President of the Geological Society for 1850. 19 



able of late years to bring to light any new facts in support 

 of their favourite doctrine. On the contrary, if I mistake 

 not, they have been more and more compelled to assign the 

 time during which the disturbing power was exerted to a 

 succession of distinct geological periods, in some of which the 

 force must have operated very slowly, while in other cases 

 where it was sudden it may probably have been intermittent, 

 and consisted, as in ordinary volcanic action, of a repetition 

 of shocks or explosions of moderate intensity. In illustra- 

 tion of these principles, I may first mention that some of the 

 volcanic eruptions of the Alps, which produced the porphyry 

 called melaphyre, broke out again and again, as M. Favre 

 has demonstrated, in the sea of the Jurassic period, and they 

 were accompanied and followed by metamorphic action, occa- 

 sioned 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, occurred. 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 num- 

 mulitic 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 con- 

 vulsive, to which the Alpine rocks owe their curvatures, dis- 

 locations, 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 pe- 

 riod, 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 

 era, 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 continued till the newer or subapennine tertiary beds 

 were made to emerge. There are proofs indeed of the rela- 

 tive level of sea and land having been modified even after the 



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