XIV.] THE GEOLOGY OF THE ALPS. 331 



staurolite, and cyanite, are also met with among the crystalline 

 rocks of the Alps. A great belt of serpentine and chloritic 

 schists, traced for a long distance, may be seen at the base 

 of the Montanvert overlaid by the euritic porphyries, into 

 which they appear to graduate; the whole series, here sup- 

 posed to be inverted, dipping at about 60 from the valley of 

 Chamonix toward Mont Blanc, and overlaid by the more 

 massive gneiss or protogine. The chloritic and talcose schists 

 of the Alps have close resemblances with those of the Urals, 

 and, as Damour has shown, contain a great many mineral spe- 

 cies in common with them. Favre has, moreover, remarked 

 the strong likeness between the chloritic and talcose schists 

 and the mica-schists with staurolite of the western Alps and 

 those found in Great Britain. 



Granite, though not abundant in the vicinity of Mont Blanc, 

 occurs in several localities, the best known of which is Valor- 

 sine, where a porphyroid granite with black mica forms con- 

 siderable masses, and sends large veins into the adjacent gneiss. 

 These, with others found at the Col de Balme and in the 

 Aiguilles Rouges, appear to be true eruptive granites. Numer- 

 ous small veins met with among the crystalline schists in the 

 gorge of Trient appear, however, to belong to what I have 

 described as endogenous granites. (Ante, page 193.) Favre 

 has himself maintained that they are the results of aqueous 

 infiltration, and has noticed the fact of a joint running longi- 

 tudinally through the middle of many of them as an evidence 

 of this mode of formation. 



The uncrystalline strata in the region around Mont Blanc 

 include representatives of the carboniferous, triassic, Jurassic, 

 neocomian, cretaceous, and tertiary. The existence of an ap- 

 parently carboniferous flora, and its intimate association with a 

 liassic fauna, has long been a well-known fact in Alpine geology. 

 In 1859, Favre pointed out the existence of a zone of triassic 

 rocks in this region represented by red and green shales, with 

 sandstones, gypsum, and a cavernous magnesian limestone 

 (cargneule). These rocks had long before been referred to this 

 period by Buckland and Bakewell, but their horizon was estab- 



