4O1 GEOLOGY APPLIED TO 



stein, which are frequent towards the west, have not yet 

 been seen in Venezuela; but it maybe also observed that 

 in the system of secondary rocks of the old continent, 

 muschelkalk and quadersandstein are not always clearly 

 developed, and are often, by the frequency of their marls, 

 confounded with the lower layers of Jura limestone. 

 The muschelkalk is almost a lias with encrinites; and 

 quadersandstein (for there are doubtless many above the 

 lias or limestone with gryphites) seems to me to represent 

 the arenaceous layers of the lower shelves of Jura lime- 

 stone. 



I have thought it right to give at some length this 

 geologic description of South America, not only on 

 account of the novel interest which the study of the forma- 

 tions in the equinoctial regions is calculated to excite, but 

 also on account of the honourable efforts which have 

 recently been made in Europe to verify and extend the 

 working of the mines in the Cordilleras of Columbia, 

 Mexico, Chile, and Buenos Ayres. Vast sums of money 

 have been invested for the attainment of this useful end. 

 In proportion as public confidence has enlarged and con- 

 solidated those enterprises, from which both continents may 

 derive solid advantage, it becomes the duty of persons 

 who have acquired a local knowledge of these countries to 

 publish information calculated to create a just apprecia- 

 tion of the relative wealth and position of the mines in 

 different parts of Spanish America. The success of a 

 company for the working of mines, and that of works 

 undertaken by the order of free governments, is far from 

 depending solely on the improvement of the machines em- 

 ployed for draining off the water, and extracting the 

 mineral, on the regular and economical distribution of the 

 subterraneous works, or the improvements in preparation, 

 amalgamation, and melting: success depends also on a 

 thorough knowledge of the different superposed strata, 

 The practice of the science of mining is closely linked with 

 the progress of geology; and it would be easy to prove 

 that many millions of piastres have been rashly expended 

 in South America, from complete ignorance of the nature of 

 the formations, and the position of the rocks, in directing 



