12 Tennessee Floka. 



of the soil, ajid inequality in distribution of atmospheric humidity 

 are, in our territory, sufiieiently potent to mark out four distinct 

 regions : 



I. The high crests of the Alleghany Mountains, formed of 

 Grauwake slates, gneiss, or mica schists, with an elevation of from 

 4,000 to 6,600 feet. Subalpine region. 



II. The western slopes 'of the Alleghanies and their outlying 

 spurs, and the Cumberland Mountains. Sandstones and slates. 

 Mountain flora. Elevation, from 2,000 to 4,000 feet. 



III. Valley flora, the lower division of which is coextensive with 

 the limestones (Silurian) of East and Middle Tennessee. Eleva- 



' tion, from 350 to 500 feet. The upper division, or highlands, has 

 siliceous and argillaceous soils, sometimes limestones of the sub- 

 carboniferous formation. Elevation, about 1,000 or 1,300 feet. The 

 former division is characterized through its cedar glades ; the latter 

 is the region of the oak barrens. 



IV. West Tennessee, situated between two powerful rivers, 

 with much level or only gently undulating surface, owes its pecul- 

 iarities to the abundance of swampy lands and predominantly 

 argillaceous soils, in connection with a more humid atmosphere. 



SUBALPINE REGION. 



The dividing line between the States of North Carolina and 

 Tennessee passes over and along the crest of the highest ridges 

 and peaks, known as the XJnaka, Great Smoky, Bald, and Frog 

 Mountains. Their average elevation is about 5,000 feet, but about 

 twenty-two summits are 6,000 feet or more. The highest stretch 

 lies between the French Broad Eiver and the Little Tennessee 

 River, with fifty-flve high points, eighteen of which are over 6,000 

 feet. Clingman's, Dome, by a few feet the highest, rises to the very 

 respectable altitude of 6,600 feet above tide water, according to the 

 measurements of Prof. Arnold Guiot,'of Princeton, N". J. (Vide 

 American Journal of Science, September, 185'^, and November, 

 1860.) Geologically they consist of Huronian schists and gneisses, 

 and in some spots, of Laurentian granites. 



Not one of these high crests presents a bleak crag, bare of . 

 vegetation, nor is there a timber line. Some are evenly timbered 

 throughout, others support only a scattered and stunted arboreal 

 growth, and some bear only a low shrubby or herbaceous vegeta- 

 tion. The absence of timber on the so-called " Balds " is perhaps 



