THE GREAT SCANDINAVIAN OVERTHRUST 401 



arrangement, in the case of the Scottish Highlands, to selective 

 metamorphism having converted the upper beds into schists, 

 while leaving the lower beds unaltered. This view was also 

 adopted in Scandinavia. It assumed, in accordance with the law 

 of superposition, that the overlying beds must be the younger, 

 and the chemical difficulties of selective metamorphism were 

 left for subsequent explanation. That these difficulties were 

 great was evident in Scandinavia from the observations made 

 by Gumaelius in Offerdal during 1869. He then showed, in a 

 section reproduced as fig. 2, the existence of a block of mica 

 schist overlying phyllites or clay slates, with relations which 

 selective metamorphism could hardly explain.^ 



Murchison's theory was overthrown in Scotland by the 

 discovery that the crystalline schists had been thrust into 

 positions where they appear to rest conformably on younger 



W. 



il. """"""^ 



Q = Quartzite. si = slate. M.S. = Mica Schist. 



Fig. 2. — Section in Offerdal by Gumaelius. 



beds. And the same explanation has been demonstrated in 

 Scandinavia, although there it appeared at first almost incredible 

 owing to the vast scale of the phenomena. 



The literature of the Scandinavian overthrust is somewhat 

 scattered, and it is mostly WTitten in Swedish or Norwegian. 

 Hence a brief statement of some conclusions and reference to 

 the original authorities may be of value to British geologists. 

 It has recently been my privilege to examine one of the typical 

 overthrust sections on the shores of Lake Tornetrask in Swedish 

 Lapland. For directions and kind help in this visit, and for 

 showing me the material bearing on this question in the 

 museums at Stockholm and Upsala, I owe my warmest thanks 

 to Prof. Hogbom of Upsala, Dr. Gunnar Anderson, Director of 

 the Geological Survey of Sweden, and Dr. Holmquist, of the 

 Technical High School of Stockholm. Nor must I omit mention 



^ This section was referred to byTomebohm in 1873,6'z'^r. Geol. Unders.Ajhandl. 

 No. 9, p. 42 ; but it apparently remained in manuscript until it was published by 

 Hogbom in 1894. 



