580 Metalliferous Veins. part n. 



beds, most of the rocks, as already remarked, present 

 a striking general resemblance with the upper parts of 

 the gypseous or cretaceo-oolitic formation of Chile. 



Metalliferous Veins. 



I have only a few remarks to make on this subject: 

 in nine mining districts, some of them of considerable 

 extent, which I visited in Central Chile, I found the 

 principal veins running from between [N. and NW.] 

 to [S. and SE.] : ! in some other places, however, their 

 course appeared quite irregular, as is said to be gene- 

 rally the case in the whole valley of Copiapo : at Tam- 

 billos, south of Coquimbo, I saw one large copper vein 

 extending east and west. It is worthy of notice, that 

 the foliation of the gneiss and mica-slate, and the 

 cleavage of the altered clay-slate, where such rocks 

 occur, certainly tend to run like the metalliferous 

 veins, though often irregularly, in a direction a little 

 westward of north. At Taquil, I observed that the prin- 

 cipal auriferous veins ran nearly parallel to the grain or 

 imperfect cleavage of the surrounding granitic rocks. 



gypsum, and coal associated together. The strata include veins of 

 quartz, carbonate of lime, and iron pyrites : they have been dislocated 

 by an injected mass of greenish-brown feldspathic trap. 



Not only is salt abundant on the extreme western limits of the 

 district between the Cordillera and the Pacific, but, according to 

 Helms, it is found in the outl}ing low hills on the eastern flank of the 

 Cordillera. These facts appear to me opposed to the theory, that 

 rock-salt is due to the sinking of water, charged with salt, in medi- 

 terranean spaces of the ocean. The general character of the geology 

 of these countries would rather lead to the opinion, that its origin 

 is in some way connected with volcanic heat at the bottom of the 

 sea : see on this subject, Sir R. Murchison's Anniversary Address to 

 Geolog. Soc. 1843, p. 65. 



1 These mining districts are Taquil near Xancagua, where the 

 direction of the chief veins, to which only in all cases I refer, is 

 north and south ; in the Uspallata range, the prevailing line is NNW. 

 and SSE. ; in the C. de Prado, it is HTNW. and SSE. ; near Illapel, it 

 is X. by W. and S. by E. ; at Los Hornos, the direction varies from 

 between [X. and XW.] to [S. and SE]. ; at the C. de los Hornos 

 (farther northward), it is XXW. and SSE. ; at Panuncillo, it is NNW. 

 and SSE. : and, lastly, at Arqueros, the direction is NW. and SE. 



