194 Reviews — Alph. Favre's Geological Researches 



study of this work of M. Favre, and its numerous illustrative 

 diagrams. For he shows clearly, that the gi*eat valleys and lake 

 basins are greatly due to original geological impress. Adopting this 

 view, he has ably refuted the theory, that the depression of the Lake 

 of Geneva could have been duo to erosion by ice, that cavity having 

 been a necessary and confluent depression accompanying the great 

 contiguous upheaval of the central mountains, as indicated by de 

 Saussure.^ 



Nothing indeed can more strongly support the original ^^ew of that 

 great man, as worked out by Favre, that the main outlines of the 

 Alps are due to subterranean influence, than the following aphorism 

 or law of Studer, derived from a life-long study of his native country, 

 Switzerland, and which M. Favre puts in these words : — 



"Toutes les fois que les couches en forme de C ont le dos toume 

 aux Alpes, les couches anciennes sont a I'exterieur et les couches 

 modernes a I'interieur, et reciproquement, toutes les fois que les 

 couches en forme de C ont le dos toume en dehors des Alpes, les 

 couches anciennes sont a I'interieur et les couches modernes a I'ex- 

 terieur." (Vol. ii.) 



The question of the greater or less permanency of the older ex- 

 ternal features of the earth, as due to subterranean geological action, 

 has indeed been recently brought into discussion among British 

 geologists by an appeal to the stratified crystalline rocks of the 

 Central and Western Highlands of Scotland by the Duke of Argyll. 

 On this point, however, it may at once be observed, that no two 

 regions of the earth present greater differences in lithological and 

 geological structure than the Highlands of Scotland and the Alps. 

 In the former, the great and central mass consists of Lower Silurian 

 rocks, for the most part crystallized, and occupying highly inclined 

 and convoluted positions, they rest quite unconformably on the older 

 Cambrian and Laurentian rocks of the west coast, the latter having, 

 indeed, an entirely divergent direction to the others.^ Now all the 

 old crystalline rocks of the great central region are uncovered by any 

 Secondary or Tertiary rocks, or indeed by any trace of their former 

 existence ; such deposits being only known to have occurred on the 

 centre and western flanks of this primeval chain. In the Western 

 Alps, on the contrary, as has been shown, no recognizable Palaeozoic 

 rocks exist below the Carboniferous, and these are surmounted by a 

 variety of Secondary and Tertiary deposits, some of which reach to 

 the highest summits, and are often in a metamorphosed and crystal- 

 line state. Now, whilst the geologist has to ferret out amidst such 

 varied rocks, the movements from beneath, which have given to the 

 Alps their main configuration, it is the rocky simplicity of the 

 Central Highlands, and the character and appearance of the ancient 

 rocks there rising everywhere to the surface, which have led the 

 able author of the " Reign of Law" to express his opinion, that when 

 those metamorphosed and crystalline Lower Silurian rocks assumed 

 their main outlines, they were in a folded, broken, hardened, and 



1 See M. Favre's letter thereon to Sir R. Murcliison, Phil. Mag., March, 1865. 



2 See Siluria, 4th Edit. Frontispiece, Map, and pp. 24, 163. 



