Geology of South America. 129 



Pacific, lead him to admit a sudden general elevation of the 

 whole coast, which gave rise to the present configuration of 

 the Continent. This last movement of the American surface, 

 which coincided with the first outburst of the volcanoes, would 

 produce a commotion in the adjacent seas, whose waters rising 

 above the crests of the mountains, hollowed them out, broke 

 up the surface at all heights, and transported vast masses of 

 alluvial matter into the plains. 



The traditions of a deluge, which have been met with 

 among most of the American nations, may be only a souvenir 

 of this last revolution. The discovery made by M. D'Orbigny 

 of the remains of human industry in the alluvium of the plains 

 of Moxos, on the banks of the Rio Securi, is an additional 

 reason for this conjecture* As it is at least evident that 

 that event was posterior to the existence of the present marine 

 fauna, M. D'Orbigny has considered himself entitled to term 

 its products diluvial formations. 



In conclusion, it results from the investigations of M. D'Or- 

 bigny, that the new continent has been formed, like the old 

 one, by the successive soulevements of the difi'erent systems of 

 mountains which traverse the surface ; that these systems be- 

 come more and more extended in proportion as their origin 

 approaches the present period ; and that the reliefs resulting 

 from these different systems have been successively added 

 to one another, advancing generally from the east to the 

 west. Thus the most ancient prominences presented by the 

 American Continent appear to have had their origin in the 

 eastern region of Brazil, after the epoch of the formation of 

 the gneiss. The transition formations next made their ap- 

 pearance to the west, and increased the original continent by 

 the amount of the whole Itacolumian system. The carboni- 

 ferous formations, to the west of the two others, form a part 

 of a new appendage composed of the Chiquitian system. The 

 triassic formations, to the west of the three first systems 

 have been upraised in the Bolivian system, a surface of much 

 greater extent than the others. Up to that period America 

 had been elongated from the east to the west. The creta- 

 ceous formations ceased to be deposited, and the Cordillera, still 



VOL. XXXVII. NO. LXXIII. ^JULY 1844. I 



