Here the chief wealth is in the minerals, consisting of silver, copper, and lead of good grade and some gold, tin, zinc, and quicksilver.
Local conditions have, however, retarded the mining development, and silver and quicksilver are the only ores worked on a commercial basis.
On the Stockton Plateau the formation resembles that of Edward's, but the rainfall being less, averaging only fifteen inches annually, it is used almost entirely for cattle.
On the Edward's Plateau the upland prairies are mainly given over to cattle, sheep, and goats; in the cañon valleys, however, are alluvial plains in which cotton, corn, milo-maize, wheat, and oats are a success.Wherever the climate becomes arid cattle raising increases as an industry.The Central Basin is the second great natural province.Formerly this region was devoted entirely to cattle, but now alfalfa, barley, broom-corn, maize, cotton, wheat, and fruits are being successfully cultivated.The water supply may be made abundant mainly from wells at a depth of 100 to 600 feet.This region, situated in northwest and central-west Texas, was once covered with cretaceous materials, but now is denuded by the head waters of the Red, Brazos, and Colorado Rivers.Its southern extremity, the "Llano Country", as it is called, has a granite foundation, much quarried, and deposits of hematite and magnetite occur here plentifully.Deposits of salt, clay, and gypsum occur in this area.The third natural province of Texas is the Plateau Province, having three great divisions: the Llano Estacado, Staked or Palisaded Plains, which extend beyond the limits of the state, and the Edward's and Stockton Plateau. The first of these, nearest the coast, is called the Coastal Plain, consisting of Coast Prairies, a Tertiary area, and Black Prairies. Four great natural provinces, running in general direction from south to north, are formed by geological development.