COROCORO COPPER DISTRICT OF BOLIVIA 39 



Vetas and at many localities from the city of Corocoro 

 north to the Pontezuelo River so that much larger collections 

 were secured. Whereas the collection made by Singewald 

 and Miller included 7 species, the new localities increased 

 the flora to 23 species. The Pliocene age of the Vetas is now 

 established beyond question. 



THE VETAS FLORA 



Representatives of 23 different species of plants have been 

 recognized from the plant-bearing layers of the Vetas. 

 Collections from the different horizons were kept separate 

 and these demonstrate that there was no change in the flora 

 during the interval of sedimentation, thus confirming the 

 a priori conclusion that the rate of accumulation of the 

 sediments was rapid and that the relatively great thickness of 

 this and the overlying Ramos and Desaguadero series does 

 not represent nearly as long an interval of time as com- 

 parable thicknesses of normal marine sediments would 

 indicate. Among these 23 plants some are determined much 

 more satisfactorily than others. Thus the Carpolithus may 

 represent one of several genera of plants with drupaceous 

 fruits ; the Rubiacites one of several existing genera of the 

 family Rubiaceae ; the reed which is not determined, even 

 generically, is unmistakably monocotyledonous. The Termi- 

 nalia is determined beyond any doubt, as are also the 

 Osteomeles, Polystichum, Ruprechtia, Dodonaea, and most 

 of thfe Leguminosae, although there may be some duplication 

 among the latter due to the variation and convergence 

 among the leaflets of this alliance. Taking them as they 

 stand and bearing in mind that nearly every form is repre- 

 sented by abundant and better preserved material from the 

 finer grained Potosi tuffs, it may be noted that they represent 

 a single fern, a single Gymnosperm, a single monocotyledon, 

 and 20 dicotyledons. The last represent 19 genera, 10 

 families and 6 orders. By far the most abundant of these 

 is the order Rosales with one member of the Rosaceae, 5 of 

 the Mimosaceae, and 4 each of the Caesalpiniaceae and 

 Papilionaceae. The last three, or leguminous families, thus 



