MEDLICOTT — ALPS AND HIMALAYAS. 43 



gives an ample refutation of the notion, nnivcrsally adopted by con- 

 tinental geologists, of the iissiiring- by elevation as an origin for 

 valleys, transverse or longitudinal ; his argument applies by impli- 

 cation against accepting contortion as evidence of elevation. The 

 contortion of the Miocene strata is, however, accepted as proof that, 

 after the Miocene epoch, the rocks of the Alps were much disturbed, 

 suiRcientlj so to alter the drainage-system in all its details. In the 

 Molasse itself the inversion of the rocks of the lligi is quoted as a 

 measure of the action. 



Sir Charles Lyell, in his ' Antiquity of Man ' (p. 309), adopts 

 generally the views which connect the disturbances of the Molasse 

 with, and as proof of, the last series of movements to which the Alps 

 owe their present form and internal structure, dissenting from those 

 views so far as they include the production of the lake-basins. 

 He combats, I think effectually, Professor Hamsay's theory of the 

 formation of the great Alpine lakes by glacier erosion ; while at the 

 same time (in assigning unequal subsidence of large areas as the 

 main cause of these lakes) he introduces glaciers as an almost 

 essential adjunct, to prevent silting up pari passu with the subsi- 

 dence. The absence of lakes in non-glacial mountain-regions is 

 accounted for in that way. In appealing to the undisturbed, yet 

 2)r[Bglacial, lacustrine deposits on the lake of Zurich against the 

 theory of Prof. Hamsay, Sir Charles Lyell seems to overlook that 

 this evidence tells with as great force against the use he himself 

 makes of glaciers in the production of those lakes ; for the lake of 

 Zurich must by his process of formation have attained its maximum 

 extension and depth when the deposits of Utznach and Diirnten 

 were formed, i. e. before the glacier-period. 



The Molasse does not come within the range of Professor 

 Theobald's recent work on the Grisons * ; but the author would 

 seem to allude to the contortions of those rocks when he says (p. 7) 

 that only on the north did the upheaval of the Alps find an obstacle, 

 in the earlier formed crystalline mass of the German Mittelgebirge. 

 In M. Heer's valuable work on the geology of Switzerland f, there 

 is scarcely any tangible allusion to physical geology. The author 

 seems to adopt the current opinions upon the last great upheaval of 

 the Alps, subsequent to the Molasse period. 



' Der Gebirgsbau der Alpen ' ought to be an exact complement 

 and suitable companion to ' Die Urwelt der Schweiz.' M. Desor's 

 work J:, however, in no real sense fulfils this expectation ; there is 

 not a single section in it, nor anything like a critical matter-of-fact 

 discussion of Alpine rock-structure. The history of the Alps is 

 divided into two great periods, before and after the last mountain- 

 upheaval. From the early Praslias land the centre had progres- 

 sively risen, but unequally and with oscillations. On the south the 

 Pliocene deposits suifered the same disturbances as the Miocene; so the 



* Geol. Besclireibung der N. O. Grebirge von Graubunden. Bonn, 1864. 



t Die Urwelt der Schweiz. Ziirich, 1865. 



\ Der Gebirgsbau der Alpen. Wiesbaden, 1865. 



