128 Geology of South America. 



bones of the mammifera, belonging to species which have been 

 destroyed. 



The appearance of the trachytic rocks of which the highest 

 summits of the Cordilleras of Chili and Peru are composed, 

 does not, however, seem to have been the last of the great 

 geological movements of which South America has been the 

 theatre. This eruption seems to be connected with the origin 

 of the Pampean loam, and this formation is covered, as we have 

 seen above, by other deposits, which indicate another and more 

 modern great event. This last great event can only be sought 

 for in the first outburst of the American volcanoes now in ac- 

 tivity, which, up to the period just mentioned, had not yet 

 commenced the series of their eruptions. The long line of 

 the volcanoes of Chili, ranged in accordance with the axis of 

 the trachytic zone, is the extreme link of that great zig-zag 

 volcanic chain, which, resting on the half of a great circle of 

 the earth, described from the republic of Bolivia to the Birman 

 empire, marks the limits of the great mass of the American 

 and Asiatic Continents, and of the vast oceanic extent of the 

 Pacific. It was, without doubt, a memorable day in the his- 

 tory of the inhabitants of the globe, and perhaps even in the 

 history of the human race, when that immense volcanic battery, 

 which does not include less than two hundred and seventy 

 principal orifices, was opened for the first time. Perhaps the 

 traditions of a universal deluge are connected with this great 

 events rvhich could not fail to be a fearful disaster. The au- 

 thor is favourable to this opinion, which had already been pre- 

 viously proposed, but only as an hypothesis. He adduces, in 

 support of it, many facts which, even although they should 

 remain isolated, seem to us deserving of the attention of geo- 

 logists. 



We have already quoted the observations according to which 

 M. D'Orbigny concludes that the recent elevated shells on the 

 shores of the Atlantic and the Pacific could not have been 

 raised by a slow action, but by a sudden movement. These 

 remarks, together with the facts also noticed in relation to 

 the beds of conchillas of the Pampas, to the shells of Monte 

 Video and of Patagonia, and to all those of the coast of the 



