393 



of journeying in the Andes, have enabled me to 

 rectify my first views, and to extend an inves- 

 tigation which, on account of its novelty, had 

 been favorably received. The mineralogical 

 descriptions of every rock have been given in 

 the preceding chapters ; it now only remains to 

 collect the scattered materials, and mark the 

 pages where the detail of the observations are 

 found. That the most remarkable geognostic 

 relations may be more easily seized, I shall treat 

 in an aphoristic manner, in different sections, 

 the configuration of the soil, the general divi- 

 sion of the land, the direction and inclination 

 of the beds, and the nature of the primitive, in- 

 termediary, secondary, and tertiary rocks. The 

 nomenclature I employ in this memoir, is that 

 of which I recently stated the principles in a 

 work on general geognosy *. 



SECTION I. 



Configuration of the Country. — Inequalities of 

 the Soil. — Chains and groups of Mountains. — 

 Ridges of Partition. — Plains or Llanos. 



South America is one of those great triangu- 

 lar masses which form the three continental 



* See my Essay on the position of Rocks in the two Hemi- 

 spheres, 1823. 



