156 STUDIES IN GEOLOGY, No. 4 



ditions more like those found at the present time east ot 

 Cochabamba at elevations below 6,000 feet. From a consid- 

 eration of all of the available facts I conclude that the Pislly- 

 pampa flora is of Pliocene age and probably slightly older 

 than that found at Potosi. The difference in age I regard 

 as slight, and the observed differences in the two floras are 

 those that can be almost entirely explained by slight differ- 

 ences in altitude and somewhat greater differences in humid- 

 ity. 



A flora of about the same age as that of Pisllypampa is 

 known from several localities in the state of Bahia, Brazil. 

 This was partially worked up by Ettingshausen, but never 

 completed. 7 Considerable collections made from these local- 

 ities by Branner and others are being elaborated by Hollick 

 and the present writer, but this work has not progressed far 

 enough for discussion, although there are some similarities 

 shown to the Pisllypampa flora despite their geographical 

 remoteness. 



AMOUNT OF ANDEAN UPLIFT INDICATED 



If the Pliocene age of the Pisllypampa flora is established, 

 as I regard it, and it can be determined within reasonably 

 accurate limits what is the upper limit of range of an almost 

 identical modern plant assemblage, the result will be a fairly 

 reliable measure of the amount of uplift to the present alti- 

 tude of 1 1, 800 feet since some time in the Pliocene. 



A consideration of the accompanying table shows that 

 altitudinal information is lacking in the case of eight of the 

 twenty species, and this information is inexact in the case of 

 six additional forms. There are, however, no forms repre- 

 sented which normally reach great altitudes, except the cas- 

 sias which could equally well represent low bushes of high 

 altitudes or bushes of arid climatic conditions or trees of 



7 Krasser, F., Sitz. k. k. Akad. Wiss. Wien, Bd. 112, pp. 852-860, 

 1903. 



