xlviii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



again, as M. Favre has demonstrated, in the sea of the Jurassic 

 period, and they were accompanied and followed by metamorphic 

 action, occasioned by gaseous emanations. The tuffs and trap dikes 

 of Monte Bolca and the Vicentine show that other volcanic eruptions 

 poured out lava and ejected scoriae into the waters of the eocene sea. 

 Again, after this period, the protrusion, if not the formation, of the 

 talcose granite, or protogene of the central nucleus of the Alps, oc- 

 curred. The upheaval of nearly the whole mountain mass, from the 

 waters of the eocene sea to an elevation of more than two miles 

 above its level, happened subsequently to the deposition of all the 

 nummulitic beds and the flysch. These latter deposits, thousands 

 of feet in thickness, shared, after the commencement of the tertiary 

 period, in all the movements, whether slow or convulsive, to which 

 the Alpine rocks owe their curvatures, dislocations, and vertical or 

 lateral displacement. The grand sinking-down of the nagelflue or 

 conglomerate of the molasse, more than a -mile vertically, belongs 

 again to a still later period, which did not begin till all the eocene 

 movements had terminated, and was due to a gradual subsidence 

 along the whole northern flank of the chain. At a still more modern 

 sera, the entire upheaval of the same molasse took place, so that it 

 reached at length its present altitude of 3000 or 4000 feet above the 

 sea. Nor did the uplifting agency cease here, for it contuiued till 

 the newer or subapennine tertiary beds were made to emerge. There 

 are proofs indeed of the relative level of sea and land having been 

 modified even after the erratic blocks were conveyed to their present 

 sites, or subsequently to the glacial period of Northern Europe. 



This assignment to a great number of distinct and separate periods 

 of the work done by the moving and disturbing powers, is by no 

 means the result of the study of the Alps exclusively. In other moun- 

 tain-ranges it is now ascertained that the upheaving and depressing 

 forces have been propagated in succession along the same parallel 

 zones of country ; and M. Elie de Beaumont has frankly confessed 

 that he was in error when he first pronounced the Pyrenees to be a 

 chain due to a single upthrow, "un seul jet," or "une chaine elevee 

 en une seule fois." He and M. Dufrenoy now go so far as to 

 agree with M. Durocher, that in the Pyrenean chain, in spite of the 

 general unity and simplicity of its structure, six, if not seven systems 



