K> o s t e I s i a 33 



odd, for it would be expected that the 

 top of the slope would be the driest 

 place of all. It is so in most hills. 

 The mesas, however, have flat tops, 

 on which the spring snow lasts for a 

 long time. As it slowly melts, the 

 water trickles down the sides and is 

 absorbed by the soil not far from the 

 top of the slope. There is sufficient 

 moisture on the north slope to permit 

 the growth of shrubs for some distance 

 away from the foothills. In general the 

 tops and the north sides of the mesas 

 ave the same plants. At the eastern 

 end of mesas the north and south 

 slopes are quite gentle. Here the 

 plants are alike on the slopes and on 

 the top which becomes the east slope 

 at the terminus of the mesa. All the 

 plants now are species of the plains. 

 The flora of the mesas is a com- 

 plex of mountain and plain species. 



