland Quartz 1 (or Highland 

 Quartzite). In 1896 appeared Tornebohm's famous paper- on the 

 geological structure of Central Scandinavia, in which, among others, 

 the well-known sections from the Trondhjem district of Norway 

 in the west, into Jemtland in Sweden in the east, showing an 

 immense overthrust from west to east, were published. 



During subsequent years Tornebohm 1 s views were taken up by 

 several other Swedish investigators : thus by A. G. Hogbom for 

 the Jemtland district, A. Hamberg for the Sarek district of 

 Northern Sweden, and P. J. Holmquist for the Tornetrask district 

 still farther north. Yet Holmquist did not believe in the very 

 extensive overthrust, but explained the facts by assuming that 

 the roots of the thrust-masses were not very far distant. 



When the geologists of various nations met at Stockholm at the 

 International Congress in 1910, the overthrust theory was by far 

 the dominating one in Sweden. It was believed that the meta- 

 morphosed rocks of chiefly sedimentary origin — the ' Seve Group' 

 of Tornebohm — lying above the unaltered sedimentary rocks along 



1 Geol. Fr.ren. Stockholm Forhandl. vol. x (18S8) p. 3.34. 

 " ' Grunddragen af det Centrala Skandinaviens Bergbyggnad ' Kgl. Svenska 

 Vetensk.-Akad. Hand!, vol. xxviii, No. 5. 



