GEOLOGY OF THE WESTERN ALPS. 157 



by M. Bertrand, which at once arrest attention by their 

 reactionary conclusions (6). They deal with a region of 

 the Alps not much visited by tourists at the present day, 

 though it was once familiar, as it was traversed by the old 

 coach road across the Pass of Mount Cenis. It may there- 

 fore be as well to point out that the area described is 

 situated on the frontier between France and Italy, and 

 extends from the southern end of the Mont Blanc massif 

 on the north to the famous Pass of Mount Genevre a little 

 to the south of the Mount Cenis tunnel. It therefore 

 includes the northern part of the Cottian Alps, the western 

 part of the Graians, and the eastern section of the Alps of 

 South Savoy. Diagrammatically the area may be de- 

 scribed as consisting of three zones concentric to one 

 another from a point somewhere near Turin. The outer or 

 western zone is part of the zone of Mont Blanc ; the inner 

 or eastern zone belongs to that of Monte Rosa ; while the 

 middle one is the typical area of the zone of the Brian- 

 connais. The last is composed of fossiliferous sedimentary 

 rocks of Carboniferous, Triassic, Jurassic and probably also 

 of Cretaceous age. The two outer zones are composed of 

 unfossiliferous rocks, either igneous masses or altered 

 schists. In the western zone there are the three gneiss- 

 ose massifs of the Pelvoux, the Grandes Rousses, and the 

 Belledonne with their associated schists. The eastern zone 

 consists in the main of a vast expanse of schists with 

 several gneiss massifs, such as that of Monte Paradiso and 

 those recently named the Waldensian gneisses. 



When this area was first systematically described by 

 Fournet in his elaborate " Memoire sur la Geologie 

 de la parte des Alpes entre le Valais et 1' Oisans," 1 

 issued between 1841 and 1849, the schists of the 

 eastern area were claimed to be representatives of the 

 Jurassic rocks of the central zone, altered by some 

 metamorphic agency. The age was thrown back to 

 the Trias by Professor Lory, whose monograph, the 



1 Ann. Soc. Roy. Agric. Lyon, ser. 1, vol. iv., pp. 105-183, 1841 ; vol. 

 ix., pp. 1-112, 1846; and ser. 2, vol. i., pp. 185-269, 1849. 



