32 MISSISSIPPI STATE GEOLOGICAL SURVEY [Bull. 
Clinging to limestone lcd<es are the following: 
Saxifraga Virginiensis Camptosorus rhizophyllus 
Heuchera villosa Asplenium angustifolium 
Heuchera Americana Cardamine Pennsylvanica 
Sedum ternatum Tris cristata. 
In the larger river bottoms exist remnants of what were 
once a good growth of white, water, and willow oaks, basket 
oak, sycamore, beech, river maple, black gum, sweet gum, and 
ceyprses. Hackberry, ash, redbud, great-leaved magnolia, sil- 
ver-bell, storax, paw-paw, and red birch are less useful, but 
equally handsome species. 
An inspection of this list shows a considerable number of 
trees, shrubs, and herbaceous species that are distinctly of 
Appalachian distribution, most of which are not distributed 
in the state south of this region. A few are found also on Pon- 
totoc Ridge, and occasionally in the northernmost tier of coun- 
ties to the westward. 
Northeastern Prairie Belt.—The boundaries of this region 
and its relationship to other divisions can best be understood 
by reference to the sketch map referred to above. 
The region has a gently rolling surface, and was originally 
prairies, having only here and there scattered patches of trees, 
except on the stream bottoms, which supported heavy growths 
cf timber. This Prairie Belt is now largely in eultiva- 
tion, but some timber remains in the bottoms. Within the last 
several years lands formerly in cultivation and now thrown 
out, show a strong tendency to grow up in trees, in some places 
the old field pine, in others thickets of shrubby oaks. 
The characteristic soil of the prairies, which is residual 
from the Cretaceous limestone, is a heavy, tenaceous, calcareous 
loamy clay, dark gray when dry, but almost black when wet. 
In much of the region a yellowish-brown loam soil prevails. 
This is a lighter soil than the typical prairie soil, less fertile, and 
usually supports a tree growth chiefly of post oak, black jack, 
and Spanish oak. The dark soil is the typical soil of the region 
and is naturally devoid of trees, except scattered clumps of 
