The Balcones Fault Zone is a tensional structural system in Texas Texas ( /ˈtɛksəs/ ) is the second largest U.S. state in both area and population, and the largest state in the contiguous United States. Located in the South Central United States, Texas is bordered by Mexico to the south, New Mexico to the west, Oklahoma to the north, Arkansas to the northeast, and Louisiana to the east. Texas has an area of 26 (USA The United States of America is a federal constitutional republic comprising fifty states and a federal district. The country is situated mostly in central North America, where its 48 contiguous states and Washington, D.C., the capital district, lie between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south) that runs approximately from the southwest part of the state near Del Rio, Texas Del Rio is the principal city of the Del Rio Micropolitan Statistical Area, which includes all of Val Verde County; the micropolitan area had an estimated population of 50,000 in 2007. Located across from Del Rio, in the Mexican state of Coahuila, is the city of Ciudad Acuña 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 122,222. It is the 26th largest city by population in Texas, and 195th in the US. The Waco Metropolitan Statistical Area consists of McLennan County and has a population of 228,123 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, grabens A graben is a depressed block of land bordered by parallel faults. Graben is German for ditch, 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 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 U.S. 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 any particulate matter that can be transported by fluid flow, and which eventually is deposited. 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 Ma. The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words μείων and καινός (kainos, “new”) and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows epoch. This activity was related to subsidence In geology, engineering, surveying, and orthopedic surgery, 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. There are several types of subsidence, listed below in order of increasing scale: of the Texas Coastal Plain, 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 recorded with a seismometer, also known as a seismograph. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower earthquakes being in the United States.[3]
The surface expression of the fault is the Balcones Escarpment In geomorphology, an escarpment is a transition zone between different physiogeographic provinces that involves a sharp, steep elevation differential, characterized by a cliff or steep slope. Usually escarpment is used interchangeably with scarp . But some sources differentiate the two terms, where escarpment refers to the margin between two, which forms the eastern boundary of the Texas Hill Country The Texas Hill Country is a region of Central Texas, USA, that features rolling, somewhat rugged, hills that consist primarily of limestone. 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 Fredericksburg. The Hill Country reaches into portions 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. The cave is also home to Wonder World amusement park 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. Frequently, 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, 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 and the inland deserts of Southern California) is the only species of palm tree Palm or Palmae or Panamea , 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 that is native to the continental United States west of the Balcones Fault.[4]
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 1 mile (1.6 km) from the Texas State Capitol. UT Austin was named one of the original eight Public Ivy institutions. Founded in 1883,. http://www.lib.utexas.edu/geo/balcones_escarpment/pages71-76.html. Retrieved on 2008-10-27.
- ^ Hill, Robert T. (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. 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 on 2009-07-13.
External links
Categories: Escarpments | Geology of Texas
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Newstreamz San Marcos
Even more family fun can be had at Wonder World Park (1000 Prospect Street) where the Balcones Fault Line Cave is cool in temperature and just plain cool to ...
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Balcones fault zone one near Austin and two west of San Antonio A fourth structure may also be present near New Braunfels Figure 1 Principal features of the San Marcos case study area Figure 2 Simplified geologic map of San Marcos area showing step fault zones and associated faulting in the area between Figure 3 Block diagram of en echelon step fault zones showing
kokopelliwoman
Fri, 09 Nov 2007 11:03:00 GM
the hill country is a gentle remnant of the ancient . balcones fault. , which lies thirty miles to the east of elgin. the north-south . fault. line exposes a hundred mile long slash of granite, marble, and fossil-laden limestone formations, ...
