The Balcones Fault Zone is a tensional structural system in Texas Houston is the largest city in Texas and the fourth-largest in the United States, while San Antonio is the second largest in the state and seventh largest in the United States. Dallas–Fort Worth and Greater Houston are the fourth and sixth largest United States metropolitan areas, respectively. Other major cities include El Paso and Austin—the (USA ^ b. English is the de facto language of American government and the sole language spoken at home by 80% of Americans age five and older. Spanish is the second most commonly spoken language) that runs approximately from the southwest part of the state near Del Rio, Texas Del Rio is a border city in and the county seat of Val Verde County, Texas, United States.. Del Rio is connected with Ciudad Acuña via the Lake Amistad Dam International Crossing and Del Río-Ciudad Acuña International Bridge. Del Rio is also home to Laughlin Air Force Base, the busiest pilot training base in the United States Air Force. Del Rio' to the north central region near Waco, Texas Waco is a city in and the county seat of McLennan County, Texas. The city has a 2007 estimated total population of 120,465. The Waco Metropolitan Statistical Area consists of McLennan County and as of 2007, has an estimated population of 224,668 along Interstate 35 Interstate 35 is a north–south Interstate Highway in the central United States. I-35 stretches from Laredo, Texas, on the U.S.-Mexico border to Duluth, Minnesota, at Minnesota Highway 61 (London Road) and 26th Avenue East. Many interstates used to have splits or spurs indicated with suffixed letters (N/S/E/W), but I-35 is the only one that still. The Balcones Fault zone is made up of many smaller features, including normal faults In geology, a fault is a planar fracture in rock in which the rock on one side of the fracture has moved with respect to the rock on the other side. Large faults within the Earth's crust result from differential or shear motion, and active fault zones are the causal locations of most earthquakes. Energy release during rapid slippage along faults, grabens In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural, and horsts In physical geography and geology, a horst is the raised fault block bounded by normal faults or graben. A horst is formed from extension of the Earth's crust. The raised block is a portion of the crust that generally remains stationary or is uplifted while the land has dropped on either side.[1] One of the most obvious features is the Mount Bonnell Mount Bonnell , also known as Covert Park, is a prominent point alongside Lake Austin in Austin, Texas. It has been a popular tourist destination since the 1850s. The mount provides a vista for viewing the city of Austin, Lake Austin, and the surrounding hills Fault.[2]
The location of the fault zone may be related to the Ouachita Mountains The Ouachita Mountains are a mountain range located in west central Arkansas, southeastern Oklahoma and north-east Texas. The range's subterranean roots may extend as far as central Texas, or beyond it to the current location of the Marathon Uplift. Along with the Ozark Mountains, the Ouachita Mountains form the US Interior Highlands, the only, formed 300 million years ago during a continental collision. Although long-since eroded away in Texas, the roots of these ancient mountains still exist, buried beneath thousands of feet of sediment Sediment is naturally-occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself. These buried Ouachita Mountains may still be an area of weakness that becomes a preferred site for faulting when stress exists in the Earth's crust In geology, a crust is the outermost solid shell of a rocky planet or moon, which is chemically distinct from the underlying mantle. The crusts of Earth, our Moon, Mercury, Venus, Mars, Io, and other planetary bodies have been generated largely by igneous processes, and these crusts are richer in incompatible elements than their respective mantles. The Balcones Fault zone was most recently active about 15 million years ago during the Miocene The Miocene is a geological epoch of the Neogene Period and extends from about 23.03 to 5.33 million years before the present . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words μείων (meiōn, “less”) and καινός (kainos, “new”) and means "less recent" because it has 18% fewer modern sea epoch. This activity was related to subsidence Subsidence is the motion of a surface as it shifts downward relative to a datum such as sea-level. The opposite of subsidence is uplift, which results in an increase in elevation. Ground subsidence is of concern to geologists, structural engineers and surveyors of the Texas Coastal Plain The Texas Coastal Bend refers to the flat area of land along the Texas coast. It is home to many cities including Brownsville, Corpus Christi, Kingsville, Port Lavaca, Galveston, Victoria, Beaumont, and Houston. The Coastal Bend includes the barrier islands of Texas and the Laguna Madre. According to the United States 2000 Census the Texas Coastal, most likely from the large amount of sediment deposited on it by Texas rivers. The Balcones Fault zone is not active today, and is in one of the lowest risk zones for earthquakes An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are measured with a seismometer; a device which also records is known as a seismograph. The moment magnitude (or the related and mostly obsolete Richter magnitude) of an earthquake is conventionally reported, with magnitude 3 or in the United States.[3]
The surface expression of the fault is the Balcones Escarpment Usually escarpment is used interchangeably with scarp . But some sources differentiate the two terms, where escarpment refers to the margin between two landforms, while scarp is synonymous with a cliff or steep slope. The surface of the steep slope is called a scarp face. Scarps are generally formed by one of two processes: either by differential, which forms the eastern boundary of the Texas Hill Country The Texas Hill Country is a vernacular term applied to a region of Central Texas, that features tall rugged hills that consist of thin layers of soil lying ontop of either limestone or granite. It also includes the Llano Uplift and the second largest granite monadnock in the United States, Enchanted Rock, which is located 18 miles north of and the western boundary of the Texas Coastal Plain and consists of cliffs and cliff-like structures. Subterranean features such as Wonder Cave Wonder Cave is a show cave located in the Balcones Fault in San Marcos, Texas . Its entrance is one mile southwest of the county courthouse in San Marcos. The cave is reported to be the only commercially operated dry-formed cave in the United States ("dry-formed" because the fissure was opened not by erosion but by the earthquake that and numerous other smaller caves are found along the fault zone.
Many cities are located along this fault zone, and that is not a coincidence. Springs such as San Pedro Springs San Pedro Springs is the name of a cluster of springs in Bexar County, Texas, U.S.A. These springs provide water for San Pedro Creek, which flows into the San Antonio River, Comal Springs Comal Springs are the largest concentration of naturally occurring freshwater springs in Texas. They are located in the city of New Braunfels and are the result of water percolating through the Edwards Aquifer formation, San Marcos Springs San Marcos Springs is the second largest natural cluster of springs in Texas. The springs are located in the city of San Marcos, Texas, about 30 miles southwest of Austin and 46 miles (74 km) northeast of San Antonio, Barton Springs Barton Springs is a set of four natural water springs located on the grounds of Zilker Park in Austin, Texas resulting from water flowing through the Edwards Aquifer. The largest spring, Main Barton Spring supplies water to Barton Springs Pool, a popular recreational destination in Austin. The smaller springs are located nearby, two with man-made and Salado Springs Salado Springs is the name of five groups of springs at the town of Salado in Bell County, Texas, in the United States. The springs are located 48 miles north of Austin or 135 miles (217 km) south of Dallas are found in the fault zone and provide a source of fresh water and an obvious place for human settlement.
The Balcones Fault Zone is a demarcation line for certain ecological systems and species distributions. For example, the California Fan Palm (Washingtonia filifera Washingtonia filifera , common names Desert Fan Palm, American Cotton palm, Arizona Fan Palm, or California Fan Palm) is a palm native to the desert oases of Central, southern and southwestern Arizona, southern Nevada, extreme northwest Mexico of northern Baja California state, and the inland deserts of Southern California, mainly the Colorado) is the only species of palm tree Arecaceae or Palmae , the palm family, is a family of flowering plants, the only family in the monocot order Arecales. There are roughly 202 currently known genera with around 2600 species, most of which are restricted to tropical, subtropical, and warm temperate climates. Most palms are distinguished by their large, compound, evergreen leaves that is native to the continental United States west of the Balcones Fault.[4]
See also
- Texas Hill Country The Texas Hill Country is a vernacular term applied to a region of Central Texas, that features tall rugged hills that consist of thin layers of soil lying ontop of either limestone or granite. It also includes the Llano Uplift and the second largest granite monadnock in the United States, Enchanted Rock, which is located 18 miles north of
- Balcones Canyonlands National Wildlife Refuge Balcones Canyonlands National Wildlife Refuge offers some of the best birdwatching and habitat left in Texas for two endangered songbirds - the black-capped vireo and the golden-cheeked warbler. Less than an hour from Austin, visitors can step off the streets into the wilds of the Texas Hill Country
- Colorado River (Texas) The Colorado River is the 18th longest river in the United States and the longest river with both its source and mouth within Texas; however its drainage basin and some of its usually dry tributaries do extend into New Mexico. The 862-mile long river flows generally southeast from Dawson County through Marble Falls, Austin, Bastrop, Smithville, La
References
- ^ Grimshaw, Thomas W.; Charles Woodruff, Jr. (1986). "STRUCTURAL STYLE IN AN EN ECHELON FAULT SYSTEM, BALCONES FAULT ZONE, CENTRAL TEXAS: GEOMORPHOLOGIC AND HYDROLOGIC IMPLICATIONS". The University of Texas The University of Texas at Austin is a public research university located in Austin, Texas, United States, and is the flagship institution of The University of Texas System. The main campus is located approximately 0.25 miles (0.40 km) from the Texas State Capitol. Founded in 1883, the university has the fifth-largest single-campus enrollment in. http://www.lib.utexas.edu/geo/balcones_escarpment/pages71-76.html. Retrieved 2008-10-27.
- ^ Hill, Robert T. Robert Thomas Hill was a significant figure in the development of American geology during the late nineteenth century and in the early part of the twentieth century. As a pioneer Texas geologist, Hill discovered and named the Comanche Series of the Lower Cretaceous, and was a lifelong student of the structure and stratigraphy of the Cretaceous (1891). "A brief description of the Cretaceous rocks of Texas and their economic uses". in E. T. Dumble. First Annual Report of the Geological Survey of Texas, 1889. Austin: State Printing Office. p. 134. http://www.lib.utexas.edu/books/landscapes/publications/txu-oclc-5235917-1/txu-oclc-5235917-1-b134a.html.
- ^ "Peak Acceleration (%g) with 10% Probability of Exceedance in 50 Years" (GIF The Graphics Interchange Format is a bitmap image format that was introduced by CompuServe in 1987 and has since come into widespread usage on the World Wide Web due to its wide support and portability). USGS The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology, geography, geology, and hydrology. The USGS is a. 2002-10. Archived from the original on 2007-06-27. http://web.archive.org/web/20070627054315rn_1/earthquake.usgs.gov/research/hazmaps/products_data/2002/2002April03/US/USpga500v4.gif.
- ^ Hogan, C. Michael (2009-01-05). "California Fan Palm: Washingtonia filifera". GlobalTwitcher.com. http://globaltwitcher.auderis.se/artspec_information.asp?thingid=90942. Retrieved 2009-07-13.
External links
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Categories: Escarpments | Geology of Texas
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Tue, 08 Jun 2010 01:04:30 GMT+00:00
IndiaCompanyNews (press release) (blog) The topography of the Texas Hill Country, formed millions of years ago when the Balcones Fault lifted and transformed the terrain, uniquely identifies and ...
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Frio Sabinal Medina Guadalupe and Pedernales Rivers and their tributary systems San Antonio and Austin Tex are located on the Coastal Plain at the edge of the Balcones fault zone Figure 30 Rio Grande and the flat lying limestone layers of the Edwards Plateau downstream from the mouth of the Pecos River Mexico on the left side of picture Photograph by V L Freeman
Dason_Whitsett
hu, 20 Aug 2009 20:14:59 GM
The house sits on the . Balcones fault. , which is actually a series of small fractures called an eschelon. It is entered from below through an open-air, covered stone stair tower that draws cool air into the house. ...
