and Writings of Baron Leopold von Buck. 219 



actions of the Academy for the year 1818-19.* The conchi- 

 sion was very near, that in the interior of the earth there re- 

 main volcanic masses which may have caused the elevation of 

 the whole chain of the Alps, and that these very naturally ap- 

 pear at the surface, where they succeeded in tearing asunder 

 the principal mass of the mountains, and where no resistance 

 opposed further obstacles to their breaking forth. 



This remarkable fact, which is immediately connected with 

 what Saussure believed himself obliged to conclude upon 

 grounds of an entirely different description, respecting tlie 

 opposite termination of the Alps, viz. the chain of Mont 

 Blanc, was soon after confirmed by an important series of ob- 

 servations by Buch, which exercised the greatest influence 

 on the development of our views as to the origin of mountain- 

 chains generally. The scene of these observations was the 

 Southern Tyrol on both sides of the Etsch-Thal, and some 

 neighbouring mountainous districts, more especially towards 

 the east. 



Views regarding Porphyries and Dolomite, — For a long period 

 previously, the attention of naturalists had been attracted by the 

 occurrence of a mass of porphyry (a rock which does not occur 

 elsewhere in the Alps), in Southern Tyrol, and more espe- 

 cially along the road leading by Brixen and Botzen, from the 

 Brenner to Italy. In that neighbourhood, on the left bank of 

 the Etsch, in the valley of Fassa and its lateral valleys, the 

 mountain- chains are particularly distinguished by their re- 

 markably broken outline, and by the abrupt and bold relief of 

 their isolated projecting summits. These features attracted 

 Buch for several years in succession to this part of the Alps, 

 and he here detected the key to the explanation of important 

 geological relations. 



He ascertained by minute examination, that the mass of 

 porphyry mentioned above consists of two entirely distinct 

 formations. The one is characterized by its prevailing red 

 colour, and by the invariable occurrence in it of entirely sepa- 

 rated grains of quartz ; its predominating ingredient is felspar. 

 The other porphyries, on the other hand, resemble basalt in 



* LeonluwVs T(u^cJienbuch, 1821, p. 467. 



