57° Valley of Copiapo. paet n. 



valley, one fragment of porphyrinic breccia-conglome- 

 rate, exactly like those great masses met with in the 

 more southern parts of Chile. 



Finally, I must observe, that though I have de- 

 scribed between the town of Copiapo and the western 

 flank of the main Cordillera seven or eight axes of 

 elevation, extending nearly north and south, it must 

 not be supposed that they all run continuously for 

 great distances. As was stated to be the case in our 

 sections across the Cordillera of Central Chile, so here 

 most of the lines of elevation, with the exception of 

 the first, third, and fifth, are very short. The stratifi- 

 cation is everywhere disturbed and intricate ; nowhere 

 have I seen more numerous faults and dikes. The 

 whole district, from the sea to the Cordillera, is more 

 or less metalliferous; and I heard of gold, silver, 

 copper, lead, mercury, and iron veins. The metamor- 

 phic action, even in the lower strata, has certainly 

 been far less here than in Central Chile. 



Valley of the Despoblado. — This great barren valley, 

 which has already been alluded to, enters the main 

 valley of Copiapo a little above the town : it runs at 

 first northerly, then NE , and more easterly into the 

 Cordillera ; I followed its dreary course to the foot of 

 the first main ridge. I will not give a detailed section, 

 because it would be essentially similar to that already 

 given, and because the stratification is exceedingly 

 complicated. After leaving the plutonic hills near the 

 town, I met first, as in the main valley, with the gypseous 

 formation, having the same diversified character as be- 

 fore, and soon afterwards with masses of porphyritic 

 conglomerate, about 1,000 feet in thickness. In the 

 lower part of this formation there were very thick beds 

 composed of fragments of clay-stone porphyries, both 

 angular and rounded, with the smaller ones partially 



