flow directly to the Gulf of Mexico, and all, except the Brazos and Rio Grande, empty through estuaries into the coast lagoons. The principal rivers are the Sabine, on the Louisiana boundary, the Neches, Trinity, Brazos, Colorado, Guadalupe, San Antonio, Nueces, and the Rio Grande. Most of these rivers flow through deep cañons immediately after leaving the Great Plains. Several of them are navigable for considerable distances at high water, but their mouths are generally obstructed by bars.
Climate. As Texas reaches to within two and a half degrees of the tropical zone, it naturally has a warm climate, but the great range in latitude, and to some extent in altitude, produces also a considerable range in climatic conditions. Although warm, the climate is drier and less enervating than that of the other Gulf States. The mean temperature in July at Galveston on the coast is 83.7°, at El Paso in the extreme west 81.9°, and at Amarillo in the northwest 76°. The corresponding figures for January are 52.7° at Galveston, 44.5° at El Paso, and 31.9° at Amarillo. On the coast the temperature seldom falls below the freezing point, while in the northwest it may fall several degrees below zero. In the western uplands, on the other hand, the temperature rises above 100°, while on the coast the maximum is between 90° and 95°. In winter the State is subject to severe north winds, known as northers, which often lower the temperature 50° in a few hours. In the eastern section the southeast winds from the Gulf are prevalent and bring abundant rain to that part of the State. The rainfall decreases rapidly westward, so that in the western part it is insufficient for agriculture. In the eastern portion near the mouth of the Sabine River the rainfall is sometimes over 60 inches, while in the extreme south, even near the coast, it is sometimes only five inches in a year. The normal annual average at Galveston is 49 inches, at Corpus Christi 30, at Austin 34, at Abilene, nearly in the centre of the State, 25, at Amarillo in the Panhandle 22, and at El Paso 9 inches.
Soil. The alluvial bottom lands around the lower river courses are the most fertile portions of the State. Next to these ranks the Black Prairie belt, which is covered with a remarkably fertile marl formed by the mixture of clay with the disintegrated Cretaceous limestone. The soil of the coastal plain is generally sandy; in some places the sand is mixed with clay to form a black loam. In the northwest there are heavy deposits of red clay containing much potash, but little nitrogenous matter. The soil on the southern plateau is thin, but the Llano Estacado is covered with a red sandy loam which would be rendered fertile by irrigation.
Flora. The principal forest area of Texas is in the extreme eastern portion. In the sandy coastal plain the pine is the prevailing tree, long-leaf pine in the lower and short-leaf pine in the higher pine barrens. Westward toward the centre of the State the deciduous species predominate, including oaks, elm, maple, hickory, sycamore, mulberry, sweet gum, ash, and walnut. The Osage orange is also common here, and the palmetto in the eastern part lends a tropical aspect to the vegetation. In the river-bottoms the characteristic species are cottonwood, pecan, live oak, and cypress. Along the western border of the Black Prairie two parallel belts of hardwood forest, chiefly oak, and known as the Cross Timbers, extend southward as far as the Brazos River. To the south and west of these the State is practically treeless except along the river courses. There are also scattered areas of scrub and chaparral composed largely of mesquite, the most characteristic tree of western Texas. Still farther west even the prairie grasses give place to or grow in the midst of a desert flora in which the yuccas and cacti are predominant.
For Fauna, see United States; also Rocky Mountains.
Geology and Minerals. The oldest rocks of the State come to the surface in the Central Denuded Region. In the southern part of this region, west of Austin, there is a small area of Archæan rock surrounded by a narrow outcrop of Cambrian and Silurian strata. To the north of this there is a considerable area of Carboniferous formation followed on the northwest along the eastern base of the Llano Estacado by a still larger region referred by some to the Permian, by others to the Jurassic system. Another large area of Paleozoic and early Mesozoic rocks is found in the Trans-Pecos region, where the predominant formation is the Jura-Trias, with small scattered outcrops of Carboniferous and other Paleozoic, together with some recent igneous rocks. The Llano Estacado, like the Great Plains to the north, is of very recent formation, consisting of lacustrine Tertiary deposits. The southern plateau or Grand Prairie region is older, being of Lower Cretaceous formation, and this formation also skirts the central Paleozoic area on the east. It is succeeded on the east by a band of Upper Cretaceous strata constituting the Black Prairie belt. Beyond this the entire coastal plain is composed of marine Tertiary deposits. Workable beds of bituminous coal occur in the central portion of the State, and large deposits of lignite are stretched along the western border of the coastal plain. In the eastern part of the State, near the mouth of the Sabine, petroleum deposits of great extent have been found at a depth of about 1000 feet. Iron and copper ores, as well as lead and tin, occur in the southeastern part of the central region, and silver is found in the west. The Trans-Pecos region, still but partly explored, probably contains varied mineral deposits, the most important being the cinnabar ores found in the Cretaceous limestone in the south. The most important of the remaining minerals in the State are the immense beds of gypsum found in the Permian strata of the northwestern Red Lands.
Mining. Mining, which had until recently been of little importance, bids fair to acquire large proportions. The value of coal increased almost steadily from $412,300 in 1891 to $1,907,024 in 1901. In the latter year there were mined 787,700 short tons of bituminous coal and 296,681 short tons of lignite. The production of petroleum practically began in 1897. The yield has increased very rapidly, amounting to 4,393,658 barrels in 1901. The silver exploited in the same year was valued at $283,440. Brick and tile made from local clays in that year amounted to $1,632,189. Gypsum is mined in the northwestern part. Cinnabar and salt are mined and some granite, sandstone, and limestone are quarried. There are a number of valuable mineral springs.
