74 Professor Favre on the Geoloyij of the German Tyrol. 



The two exterior chains are formed by dolomites and lime- 

 stones, presenting an ai'id aspect. These mountains are so 

 white, that their rocks are frequently confounded with the 

 snows which occupy the most elevated summits. 



The rocks whicli form these three chains are considerably 

 varied in their nature, in the modifications to which they have 

 been subjected, and in their age. 



In the extensive depressions of the ground, which separate 

 nearly all the exterior chains from the central one, we find 

 many sedimentary formations. 



Volcanic actions have here and there pierced the surface 

 of this district, which has been so subject to geological acci- 

 dents, and have brought various poi'phyritic rocks to the sur- 

 face. They have thus complicated the structure and the na- 

 ture of the ground. 



The central chain appears to reach its maximum of eleva- 

 tion at Weiss-Kogl (11 ,840 feet*), near the glaciers of CEtz 

 and Gross Glockner, which are 11,662 feet above the level of 

 the sea. This sharp peak bears a great resemblance to the 

 numerous aiguilles situate to the south of the valley of Cha- 

 mounix. The Venediger-Spitz, at the bottom of the Pinzgau 

 and the Wild Spitz, likewise among the glaciers of CEtz, 

 almost rival the preceding mountains in height. 



In the secondary chain to the north, the most elevated 

 summit appears to be the Dachstein (9234 feetf) in the Salz- 

 kammergut ; in respect to elevation, then come the Ewiger- 

 Schneeberg, the Steinernes-Meer, ko.. ; while, in the southern 

 chain, the rocks of Marmollata, attaining a height of 10,400 

 feet, appear to exceed the other parts of the chain. 



The crystalline rocks of the central chain are formed of true 

 granite, the component parts differing in size. Often, with- 

 out becoming exactly gneiss, this rock assumes an appear- 

 ance which Saussure has well named veined granite.\ The 



* These measurements, talcen from G. Mayr's map (Munich, 1846), are in 

 French feet. 



t According to M. Simony, 9493 Viennese feet (Memoires de la Societe des 

 amis des Sciences de Vienne, t. i., p. 317, 1847). 



I Voyage dans les Alps, § 163. 



