E. T. DtfMBLE-THE SOILS OP TEXAS. 
37 
8* 
9* 
lot 
Insoluble matter. 
93.700 
71.750 
o o 
l- o 
T—t GO 
o 
Soluble silica. 
2.140 
12.110 
Potash . 
.008 
.062 
Soda. 
.144 
.240 
Lime . 
.180 
.490 
.600 
Magnesia. 
.080 
.460 
.550 
Manganese. 
.090 
.060 
Iron. . 
.490 
1.900 
2.990 
Alumina . 
.900 
6.460 
8.330 
Phosphoric acid. 
.011 
.008 
.083 
Sulphuric acid. 
.106 
Carbonic acid. 
.130 
.090 
.470 
Water. 
1 .280 
5.460 
5.S20 
Organic and volatile. 
.750 
.560 
3.940 
99.903 
99.650 
99.859 
* Fourth Annual Report, Geol. Sur. Tex., p. 25. 
t Bulletin 25, Tex. Ag. Ex. Sta., p. 269. 
Marine Belt.— This belt, with its interbedded sands and clays, green¬ 
sands and iron ore, is one of the most extensive of the belts of the Ter¬ 
tiary plain. While it shrinks to a narrow area in the vicinity of the 
Colorado river, it broadens to the east and west, until it attains a width 
of not less than sixty miles. 
The alternating sands and clays give rise to red sandy, red clayey, or 
loamy soils of different characters; the greensand beds furnish mulatto, 
or dark brownish red, or black sandy loams; and overlying the iron ore 
ridges are gray sandy soils, which are the great fruit soils of the region. 
The red sandy soils are usually deficient in potash and sometimes in 
phosphoric acid, elements which are found in the greensand marls which 
occur in connection with them, and therefore present the easiest means of 
supplying these essential elements of fertility to the soils requiring them. 
These elements are largely derived from the grains of glauconite, which 
have their origin in the wealth of minute animal life with which the 
waters of that portion of the Tertiary teemed. 
West of the Colorado these soils appear as alternate belts of chocolate 
loam with a growth of mesquite and live oak, and fine brown sands or 
sandy loams with blackjack and hickory. The loams vary from sandy 
to clayey with the beds from which they are derived. Colors vary from 
gray to chocolate. Some of the brown sandy loams form prairies; at 
other places there is found on them a thick growth of cactus and mesquite 
with a few scattering live oaks. The red sandy soils of the eastern por¬ 
tion of the State occur here also, but in smaller areas. 
The character of the soils of the Marine belt are represented in the 
analyses by Nos. 11 and 12, dark loam soil and subsoil from near Pales- 
