- 
378 Texas in its Geognostic and Agricultural Aspect. [June, 
clay deposits of the tertiary formation in vast extent, and the 
peculiarity of it is that these places are, throughout, covered with 
forests, indeed we may safely conclude that wherever extensive 
forests are found in elevated positions, they arise from a tertiary 
foundation. Thus the whole forest-clad parts of Eastern Texas, 
from Red river down to the sea-coast, consist of these formations, 
the upper and lower cross timbers of North-western Texas, like 
the post-oak forests situated in the middle and southern, rest 
throughout upon tertiary formations. Since now the soil there, 
mainly through the influence of the glacial era, was derived from 
sandstone and sandy-clay deposits, it is, therefore, less adapted to 
the cultivation of plants, having obtained a large share at the 
same time through a considerable proportion of iron, as we 
shall see later; yet along creeks and rivers are found here and 
there. places fit for cultivation. In the first years of culture, 
plants flourish generally quite well; but the strength of the soil 
is soon exhausted, which has strikingly exhibited itself in parts 
of Louisiana bordering on Texas, this side of Red river. This 
region has been for a long time thoroughly cultivated, and at this 
time has only two-thirds of its former extent under culture. 
Wheat does not succeed in this soil, and cotton is mostly only 
one to two feet high; corn.is weak in the stalk and the ears are 
small; fruit-trees alone flourish there, viz: peaches and apples, 
since these trees are enabled to send their roots deep into the 
ground, Pines, which grow best in sandy regions, diffuse them- 
selves to a great extent through the forests. Since then, by 
means of forests, we can decide the tertiary foundation of the soil, 
so in the same way we may state that open prairies and places 
covered with mesquite trees, indicate that the soil rests upon 
secondary formations, There again the soil is formed of sand, 
clay and lime, through the operation of the glacial era, and min- 
gled together in so advantageous a manner that it presents all 
those conditions on which depends the perfect development of all 
cultivated plants. This division embraces that part of Texas 
which promises to become so large a source of food such as 
no other State of the Union possesses, even such as can be found 
in few portions of any continent. Again, in this same division is 
that region of peculiar importance in which naked rocks appear 
on the surface, neither to a small nor great extent immediately 
_ after the tillable ground has been broken up by other causes. 
i 
