FOLDS AND FAULTING. 409 



The Alps consist of about a dozen main folds, but 

 the total number of secondary ones cannot be estimated. 

 Nevertheless, taking the whole of the great movements 

 into consideration, the earth has been reduced by no more 

 than a hundredth of its previous circumference. Pressure 

 may have already commenced its action in Cretaceous or 

 Eocene times, the highest existing fold being in all prob- 

 ability the earliest, and at the time that the outermost post- 

 Miocene Alpine chains were being formed, the inner zones 

 were already undergoing denudation and erosion. Seeing, 

 however, that the Central Alps are higher than the outer 

 ridges, it follows that elevation must have been more rapid 

 than denudation. 



We must now call attention to a special case involving 

 the highest conception of a fold as yet submitted to the 

 notice of geologists. We refer to that of the Great Glarner 

 Doppelfalte or Doublefold. Commencing near the Central- 

 massif, west of the Reuss, it continues as far as Ragatz, 

 the northern part of the fold having a length of ninety kilo- 

 metres, and the southern, one of forty-eight. In the whole 

 of this region, on both sides of a central axis, older beds of 

 Verrucano overlie the younger Eocene, the two being 

 separated by a limestone complex, the Lochseitin Kalk, 

 in which Escher von der Linth, after much wearisome 

 research, found Jurassic Belemnites and Ammonites. The 

 theory propounded supposes that at this point intense fold- 

 ing had taken place in two opposite directions ; the arch 

 has moved forward, whilst the trough has travelled in the 

 opposite direction. The septum, or middle limb, being 

 drawn out owing to the advance of the arch, has at the 

 same time been squeezed out between the arch and trough 

 cores. In the above case, through this movement the 

 whole series from the Permian to the Upper Jurassic is 

 only represented by a highly altered limestone a few metres 

 in thickness. 



The above-named two trough limbs are connected deep 

 beneath the surface, and the Eocene core being compressed 

 between the two foldings has itself become enormously con- 

 torted and bent. The theory of plasticity already referred 



