43 



rally a kind of whetstone, of a reddish colour and 

 a sandy grain, sometimes a quartzeoiis sand, or a 

 compact dark grey sandstone ; this is succeeded by 

 layers of clay, marie, various kinds of marble, schis- 

 tus, spar, gypsum and coal ; beneath the whole are 

 found veins of ore, ocher, quartz, granite, porphy- 

 ry, sand, and rocks of various degrees of hardness. 



The disposition of the strata varies very conside- 

 rably in different places, and in these derangements 

 the laws of gravitation are seldom observed, as what 

 forms the upper stratum in one mountain I have dis- 

 covered to be the inferior in another. They in gen- 

 eral, 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 UUoa justly observes, some appear to con- 

 sist entirely of shells, scarcely, if at all, decompos- 

 ed. But all these homogeneous 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 

 plentiful and vigorous vegetation. 



The exterior of the stratified mountains likewise 

 furnishes a proof of their formation by the ocean. 

 Their bases are almost always very extensive, height^ 



