The eastern and northern part, where the rainfall reaches from forty to fifty inches annually, are suitable for rice culture, which is localized there; in the central portion along the coast where the rainfall is less, sugar-cane, fruit, and "truck" are extensively cultivated, while in the southwest, with a rainfall of only 20 to 28 inches annually, cotton culture and "cattle raising on the range" are the chief industries. Different climatic conditions with respect to rainfall vary the products of different parts of this region.This Tertiary area also is divided by climatic conditions.
The fourth province is that of the Trans-Pecos Mountains, with elevations ranging from 5000 to 9500 feet.
Here the chief wealth is in the minerals, consisting of silver, copper, and lead of good grade and some gold, tin, zinc, and quicksilver.
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 Llano Estacado, a plateau 2500 to 4000 feet in elevation, derives its name from being itself an extensive uplifted mesa, surrounded, except on the Edward's Plateau side, by "breaks", cliffs, or walls, which, as palisades, have to be climbed before the plateau is attained.
In the east there are numerous small streams flowing south and east into the Gulf of Mexico, in the Trans-Pecos region there are practically no streams at all that reach the sea.
In the arid regions the drainage channels flow only for a short time after rainfall.
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.
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.
It has a broad plain where it enters the state, but descends into an inaccessible cañon as it approaches the Rio Grande.
The Canadian River crosses the extreme north of the state from west to east merely as a small stream on a wide bed of wet sand.
The plateaux are treeless, grass-covered prairies; the soils are fine, sandy loams, and the annual rainfall only from fifteen to twenty inches.