192 Reviews — Alph. Favre's Geological Researches 



such varied lithological character into anything like a regular classifi- 

 cation. 



Yet, after all, the author candidly indicates how much still 

 remains to be done before every mass of the Western Alps can 

 be assigned with precision to its normal equivalent in the undisturbed 

 regions of the world. Thus, his inferences as to the age of the supposed 

 oldest stratified rock, the Protogine of Mont Blanc, are of an enquiring 

 rather than a conclusive character. Many pages are, indeed, devoted to 

 the development of his theoretical views of granite having been formed 

 in an aqueous manner, though, in adopting this view, he admits that 

 granite was a decomposed subterranean lava ; and as sub-aerial lavas 

 also contain water, we do not appreciate the value of this subtle dis- 

 tinction. But apart from this theory, when he states his belief, that 

 granites were formed in this wise during very early or ante-palaeozoic 

 eras, his hypothesis seems untenable when we consider the conflict- 

 ing evidences with which this troubled region abounds, and wherein 

 no true sedimentary rock, as proved by infraposition and fossils, is 

 older than the Carboniferous era. It is a region, we repeat, void 

 of a recognizable base, — the Laurentian, Cambrian, Silurian, and 

 Devonian rocks, and even the Carboniferous limestone, having here 

 no representatives with fossil animal remains ; and believing that 

 the granitiform and porphyritic rocks of the Alps are, geologically 

 speaking, of no high antiquity, we demur to the assumption that 

 they can be connected with earlier geological times. 



If we follow the author along his mountain walks among the 

 highest Alps of Maurienne and the little Saint Bernard, and see 

 how he recognizes the complete overthrow of formations of great 

 dimensions, in so crystalline a state, we see that the distinction 

 between what used to be known as igneous and aqueous rocks is 

 in many places almost evanescent. For, whether we side with him 

 or not in his belief in the sedimentary origin of many of these 

 quasi- stratified granitiform masses, we have before us sufficient 

 proofs of disturbance to account for the grand fan-shaped arrange- 

 ments and convolutions involving great overthrows, which he 

 describes, to say nothing of the stupendous rents and fractures 

 which abound in this tract. 



Even when he is treating of his only really recognizable funda- 

 mental formation in these Western Alps, — the strata containing 

 old coal plants, — we see how this formation is irregularly followed 

 by distinct superincumbent secondary formations in diff'erent parts 

 of the chain. Thus, the so-called ''Trias" is nowhere characterized 

 as in the Eastern Alps, by possessing its true central Muschelkalk 

 fossils. On the contrary, it is composed of highly schistose and 

 crystalline masses with gypsum and dolomitic limestone. And, 

 as if to render the confusion greater, in a vast portion of this 

 western chain, particularly in the Maurienne and Savoy, even 

 this equivalent of the Trias is wanting ; and the Lias and Jurassic 

 rocks, with their fossils, are not only placed at once in contact with 

 the Carboniferous rocks, but the two are convoluted in so many 

 rapid plications, that eminent geologists have been unable to 



