THE "barrens' of KENTUCKY AND TENNESSEE. 



489 



added columns for sbowing the order of frequency of the several species, 

 the more numerous being marked 1, the next 2, and so on to the end. 

 But in doing this, there occasionally occurs the same proportion in two 

 or more species, and in this case we have assigned tbe same numeral 

 order to each, designating by a star the duplicate or other number of 

 species that belong to this numerical order. 



Percentage and relative order of frequency of timber-trees in Eastern Kenttickij. 



* More than one having this number. 



The '■'■'barrens^'' of Kentuclcy and Tennessee. 



Extensive tracts of irregular form occurred in these States, when first 

 explored, which were quite destitute of timber, or the remains of forests 

 in the way of fallen trunks or stumps, excepting here and there a knoll 

 of timber, on gravelly soil. They were in fact ijrairies, and apparently 

 caused by the annual burning of the herbage, as practiced by the In- 

 dians, either to drive game, to encourage the growth of fresh grass for 

 deer, or perhaps to destroy the lurking-places of enemies, or to prevent 

 accidents from unexpected fires. These lands have proved highly pro- 

 ductive under cultivation, and since the fires have been prevented, they 

 have grown up in timber, but not so varied in kind as that found in 

 adjacent native forests, nor as a general thing so valuable for use. This 

 rapid restoration of forests in these States, and in parts of Ohio and 

 Indiana, while the process is slow in Illinois, has been thought to be 

 due to a more recent origin, and the endurance of living seeds in the 

 eoil.^ It has been observed that the area of these old barrens is 

 somewhat limited to the surface area of the conglomerates underlying 

 the coal formation of these States.^ This subject is being studied in 

 connection with the geological survey of Kentucky, and tbe details are 



1 Prof. N. S. Shaler, Geological Survey of Kentucky, part'll, vol. I, 2d ser., p. 4. 

 *Mr. John B. Proctor, Assistant of Kentucky Survey. 



