240 EXPERIMENTS ON METAMORPHISM AND 



Beaumont made known how recent is the elevation of the greatest 

 chain of mountains in Europe. These results, at the same time so 

 novel and so grand, deeply impressed all minds, and gave an extra- 

 ordinary impulse to geological studies. 



Appointed at this time to the chair of geology at the School of 

 Mines, Elie de Beaumont thenceforth powerfully contributed to spread 

 the geological doctrines on which he had conferred so many ac- 

 quisitions, especially through observations made by himself in the 

 Alps, or derived from the memoirs of Maccullock on Scotland. The 

 comparison by which he summed up the gradual transition of sedi- 

 mentary to crystalline rocks, likening it to "'the physical structure of 

 a brand half burned, in which we can trace the ligneous fibres far 

 beyond those points which still preserve the natural characters of 

 wood," is as clear as it is profound.* He showed, besides, that lime- 

 stones and other rocks might have crystallized without having been 

 fused, just as occurs with a bar of iron long heated .below its point of 



softening, t 



When Elie de Beaumont, discovered a few years after, in the 

 midst of rOisans:|: granitic rocks jutting out above the Jurassic lime- 

 stone which had become saccharoidal, and in contact with which they 

 have produced little veins of metallic minerals, while it modelled itself 

 exactly to the undulated contours of the surface, he still more en- 

 larged the field of metamorphic phenomena. 



Facts exactly like those which had just been discovered in the Alps 

 were recognized in the region of the Apennines. The marble of 

 Carara, and the mass of talcose and micaceous schist which accom- 

 pany it, were, b}'- the observations of Pasini, Pareto, Guidoni, and 

 Paul Savi,|| which were confirmed by Hoffman, § classed in the 

 secondary Jurassic or cretaceous formations. Tuscany had furnished 

 to Savi, as far back as 1829, many remarkable examples of vari- 

 ous alterations in the neighborhood of serpentine. The Pyrenees 

 also revealed at the same epoch facts which confirmed and extended 

 these new ideas. 



In 1819 Palassou, an observer as judicious as modest, after having 

 for four years explored these mountains, anuounced with certainty 

 that no primitive limestones existed in this chain, and that beds of 

 limestone as crystalline as the marble of Paros alternated wdth fossil- 

 iferous beds, and sometimes even contained them.l 



^ Annales des Sciences Noturelles, vol. xv; p. 3()2-372. 



■\ Avnales des Mines, 3d series, vol. v, p. 61. 



j Faits pour servir k I'histoire des Montagues de I'Oisans. — {An7iales des Mines, 3d series, 

 vol. v, p. 1.) 



II The works of these geologists have been reviewed by M. Boue iu the Bulletin de la 

 Soctete Geologique de France, vol. iii, p. 42. 



§ Entdechliungen iiber den Marmor von Carrara. — Jahrbuch, p. 102, 1833. Gebirgs Ver- 

 haltnissc der Grafschaft Carrara. — Jahrbuch, p. 563, 1834. Karsten's Archiv, vol. 6, p. 229. 



We ought here to call to mind that M. de Blaiuville had at this time previously discov- 

 ered in the polished specimens of this last rock unequivocal vestiges of polypiers. 



^ Memoir on the limestones of the Pyrenees. — {Suites des M6moires de Palassou. Pau, 1819.) 



De Charpentier had also noticed like alterations in his important work on the Py- 

 renees, 182.?. 



