46 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
Insoluble matter... 
Soluble silica. 
Potash. 
Soda. 
Lime. 
Magnesia. 
Manganese . 
Iron. 
Alumina. 
Phosphoric acid .. 
Sulphuric acid 
Water and organic 
36* 
96.360 
1.176 
.209 
.058 
.038 
.206 
.081 
.497 
.671 
.121 
.030 
.889 
* Cotton Production, Tenth Census, p. 29. 
100.336 
Residual Soils of the Central Basin. 
Tbe Basin Region may be roughly defined as that portion of the State 
between the Upper Cross Timbers on the east and the Guadalupe moun¬ 
tains on the west, and lying north of 31st parallel of latitude. The De¬ 
nuded areas are underlaid by rocks of the Carboniferous and Permian, 
while the dividing plateaus are Cretaceous, Tertiary, and later. 
The soils derived from these various formations of course differ greatly. 
The soils of the Denuded areas comprise both marls and loams; the Cre¬ 
taceous plateaus usually yield only thin soils suitable for pasturage; and 
the later plateaus furnish fertile loamy soils. 
This region lies for the most part west of the humid belt, in the sub- 
humid and dry region. With proper seasons the productiveness of the 
soils is all that can be desired, but these are not always certain. For this 
reason preparation is now being made for irrigation both from streams 
and storage reservoirs, and there is every reason to believe that the results 
will be of the greatest benefit. 
, soil of the denuded areas. 
Coal Measures.— Much of the area over which the rocks of the Coal 
Measures and Permian are now exposed was formerly covered also by the 
rocks of the Cretaceous formation. In their disintegration and removal 
they have left some imprint on the underlying beds, and, in places, have 
helped to make the soils what we now find them. 
The rocks of the Coal Measures being principally sands and clays with 
some limestones, naturally yield a greater proportion of loamy soils, with 
here and there a belt of sand or marl. The admixture of limy material 
from the Cretaceous has given a marly character even to some of the 
soils derived from the alternating clays and sands of this district. 
