MEMOIR OF LEOPOLD VOX BUCH. i^bd 



The igneous origin of basalts, the action of fire, then, Avas established, but 

 where did this formidable agent reside ? It was another French geologist who 

 ventured for the first time to answer, at great depths beneath the solid crust of 

 the globe ;* a revelation which we owe to the genius of Dolomieu, so severely 

 tried with misfortune, but endowed sometimes with an utterance which might 

 seem little less than inspired. 



These extinct craters and molted basalts, these fires at profound depths, 

 strangely interfered with the system of the excellent AVcrner, who would 

 admit of nothing beneath the granite, and could see nothing above it bi;t deposits 

 of aqueous formation.f It was a step, therefore, towards independence when 

 Leopold von 13uch ventured, first among the German Neptuuians, into the very 

 focus of vulcanism, to assure himself whether Auvergne, as it was described, 

 really pertained to the existing world. The surprise he had felt at Penagino 

 was here, of course, redoubled. Here, not nature alone offered him her guid- 

 ance, but the men of genius also who had preceded him. AVhat might not this 

 young and vigorous intelligence hope, if successful in recovering the clue of 

 those grand ideas with Avhich these localities and phenomena had inspired his 

 predecessors ! 



His exploration of Auvergne was persistent and profound. He applied to 

 it all the resources of his mind, and may be said, by this i\)rcing process, to 

 have here conceived the germs of all the lofty views to the development of 

 which his after life was consecrated. The account of this visit is filled with 

 the traces of hesitation and of eflbrt. At the sight of the basalts, he exclaims, 

 "How is it possible to believe in their igneous origin when we recall the rocks 

 which accompany them in Germany ; and yet here how is it possible to doubt 

 of it 1 " In view of the subverted and displaced strata, he says : " I see the 

 whole edifice fall to pieces which, by a sweeping arrangement of the series of 

 rocks, gave us the structure of the world at the same time with its history." 

 Contemplating that long chain of hights (Pu]js)\ which stretch in succession 

 from the Mont Dore, he is struck with a preconception of the pos^sibility of 

 the upheaval of the entire mass of these volcanoes : " What, indeed, prevents 

 lis," he asks, " from conceiving the whole mass of the Mont Dore to have been 

 thus lifted upl" 



Voltaire tells us that a Frenchman who, in his time, had passed from Paris 

 to London, would find things not a little changed. He had left the universe 

 a flenum ; he would find it a vacuum. He had left behind a philosophy which 

 explained everything by impulsion ; he would find one which explained every- 

 thing by attraction. When our young savant passed from Germany into 

 France, something of the same sort had occurred to him. 



* " The first conclusions to be drawn are, that Uert the volcanic products pertain to a mass 

 of materials which differ from granites, and are situated beneath them; that the volcanic 

 agents resided under the granite and wrought at depths very far below it." — (Dolomieu: 

 lie-port made to the National Institute on his travels in the years i798-'99.) " To be as exact 

 as possible," adds Dolomieu (as if alarmed at the temerity with which he had overstepped 

 received ideas,) "I have taken care always to use the adverb tiere, in order to restrict to the 

 precise localities which furnished my observations the conclusions I draw from them. But 

 tliere is reason for believing that the same is the case with all other volcanoes, whatever may 

 be the nature of the surrounding formations ; that it is at great depths within or below the 

 solid crust of the globe that the volcanic agents as Avell as the bases of all their ejections 

 reside, and that it is there that lie concealed the causes which supply the flame attending the 

 eruptions and which produce the fluidity of the lavas." 



There is nothing in geology more celebrated or which longer prevailed than the system 

 of Werner : a universal and tranquil sea deposits, in vast masses, the primitive rocks, dis- 

 tinctly crystallized, in which at first silex predominates. The granite underlies all ; to this 

 succeeds gneiss, Avhich is but a granite beginning to foUate; by degrees clay gains tho 

 preponderance; schists of different sorts appear, &c. 



Werner never quitted Saxony, and it may be said of him that he was too hasty in con- 

 cluding that all the world was constituted like his own province. 



; IPuecli ov Puick, an old Aquitauiau word, signifying mountain. — Tr.] 



