2A. PLATEAU REGION. 



49 



from crevices on its under side, and often a few small 

 springs at its base as well. Some of the ledges overhang 

 so far that part of the roof of the "house" back of the 

 edge has become loosened by the action of water on joint- 

 planes and fallen in, leaving the outer edge as a natural 

 bridge. A beautiful example of this can be seen near 

 Natural Bridge station in Winston County. The bridge 

 there has a span of about 80 feet and a width of about 

 20, and is of very graceful proportions, being a very flat 

 arch with a thickness of only three or four feet in the 

 middle. (See figure 10.) 



Climate.— None of the present weather stations with- 

 in this region have been established long enough to give 

 accurate climatic data, but the climate of the plateau 

 probably does not differ much from that of the Tennes- 

 see valley, in average annual temperature at least. On 

 account of its elevated position it may be a little more 

 exempt from early and late frosts, and thus have a 

 slightly longer growing season. 



Forest types. — The principal forest type of the plateau 

 region is the dry oak and pine woods of the compara- 

 tively level loamy uplands. Much more limited in ex- 

 tent, but perhaps equally rich in species, are the richer 

 woods of ravines and bluffs, sufficiently protected from 

 fire and evaporation for the growth of beech, sweet gum, 

 poplar, etc., and the swamps and banks of creeks and 

 branches. Fire is moderately frequent in the level open 

 woods, especially in the limited areas where long-leaf 

 pine grows. 



LIST OF TREES. 



4 G 



