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Geography of Texas

2007 Schools Wikipedia Selection. Related subjects: North American Geography

   The geography of Texas covers a wide and far reaching scope. Occupying
   about 7% of the total water and land area of the U.S., it is the second
   largest state after Alaska, and is the southernmost part of the Great
   Plains, which ends in the south against the folded Sierra Madre
   Oriental of Mexico. Texas is in the south-central part of the United
   States of America, and is considered to form part of the U.S. South and
   also part of the U.S. Southwest.

   The Rio Grande, Red River and Sabine River all provide natural state
   lines where Texas borders Oklahoma on the north, Louisiana and Arkansas
   on the east, and New Mexico and the Mexican states of Chihuahua,
   Coahuila, Nuevo León, and Tamaulipas to the south. Austin, the state
   capital, is farther south than all other US state capitals except
   Honolulu.

   By residents, the state is generally divided into North Texas, East
   Texas, Central Texas, South Texas, and West Texas, but according to the
   Texas Almanac, Texas has four major physical regions: Gulf Coastal
   Plains, Interior Lowlands, Great Plains, and Basin and Range Province.
   This has been cited as the difference between human geography and
   physical geography, although the fact that Texas was granted (and
   retains to this day) the prerogative to divide into as many as five
   U.S. states may be a historical motive for Texans defining their state
   as containing exactly five regions.

   Some regions of Texas are associated with the South more than the
   Southwest (primarily East Texas), while other regions share more
   similarities with the Southwest than the South (primarily West Texas
   and South Texas). Even the northwestern part of the state seems to have
   more in common with parts of the United States (Kansas and Nebraska)
   that are considered " midwestern" and never "southern". The size of
   Texas prohibits easy categorization of the entire state wholly in any
   recognized region of the United States; geographic, economic, and even
   cultural diversity between regions of the state preclude treating Texas
   as a region in its own right.

Climate

   Texas rivers map showing Captain Marcy's route though Texas in 1854.
   Enlarge
   Texas rivers map showing Captain Marcy's route though Texas in 1854.

   Continental, Mountain, and Modified Marine are the three major climatic
   types of Texas, with no distinguishable boundaries. Modified Marine, or
   subtropical, dominates the majority of the state. Texas has an annual
   precipitation range from 60.57 inches in Jasper County, East Texas, to
   9.43 inches in El Paso. The record high of 120 °F was reached at
   Seymour on Aug. 12, 1936, and Monahans on June 28, 1994. The low also
   ties at -23 °F in Tulia on Feb. 12, 1899, and Seminole on Feb. 8, 1933.

   Most of Texas is under direct threat from drought, heat, hail, high
   winds, flash floods, hurricanes, and tornados. Select areas
   occasionally suffer from dust storms, river floods, snow and ice.
   Amarillo has the highest average wind speed in Texas at 14.3 mph.

Physical geography

   With 10 climatic regions, 14 soil regions, and 11 distinct ecological
   regions, classifing regions becomes problematic with differences in
   soils, topography, geology, rainfall, and plant and animal communities.
   The geographic centre of Texas is about 15 miles northeast of Brady in
   northern McCulloch County. Guadalupe Peak, at 8,749 feet above sea
   level is the highest point in Texas. The lowest being sea level where
   Texas meets the Gulf of Mexico. Texas has five state forests and 120
   state parks for a total over 605,000 acres (2450 km²). There are 3,700
   named streams and 15 major river systems flowing through 191,000 miles
   of Texas. Eventually emptying into seven major estuaries, these rivers
   support over 212 reservoirs.

   Texas is so large in its east-west expanse that El Paso, in the western
   corner of the state, is closer to San Diego, California than to
   Beaumont, near the Louisiana state line; Beaumont, in turn, is closer
   to Jacksonville, Florida than it is to El Paso. Also, Texarkana, in the
   northeastern corner of the state, is about the same distance from
   Chicago, Illinois as it is to El Paso. The north-south expanse is
   similarly impressive; Dalhart, in the northwestern corner of the state,
   is closer to the state capitals of Kansas, Colorado, New Mexico,
   Oklahoma and Wyoming than it is to Austin, its own state capital.

Gulf Coastal Plains

   Caddo Lake
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   Caddo Lake

   The Gulf Coastal Plains from the Gulf of Mexico inland to the Balcones
   Fault and the Eastern Cross Timbers. This large area stretches from the
   cities of Paris to San Antonio to Del Rio but shows a large variety in
   vegetation. The thick pineywoods of east Texas and the brush country
   south of San Antonio are found here. With 20 - 50 inches annual
   rainfall, this is a nearly level, drained plain dissected by streams
   and rivers flowing into estuaries and marshes. Windblown sands and
   dunes, grasslands, oak mottes and salt marshes make up the seaward
   areas. National Parks include Big Thicket National Preserve, Padre
   Island National Seashore and the Palo Alto Battlefield National
   Historic Site.

Interior Lowlands

   Looking north at the Caprock Escarpment.
   Enlarge
   Looking north at the Caprock Escarpment.

   The Interior Lowlands are bounded by the Caprock Escarpment to the
   west, the Edwards Plateau to the south, and the Eastern Cross Timbers
   to the east. This area includes the North Central Plains around the
   cities of Abilene and Wichita Falls, the Western Cross Timbers to the
   west of Fort Worth, the Grand Prairie, and the Eastern Cross Timbers to
   the east of Dallas. With 35 - 50 inches annual rainfall, gently rolling
   to hilly forested land is part of a larger pine-hardwood forest of
   oaks, hickories, elm and gum trees. Soils vary from coarse sands to
   tight clays or red-bed clays and shales. The only National Park in this
   region is Lake Meredith National Recreation Area.

Great Plains

   Hill Country
   Enlarge
   Hill Country

   The Great Plains include the Llano Estacado, the Panhandle, Edwards
   Plateau, Toyah Basin, and the Llano Uplift. It is bordered on the east
   by the Caprock Escarpment in the panhandle and by the Balcones Fault to
   the southeast. Cities in this region include Austin, San Angelo,
   Midland and Odessa, Lubbock, and Amarillo. The Hill Country is a
   popular name for the area of hills along the Balcones Escarpment and is
   a transitional area between the Great Plains and the Gulf Coastal
   Plains. With 15 - 31 inches annual rainfall, the southern end of the
   Great Plains are gently rolling plains of shrub and grassland, and home
   to the dramatic Caprock Canyons and Palo Duro Canyon state parks. The
   largest concentration of playa lakes in the world (nearly 22,000) is on
   the Southern High Plains of Texas and Eastern New Mexico.

   Texas' Blackland Prairie were some of the first areas farmed in Texas.
   Highly expansive clays with characteristic dark coloration, called the
   Houston Black series, occur on about 1.5 million acres (6000 km²)
   extending from north of Dallas south to San Antonio. The Professional
   Soil Scientists Association of Texas has recommended to the State
   Legislature that the Houston Black series be designated the State soil.
   The series was established in 1902. National Parks in this area are the
   Lyndon B. Johnson National Historical Park and the San Antonio Missions
   National Historical Park.

Basin and Range Province

   El Capitan
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   El Capitan
   Rio Grande Valley
   Enlarge
   Rio Grande Valley

   Trans-Pecos Natural Region with less than 12 inches annual rainfall.
   The most complex Natural Region, it includes Sand Hills, the Stockton
   Plateau, desert valleys, wooded mountain slopes and desert grasslands.
   The Basin and Range Province in extreme western Texas, west of the
   Pecos River beginning with the Davis Mountains on the east and the Rio
   Grande to its west and south. The Trans-Pecos region is the only part
   of Texas regarded as mountainous and includes seven named peaks in
   elevation greater than 8,000 feet (2,400 m). With less than 12 inches
   annual rainfall, this region includes sand hills, desert valleys,
   wooded mountain slopes and desert grasslands. The vegetation diversity
   includes at least 268 grass species and 447 species of woody plants.
   National Parks include the Amistad National Recreation Area, Big Bend
   National Park, Chamizal National Memorial, Fort Davis National Historic
   Site, Guadalupe Mountains National Park, and the Rio Grande Wild and
   Scenic River.

Geology

   SeaWIFS satellite image looking east over the southern United States,
   showing the location of Dallas and Fort Worth
   Enlarge
   SeaWIFS satellite image looking east over the southern United States,
   showing the location of Dallas and Fort Worth

   Texas is mostly sedimentary rocks, with east Texas underlain by a
   Cretaceous and younger sequence of sediments, the trace of ancient
   shorelines east and south until the active continental margin of the
   Gulf of Mexico is met. This sequence is built atop the subsided crest
   of the Appalachian Mountains– Ouachita Mountains–Marathon Mountains
   zone of Pennsylvanian continental collision, which collapsed when
   rifting in Jurassic time opened the Gulf of Mexico. West from this
   orogenic crest, which is buried beneath the Dallas– Waco– Austin– San
   Antonio trend, the sediments are Permian and Triassic in age. Oil is
   found in the Cretaceous sediments in the east, the Permian sediments in
   the west, and along the Gulf coast and out on the Texas continental
   shelf. A few exposures of Precambrian igneous and metamorphic rocks are
   found in the central and western parts of the state, and Oligocene
   volcanic rocks are found in far west Texas, in the Big Bend area. A
   blanket of Miocene sediments known as the Ogallala formation in the
   western high plains region is an important aquifer. Texas has no active
   or dormant volcanoes and few earthquakes, being situated far from an
   active plate tectonic boundary. (The Big Bend area is the most
   seismically active; however, the area is sparsely populated and suffers
   minimal damages and injuries, and no known fatalities have been
   attributed to a Texas earthquake.)

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