410 SCIENCE PROGRESS. 



to excludes any supposition of overthrust faulting, and in 

 consequence we are forced to the conclusion that these 

 are really enormous overlying folds travelling in opposite 

 directions. We would lay special stress on the theory 

 here enunciated (see fig. i), because presently we shall 

 see that exception has been taken to the views here set 

 forth. 



The publication of Heim's valuable work, marked alike 

 by beauty of illustration and breadth of theory, undoubtedly 

 gave a great impetus to the study of these tectonic ques- 

 tions, but in justice it should not be forgotten that part of 

 any credit due to a juster appreciation of mountain foldings 

 must be given to Professor Baltzer, who, by his work on 

 the Glarnisch, and subsequently for the Swiss geological 



i -j 



Fig. i. — Illustrating Heim's theory of the Doppelfalte. 



A. Arch Limb (Mesozoic rocks mainly), now denuded away. 



B. Arch Core (Verrucano), still capping the higher summits. The dark line 

 represents the (middle limb) (squeezed out) between the arch and trough cores, all the 

 rocks from Permian to Jurassic being reduced to the Lochseitin Kalk. 



C. Trough Core (highly contorted Eocene shales). 



D and E. Trough Limb (Mesozoic rocks and Verrucano). 

 The same conditions are repeated for the Southern Fold. 



map, has done much in support of the position taken up by 

 Heim. 



In two countries especially the influence of the new 

 views early made itself felt : in Scotland, by throwing fresh 

 light on the complicated questions which had arisen, and in 

 Belgium, enabling Kohler to attack the difficult problems 

 connected with the Westphalian Coalfields (8), wherein he 

 explains these overthrusts as being due to the overturn of 

 folds, on the same theoretical basis as that adopted by Heim 

 for the Doppelfalte. The Scottish discussion, after its long 

 period of stagnation, was now re-opened, first by Drs. 



