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ECONOMIC GEOLOGY.
SOILS.
The soils of Grimes county, with the exception of the soils of the bottom lands, may be characterized as nearly all fit for cultivation, although generally poor. Some portions of the prairies, though usually covered with a thin or scanty vegetation, do not have a sufficient depth of soil for farming purposes, and at other places the gray sandstone formations have no soil at all. The areas, however, in which the rock is exposed are of only a limited extent. Those in which the soil is thin are greater, but still form a very small portion of the county and are generally occupied as pasture land. The soils belong chiefly to the two grades-alluvial, or sedimentary, and residual, or sedentary. The alluvial, or sedimentary, are those which have been deposited in and from flowing water, and include all bottom and second bottom valley soils. The residual soils are those which result from the quiet action of the changes of temperature, etc., and are due to the disintegration of the underlying deposits, and consequently have not been removed from their original site, and partake largely of the nature and constitution of the underlying beds.
ALLUVIAL SOIL.
These soils occur only in the valleys of the Brazos and Navasota rivers, and form a belt of low, flat country, from one to three miles in width, extending through the entire length of that portion of the country adjacent to these rivers. Some of the larger streams, such as Beason's, Holland, and Gibbon's creeks, have wide deltas or bottoms at their mouths, often extending for several miles interiorly along their course. These soils cover nearly one-fifth of the county.
Much of this area is subject to periodic overflows from the two rivers, and a very small part of it is under cultivation. The greater portion is covered with a heavy growth of timber.
These alluvial soils are mostly a stiff clay, laminated in places, and portions of them have a considerable admixture of sand. They are dark brown in color, and from two to six feet or more in depth. Where in cultivation they are the most productive soils in the county. The chief productions are cotton and corn.
Analyses show them to be rich in lime, phosphoric acid, and organic matter, and although the proportions of potash are slightly below the normal, may be considered as of more than average fertility.
Analysis of soil and subsoil of Brazos river bottom, Grimes county:
"Analysis by P. S. Tilson.