52 



served, as what forms the upper stratum in one 

 mountain, I have discovered to be the inferior in 

 another. They in general, however, preserve a 

 degree of regularity in their inclination, which is 

 from south to north, a little tending towards the 

 west, corresponding with the relative situation 

 of the ocean, whose currents are from south to 

 north. 



Notwithstanding these mountains in general 

 are composed of various strata, there are several 

 that are uniform ; some are entirely calcareous, 

 others are of gypsum, of granite, of freestone, of 

 quartz, of basaltes, of lava, and other volcanic 

 substances; while, as Ulloa justly observes, 

 some appear to consist entirely of shells, scarcely, 

 if at all, decomposed. But all these homo- 

 geneous mountains are barren, and produce 

 only a few languid shrubs, while the stratified 

 mountains, which are covered with a depth of 

 cultivable soil, are always clothed with a plen- 

 tiful and vigorous vegetation. 



The exterior of the stratified mountains like" 

 wise furnishes a proof of their formation by 

 the ocean. Their bases are almost always 

 very extensive, heightening progressively and 

 forming various valleys, whose inflections 

 are correspondent to the undulation of the 

 Avavcs. On examining the valleys, their orp:ani- 

 zation is readily p<'iceived to be the same with 

 iiint of the stratified mountains: similar ma- 



