26 GEOLOGICAL MEMOIRS. 



of Frencli mining operations : the Western Alps : the Swiss Alps ; 

 and, lastly, the Eastern Alps. 



After this introduction follows the first division of the work, which 

 is devoted to the central zone of the Alps. 



Alpine granite, gneiss, and crystalline schists. — The determina- 

 tion of the age of the granite of the iVlps, which Jurine thought to 

 establish by the introduction of the name Protogine, is the boundary- 

 line between old and modern geology. The production of these 

 crystalline schists by the metamorphosis of sedimentary matter, and 

 the explanation of these processes agreeably to the laws of chemistry 

 and of physics, together with the old question whether these rocks 

 have their origin in water, or in heat, or in both conjointly, are looked 

 upon by the author as problems standing out foremost in the field of 

 geologic inquiry for solution, now as much as fifty years ago, and 

 which his own experience leads him to believe will not speedily be 

 solved. 



To this subdivision belong the ''central masses" of the Aiguilles 

 Rouges, of Mont Blanc, of the Finsteraarhorn, of St. Gothard, and 

 the Alps of the Valais, respectively : afterwards, those of the Tessine 

 Alps, the Adula, Sureta, and Maritime chains, of the Bernina and of 

 the Selvretta, and lastly that of the Oetzthal Ferner are considered. 



The Alpine granite, or protogine, of the central mass of the 

 Aiguilles rouges frequently puts on a gneissose structure. At the 

 end of the last century considerable mines of argentiferous galena 

 and of copper were opened near Servoz. In the workings near 

 Promenaz lead and copper mixed with baryta occur. Granite in the 

 form of veins has penetrated not only the crystalline schists but also 

 the limestone formations. The southern flank of the Dent de Morcles 

 gives indications, which deserve to be followed up. 



In theorizing on the elevation of the Alps, the similarity of the 

 central granite nuclei to trachyte domes is always striking, however 

 anomalous the conditions are proved to be on closer examination. 

 These granite masses appear to have been raised up over long fissures, 

 as a trachyte cone over a central cavity ; the whole mass, in a solid 

 or soft state, having been actually forced upwards ; or, early sedi- 

 mentary deposits, penetrated by fluids or gases, have been thereby 

 modified in condition and increased in volume so as to swell up to the 

 mountain-heights here spoken of. 



In the nucleus of Mont Blanc as in that of the Aiguilles Rouges 

 protogine prevails, especially on the eastern side, and from thence 

 towards the centre. No geologist who examines the rents in these 

 rocks, their slender pinnacles, and the abrupt precipices which 

 surround the Mer de Glace at the Montanvert and the glaciers lying 

 behind it, can believe that the present form of Mont Blanc is that 

 which it originally bore. One might almost believe that the mountain 

 after its first formation had been elevated to its highest point in the 

 district of the upper Tacul glacier, and that by a subsequent sinking 

 of the mass the deep glacier-valley extending from the Mer de Glace 

 to the summit of Mont Blanc had been occasioned. Mont Chetif 

 and Mont de la Saxe rise like two vast pillars on the sides of the 



