The Edwards Plateau is a geographic region at the crossroads of

Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known a ...

South South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...

, and

West Texas West Texas is a loosely defined region in the U.S. state of Texas, generally encompassing the arid and semiarid lands west of a line drawn between the cities of Wichita Falls, Abilene, and Del Rio. No consensus exists on the boundary betwe ...

. It is bounded by the

Balcones Fault The Balcones Fault or Balcones Fault Zone is an area of largely normal faulting Edwards Aquifer in the U.S. state of Texas that runs roughly from the southwest part of the state near Del Rio to the north-central region near Dallas along ...

to the south and east, the Llano Uplift and the

Llano Estacado The Llano Estacado (), sometimes translated into English as the Staked Plains, is a region in the Southwestern United States that encompasses parts of eastern New Mexico and northwestern Texas. One of the largest mesas or tablelands on the North A ...

to the north, and the

Pecos River The Pecos River ( es, Río Pecos) originates in north-central New Mexico and flows into Texas, emptying into the Rio Grande. Its headwaters are on the eastern slope of the Sangre de Cristo mountain range in Mora County north of Pecos, New Mexico ...

and

Chihuahuan Desert The Chihuahuan Desert ( es, Desierto de Chihuahua, ) is a desert ecoregion designation covering parts of northern Mexico and the southwestern United States. It occupies much of far West Texas, the middle to lower Rio Grande Valley and the lowe ...

to the west.

San Angelo San Angelo ( ) is a city in and the county seat of Tom Green County, Texas, United States. Its location is in the Concho Valley, a region of West Texas between the Permian Basin to the northwest, Chihuahuan Desert to the southwest, Osage Plai ...

, Austin,

San Antonio ("Cradle of Freedom") , image_map = , mapsize = 220px , map_caption = Interactive map of San Antonio , subdivision_type = Country , subdivision_name = United States , subdivision_type1= State , subdivision_name1 = Texas , subdivision_t ...

, and Del Rio roughly outline the area. The southeast portion of the plateau is known as the

Texas Hill Country The Texas Hill Country is a geographic region of Central and South Texas, forming the southeast part of the Edwards Plateau. Given its location, climate, terrain, and vegetation, the Hill Country can be considered the border between the Amer ...

Natural history

The bedrock consists primarily of

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...

, with elevations ranging between 100 and 3000 ft. Caves are numerous. The landscape of the plateau is mostly

savanna A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...

scattered with trees. It mostly lacks deep soil suitable for farming, though the soil type is fertile

mollisol Mollisol is a soil type which has deep, high organic matter, nutrient-enriched surface soil ( a horizon), typically between 60 and 80 cm in depth. This fertile surface horizon, called a mollic epipedon, is the defining diagnostic feature of ...

, so some

cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor p ...

, grain

sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family ( Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many ot ...

, and oats are grown. For the most part, though, the thin soil and rough terrain areas are primarily

grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...

regions, with cattle, sheep, and goats ( Angora and meat types) predominant. Several rivers cross the region, which generally flow to the south and east through the Texas Hill Country toward the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United S ...

; springs occur (in wet years), but permanent surface water supplies are sparse throughout the area, except for man-made reservoirs. The area is well drained; rainwater flows into the

Edwards Aquifer The Edwards Aquifer is one of the most prolific artesian aquifers in the world. Located on the eastern edge of the Edwards Plateau in the U.S. state of Texas, it is the source of drinking water for two million people, and is the primary water su ...

recharge zone at the south of the plateau to feed rivers to the south. Rainfall varies from 15 to 33 inches per year, typically, from northwest to southeast, and the area has a moderate temperature and a reasonably long growing season.

Flora

Trees of the savanna include

juniper Junipers are coniferous trees and shrubs in the genus ''Juniperus'' () of the cypress family Cupressaceae. Depending on the taxonomy, between 50 and 67 species of junipers are widely distributed throughout the Northern Hemisphere, from the Arcti ...

s (locally called mountain cedar),

oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...

species scattered over grasses, a vegetation type historically shaped by droughts and regular fires. Some

pecan The pecan (''Carya illinoinensis'') is a species of hickory native to the southern United States and northern Mexico in the region of the Mississippi River. The tree is cultivated for its seed in the southern United States, primarily in Georgia, ...

trees are found near the springs and rivers, which are typically lined with stands of

bald cypress ''Taxodium distichum'' (bald cypress, swamp cypress; french: cyprès chauve; ''cipre'' in Louisiana) is a deciduous conifer in the family Cupressaceae. It is native to the southeastern United States. Hardy and tough, this tree adapts to a wide r ...

. The Balcones Fault is associated with the Edwards Plateau formation. This fault line is an ecological demarcation for the range definition of a number of species.

Fauna

Caves of the Edwards Plateau are important habitats for a great deal of wildlife. The area is home to some of the largest colonies of bats in the world, including millions of

Mexican free-tailed bat The Mexican free-tailed bat or Brazilian free-tailed bat (''Tadarida brasiliensis'') is a medium-sized bat native to the Americas, so named because its tail can be almost half its total length and is not attached to its uropatagium. It has be ...

s. The largest colony of these inhabits Bracken Cave near San Antonio, while the

Congress Avenue Bridge The Ann W. Richards Congress Avenue Bridge (formerly known simply as the Congress Avenue Bridge) crosses over Lady Bird Lake in Austin, Texas. Before construction of the Longhorn Dam was completed in 1960, the bridge crossed the Colorado R ...

in Austin is the summer home for over half a million (they winter in Mexico) and is the largest bat colony anywhere in an urban area. The Edwards Plateau is home to at least 14 endemic freshwater fishes, including two subterranean species of catfish and 13 fish species considered to be spring-associated. Mechanisms for spring association of fishes is not fully understood, but thought to mediated by water temperature. The large numbers of reptiles and birds also include breeding populations of the Texan endemic

golden-cheeked warbler The golden-cheeked warbler (''Setophaga chrysoparia'') is an endangered species of bird that breeds in Central Texas, from Palo Pinto County southwestward along the eastern and southern edge of the Edwards Plateau to Kinney County. The golden-ch ...

(''Setophaga'' ''chrysoparia''). Nearly all the natural habitat of the plateau has been converted to ranchland, farmland, or urban areas, such as Austin and San Antonio, with only about 2% remaining in scattered fragments, especially to the east of the plateau. Further alteration to the savanna has incurred though the encroachment of shrubs now that grassland fires are carefully controlled. Small areas of intact habitat remain, particularly around Austin, where areas are protected, such as the

Balcones Canyonlands National Wildlife Refuge Balcones Canyonlands is a national wildlife refuge located in the Texas Hill Country to the northwest of Lago Vista, Texas. The refuge was formed in 1992 to conserve habitat for two endangered songbirds, the golden-cheeked warbler and the b ...

. Another important area for wildlife is

Fort Hood Fort Hood is a United States Army post located near Killeen, Texas. Named after Confederate General John Bell Hood, it is located halfway between Austin and Waco, about from each, within the U.S. state of Texas. The post is the headquar ...

military base.

Human history

Earliest human settlement of this area was by Native Americans. First it was used and wandered about by

Jumano Jumanos were a tribe or several tribes, who inhabited a large area of western Texas, New Mexico, and northern Mexico, especially near the Junta de los Rios region with its large settled Indigenous population. They lived in the Big Bend area in ...

and

Coahuiltecan The Coahuiltecan were various small, autonomous bands of Native Americans who inhabited the Rio Grande valley in what is now southern Texas and northeastern Mexico. The various Coahuiltecan groups were hunter-gatherers. First encountered by Europ ...

groups, then the Apacheria extended into the Southern Plains by the forerunners of the Lipan and

Mescalero Mescalero or Mescalero Apache ( apm, Naa'dahéńdé) is an Apache tribe of Southern Athabaskan–speaking Native Americans. The tribe is federally recognized as the Mescalero Apache Tribe of the Mescalero Apache Reservation, located in south- ...

Apaches. After the expulsion of the Apachean groups from the Plains by the Comanche, this area was dominated by the

Penateka The Comanche or Nʉmʉnʉʉ ( com, Nʉmʉnʉʉ, "the people") are a Native American tribe from the Southern Plains of the present-day United States. Comanche people today belong to the federally recognized Comanche Nation, headquartered in ...

band of the Southern Comanche.

Counties in the Edwards Plateau

According to the

Texas Parks and Wildlife Department The Texas Parks & Wildlife Department (TPWD) is a Texas state agency that oversees and protects wildlife and their habitats. In addition, the agency is responsible for managing the state's parks and historical areas. Its mission is to manage ...

, all or portions of these 41 counties comprise the Edwards Plateau geographic region:Texas Parks and Wildlife http://www.tpwd.state.tx.us/huntwild/wild/birding/pif/assist/pif_regions/region_7.phtml The Texas Water Development Board, a state government agency, includes additional counties all or partly in the Edwards Plateau area: A map showing the counties is provided by

for the Edwards Plateau Ecoregion. The ecoregion is somewhat larger than the geographic region, as the map from Texas Parks And Wildlife includes additional counties that are listed by the Texas Water Development Board, notably the isolated area of Edwards Plateau in Taylor, Runnels, and Nolan Counties that is separated from the main region.

Edwards Plateau gallery

File:San Saba River near Sloan, San Saba County, Texas, USA (9 May 2014).jpg,

San Saba River The San Saba River is a river in the U.S. state of Texas. It is an undeveloped and scenic waterway located on the northern boundary of the Edwards Plateau. Course The river begins in two primary branches. The North Valley Prong runs east throu ...

near Sloan, San Saba County (9 May 2014) File:Wildflowers on ranchland, State Highway 965, Llano County, Texas, USA (13 April 2012).jpg, Wildflowers on ranchland, State Highway 965, Llano County (13 April 2012) File:Llano River seen from County Road 320, Kimble County, Texas, USA (17 April 2015).jpg,

Llano River The Llano River ( ) is a tributary of the Colorado River, about long, in Texas in the United States. It drains part of the Edwards Plateau in Texas Hill Country northwest of Austin. Two spring-fed tributaries, the North and South Llano, stret ...

from County Road 320, Kimble County (17 April 2015) File:Texas cooter (Pseudemys texana) and red-eared slider (Trachemys scripta), Colorado River, Travis County, Texas, USA (12 April 2012).jpg, Texas cooter ('' Pseudemys texana'') and red-eared slider ('' Trachemys scripta''), Colorado River, Travis County (12 April 2012) File:The Guadalupe River in Kerr County, Texas, USA (8 May 2014).jpg, The Guadalupe River in Kerr County (8 May 2014) File:Ranchland with Texas bluebonnets (Lupinus texensis) in western Kerr County, Texas, USA (17 April 2015).jpg, Ranchland with Texas bluebonnets ('' Lupinus texensis'') in western Kerr County (17 April 2015) File:Bald Cypress (Taxodium distichum) growing on the Guadalupe River, Kerr County, Texas, USA (14 April 2012).jpg, Bald cypress (''

Taxodium distichum ''Taxodium distichum'' (bald cypress, swamp cypress; french: cyprès chauve; ''cipre'' in Louisiana) is a deciduous conifer in the family Cupressaceae. It is native to the southeastern United States. Hardy and tough, this tree adapts to a wide r ...

'') growing on the Guadalupe River, Kerr County (14 April 2012) File:Ranchland in the Edwards Plateau, Mason County, Texas, USA (17 April 2015).jpg, Ranchland in the Edwards Plateau, Mason County (17 April 2015) File:Crevice spiny lizard (Sceloporus poinsettii), Mason County, Texas, USA (9 May 2014).jpg, Crevice spiny lizard ('' Sceloporus poinsettii''), Mason County, Texas, USA (9 May 2014) File:Highway 187 in the Edwards Plateau, Bandera County, Texas, USA (14 April 2012).jpg, Highway 187 in the Edwards Plateau, Bandera County, Texas, USA (14 April 2012) File:Limestone bluff, typical of the Edwards Plateau, Highway 336, Real County, Texas, USA (14 Apr 2012).jpg, Limestone bluff, typical of the Edwards Plateau, Highway 336, Real County (14 Apr 2012) File:Ranchland seen from Highway 336, Real County, Texas, USA (14 April 2012).jpg, Ranchland seen from Highway 336, Real County (14 April 2012) File:Scarlet Penstemon (Penstemon triflorus), endemic to Edwards Plateau, Edwards County, Texas, USA (18 April 2015).jpg, Scarlet penstemon ('' Penstemon triflorus''), endemic to the Edwards Plateau, Edwards County (18 April 2015) File:Ranch road in southern Edwards County, Texas, USA (18 April 2015).jpg, Ranch road in southern Edwards County (18 April 2015). File:Cedar Creek, Edwards County, Texas, USA (18 April 2015).jpg, Cedar Creek, Edwards County (18 April 2015)

References

External links

* *
Texas counties map showing the ecoregion
{{Coord, 30.3, -99.6, display=title Landforms of Texas Plateaus of the United States Regions of Texas Tropical and subtropical grasslands, savannas, and shrublands of the United States Ecoregions of the United States Geography of Texas Grasslands of Texas Texas Hill Country Physiographic sections