Prairies, Flats, and Barrens in Southern Illinois. 393 
The “barrens,” as the term is understood in the district to 
which I have reference, are hills covered with a dense growth of 
tall grasses, without or with only scattering eeu’ trees. The 
progressing cultivation has however changed their aspect con- 
siderably, and large portions of them now te a deuse growth 
of young timber. ‘They occupy that portion of the upland the 
surface of which is too uneven for prairies and flats, — gently 
undulating, i sharply rolling or even modera tely broke: 
Their subsoil is the same white sandy loam mentioned before; but 
their saxiscnoeedgoictees affords a complete drainage, and they 
have therefore sustained a better vegetation and have formed 
some inches of a good soil considerably charged with humus. 
That of the sharper ridges is however apt to wash down into the 
the hollows, sind | is therefore generally shallow, while it has ac- 
cumulated in the lower places. Their subsoil is frequently, but 
erroneously, called yellow clay; it is yellow only on exposed sur- 
aces, on cuts in the roads, and similar places, where the iron of 
the soil, which elsewhere is all concentrated in smal] grains of 
dark brown color, is more diffused over the surface and colors the 
white material yellowish. The drainage of the substrata seems 
also to be perfect, and the underlying porous sandstones not 
less packed than that of the flats, and the ee ine ciples 
of their earlier growth, have progressed farther’ in their devel- 
appears to have been due to the encroachment of the grasses, 
which, being well developed in the eriy e prairies, a no 
timber could grow, spread out and took possession e bar- 
rens. Other lands very similar to te barrens, in teperd to soil 
and situation, are timbered with post-oak forest. The annual 
>» 
essary 
growth of timber. In some rab settled sediatibowlsdods we still 
find the barrens covered with rank coarse grass, but generally 
a dense growth of small oak is springing up spontaneously, 
and at many places very vigorously, nen ghergs fl . the “sae 
inhabited districts. At some points we find in 
single large post oak, as we do on the date: generally the vouig 
growth on the poorer ridges is post oak (Q. ob tusiloba) and blac 
oak (Q. tinctoria) with some blackjack (Q. nigra), in the hollows 
and sumach, on the finer rolling lands post oak, b 
