MODE II. CLAY SLATK. 



at Alcacado clay slate, interspersed with masses 

 of granite ; and afterwards red sand-stone on the 

 clay slate. They afterwards alternate, and the 

 slate is covered with thin moss. 



The rich city of La Paz is built at the bottom 

 of the highest part of the Andes, covered with 

 everlasting snow. In a fragment of the rock, 

 being a glutenite of yellow clay and rounded 

 flints, lumps of pure gold were found, weighing 

 from two to twenty pounds. Puno, which is 

 also one of the highest parts of the Andes, pre- 

 sents mountains of fine clay slate, abounding in 

 rich ores of gold and silver. 



Passing through Cuzco he arrives at Carretas. 

 " The base of argillaceous slate is covered with 

 an alluvial superstratum, which consists of marl, 

 gypsum, lime-stone, sand, a large quantity of 

 rock salt, and of fragments of porphyry, &c. 

 in which pure silver and rich silver ores* occur 

 in abundance. There are few instances in 

 Europe of such mountains so generally abound- 

 ing with the precious metals, or their ores, as in 

 this quarter of the globe. The whole ridge ap- 

 pears to be full of alluvial veins of heavy silver 

 ores, in which pieces of pure silver, solid cop- 

 per, and lead ore, occur,, intermixed with a 

 great quantity of white silver ore, and capillary 

 virgin silver. Thirty-six miles before we reach 



