1879.] Teras in its Geognostic and Agricultural Aspect: 377 
valleys in the south, presenting steep and rocky entrances, rarely 
widening into fertile plains. All the principal rivers of Texas rise 
in this division, which is but sparsely settled and but imperfectly 
explored and known. 
If now we take under review the formation and composition of 
the soil of these different parts of the State, the following will be 
the result as to their fertility and products: 
In general we distinguish three different kind of soils—sand, 
clay and limestone—in the first, sand or silica predominates, in 
the second, clay, in the third, carbonate of lime. Neither of these 
constituents alone is sufficient to produce a vigorous growth of 
plants; that this is the case with sand is proved by the great des- 
erts of Asia and. Africa. When sand constitutes more than nine- 
tenths of the soil, vegetation cannot flourish ; yet all soils require 
a certain proportion of sand, because every plant needs some sand 
for its growth; for cereals especially this element is indispen- 
sable. The clay soil has also its defect, it is too tenacious, so 
that the roots cannot spread out; it retains water too long, and 
when it dries it hardens into tough lumps; it has, therefore, pre- 
cisely the opposite faults of sand, wherefore a proper intermix- 
ture of the two proves advantageous. A soil consisting solely of 
lime varies too violently in moisture and dryness; lime is, how- 
ever, as indispensable for the nutriment of plants as sand, so 
that mixed in proper proportions with sand and clay, it proves 
itself highly advantageous in every respect; hence soils com- 
posed of sand, clay and lime are, without doubt, the most fertile. 
Now, as regards Texas particularly, its sandy soil was mainiy 
derived from the sandstone of the tertiary period, whilst its clay 
and lime soil deposits came from the tertiary and Mesozoic ages. 
The soil of the Lowlands is, through the accumulation of 
sand, clay and lime, brought into a mixture very beneficial to 
cultivation, but owing to the presence of salt, and still more 
to its level surface, which hinders the discharge of water, it is 
not adapted to every kind of cultivation, wherefore wheat can- 
not be raised, whilst Indian corn,.sugar-cane and cotton suc- 
ceed admirably. The entire Lowlands are not yet extensively cul- 
tivated, and its more general culture depends upon a thorough sys- 
tem of drainage. The condition of the soil is everywhere the 
Same, neither stones nor rocks are to be seen. 
-In the cscs igs we find the sandstone, ssl the sand ane 
