338 THE GEOLOGY OF THE ALPS. [XIV. 



examples with that of the gneisses with chloritic and micaceous 

 schists, which in western Scotland, according to Murchison, 



tk fossiliferous Lower Silurian beds, and are by him re- 

 gaided as younger. This, upon the authority of Murchison, 

 Favre regards as a singular and anomalous fact. It should, 

 however, be said that this view of Murchison is rejected by 

 Ni. -oil, who explains the appearances as the result of disloca- 



nid oversliding of older crystalline schists upon the newer 

 fossiliferous beds, in which case the western Highlands will 

 form no exception to the general law of similar appearances in 



\ijis a in 1 Pyrenees. (Ante, page 271.) 



The fact that the Jurassic rocks in the valley of Chamonix 

 paw beneath the crystalline schists of Mont Blanc was first no- 

 ticed by De Saussure, and was afterwards observed by Bergmann 

 and by Bertrand, who argued from this that the limestones were 

 older than the gneiss. Bertrand's paper, as noticed by Favre, 

 occurs in the Journal des Mines, VII. 376 (1797-1798). 

 Later, in 1824, we find Keferstein inquiring whether these 

 overlying gneisses and protogines might not be altered flysch 

 (that is, eocene), a view which he subsequently maintained. 

 Similar views have found favor among later geologists ; we find 

 Murchison asserting the eocene age of certain Alpine gneisses, 

 mica-schists, and granites ; while Lyell has suggested that the 

 protogines, gneisses, etc., of the Alps may have resulted from 

 the alteration both of secondary and tertiary strata. (Anniver- 

 sary Address to the Geological Society, 1850.) Studer has 

 taught that the flysch of the Orisons has been changed into 

 crystalline gneiss, while Rozet and Fournet, with Lory and Sis- 

 monda, have assigned to the Jurassic period the great system of 

 giMMm, with talcose and micaceous schists, which make up 

 Monte Ccnis and Pelvoux, and much of the mountains on the 



BOOl and in the Valais. 



Ilutlon, as early as 1788, had taught that what he called the 

 primary schiste were sediments, the ruins of earlier rocks altered 

 by heat, but it does not appear that he attempted to fix the 

 relative age of any such altered rocks. In fact, the notion of 

 geological periods, based upon the study of fossils, was not as 



