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Impact Field Studies Group
The Impact Field Studies Group (IFSG) was a scientific organization emphasizing geologic field research of suspected and confirmed sites of impact craters and impact structures. The group is composed of researchers, professionals and students involved in study of impact sites. IFSG's web site is hosted by the Department of Earth and Planetary Sciences at University of Tennessee, Knoxville. Impact Database IFSG member David Rajmon maintains for the organization a list which was originally called the Suspected Earth Impact Sites (SEIS) list from 2004 to 2009. It was then renamed to simply the Impact Database. The list classifies impact sites as confirmed, most probable, probable, possible, improbable, rejected and proposed (unevaluated). The list retains rejected entries because they tend to be submitted repeatedly. The IFSG Impact Database accepts submissions of proposed new impact sites. However, they require submitters do some significant homework as listed below first. * T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Impact Crater
An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Lunar impact craters range from microscopic craters on lunar rocks returned by the Apollo Program and small, simple, bowl-shaped depressions in the lunar regolith to large, complex, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth. Impact craters are the dominant geographic features on many solid Solar System objects including the Moon, Mercury, Callisto, Ganymede and most small moons and asteroids. On other planets and moons that experience more active surface geological processes, such as Earth, Venus, Europa, Io and Titan, visible impact craters are less common because they become eroded ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sierra Madera Crater
Sierra Madera crater is a meteorite crater (astrobleme) in southwestern Pecos County, Texas, United States. The central peak of the rebound structure of the impact crater rises above the surrounding land. The peak is visible from U.S. Highway 385 between Fort Stockton, Texas and Marathon, Texas. The Sierra Madera crater is located on private property on the La Escalera Ranch. It is in diameter and the age is estimated to be less than 100 million years (Cretaceous or younger). Apollo 17's Gene Cernan and Jack Schmitt did some of their geologic training here. See also *Odessa Meteor Crater *Marquez crater * Barringer Meteor Crater, Arizona *Trans-Pecos The Trans-Pecos, as originally defined in 1887 by the Texas geologist Robert T. Hill, is the portion of Texas that lies west of the Pecos River. The term is considered synonymous with Far West Texas, a subdivision of West Texas. The Trans-Peco ... * Pecos River * Llano Estacado References External linksGeology of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eugene Merle Shoemaker
Eugene Merle Shoemaker (April 28, 1928 – July 18, 1997) was an American geologist. He co-discovered Comet Shoemaker–Levy 9 with his wife Carolyn S. Shoemaker and David H. Levy. This comet hit Jupiter in July 1994: the impact was televised around the world. Shoemaker also studied terrestrial craters, such as Barringer Meteor Crater in Arizona, and along with Edward Chao provided the first conclusive evidence of its origin as an impact crater. He was also the first director of the United States Geological Survey's Astrogeology Research Program. He was killed in a car accident while visiting an impact crater site in Australia. After his death, some of his ashes were carried to the Moon with the Lunar Prospector mission. Early life and formal education Shoemaker was born in Los Angeles, California, the son of Muriel May (née Scott), a teacher; and George Estel Shoemaker, who worked in farming, business, teaching, and motion pictures. His parents were natives of Nebraska. D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock Metamorphism
Shock metamorphism or impact metamorphism describes the effects of shock-wave related deformation and heating during impact events. The formation of similar features during explosive volcanism is generally discounted due to the lack of metamorphic effects unequivocally associated with explosions and the difficulty in reaching sufficient pressures during such an event. Effects Mineral microstructures Planar fractures Planar fractures are parallel sets of multiple planar cracks or cleavages in quartz grains; they develop at the lowest pressures characteristic of shock waves (~5–8 GPa) and a common feature of quartz grains found associated with impact structures. Although the occurrence of planar fractures is relatively common in other deformed rocks, the development of intense, widespread, and closely spaced planar fractures is considered diagnostic of shock metamorphism. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nevada Test Site
The Nevada National Security Site (N2S2 or NNSS), known as the Nevada Test Site (NTS) until 2010, is a United States Department of Energy (DOE) reservation located in southeastern Nye County, Nevada, about 65 miles (105 km) northwest of the city of Las Vegas. Formerly known as the Nevada Proving Grounds, the site was established in 1951 for the testing of nuclear devices. It covers approximately 1,360 square miles (3,500 km2) of desert and mountainous terrain. Nuclear weapons testing at the site began with a 1-kiloton-of-TNT (4.2 TJ) bomb dropped on Frenchman Flat on January 27, 1951. Over the subsequent four decades, over 1,000 nuclear explosions were detonated at the site. Many of the iconic images of the nuclear era come from the site. During the 1950s, the mushroom clouds from the 100 atmospheric tests could be seen from almost away. The city of Las Vegas experienced noticeable seismic effects, and the mushroom clouds, which could be seen from the downtown ho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wells Creek Crater
Wells Creek is an impact crater located near Cumberland City, Tennessee. It is in diameter and the age is estimated to be (million years old), placing it in the Jurassic or a neighboring period. The crater is exposed to the surface. The center of the crater contains some of the finest shatter cone Shatter cones are rare geological features that are only known to form in the bedrock beneath meteorite impact craters or underground nuclear explosions. They are evidence that the rock has been subjected to a shock with pressures in the rang ...s in the world. Many have been collected and are on display around the world. Gallery References External links Wells Creek Craterat Tennessee Landforms Wells Creek Impact Structureat Crater Explorer Impact craters of the United States Mesozoic impact craters Landforms of Houston County, Tennessee Landforms of Stewart County, Tennessee {{Earth-crater-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kentland Crater
The Kentland structure, also known as the Kentland crater or the Kentland disturbed area, is an impact structure located near the town of Kentland in Newton County, Indiana, United States. It was discovered about 1880 when two farmers began to quarry crushed rock there. The presence of shatter cones and deformed bedrock led geologists to conclude by the late 1960s that the Kentland structure is a deeply eroded impact structure, rather than volcanic in origin. Deformation at the site is so great that vertical contacts between normally horizontal rock formations of different ages are common. The structure itself is a circular dome, about in diameter, deeply eroded and buried in glacial debris. Its age is estimated to be less than 97 million years (Cretaceous or younger). The Shakopee dolomite at the center of the structure is about 450 million years old (Ordovician period) and is uplifted about 2,000 feet higher than the level of the same rock in the surrounding area. The entire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA), to give the U.S. space development effort a distinctly civilian orientation, emphasizing peaceful applications in space science. NASA has since led most American space exploration, including Project Mercury, Project Gemini, the 1968-1972 Apollo Moon landing missions, the Skylab space station, and the Space Shuttle. NASA supports the International Space Station and oversees the development of the Orion spacecraft and the Space Launch System for the crewed lunar Artemis program, Commercial Crew spacecraft, and the planned Lunar Gateway space station. The agency is also responsible for the Launch Services Program, which provides oversight of launch operations and countdown management f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flynn Creek Crater
Flynn Creek crater is an impact crater situated in Jackson County, Tennessee, approximately 8 km south of Gainesboro. Description The impact crater was formed approximately 360 million years ago as a shallow, saucer-shaped crater, in diameter and about deep. A large central hill, highly deformed rim strata, and a breccia lens in thickness were produced during formation. Over of flat lying Middle and Upper Paleozoic limestone and dolomite were brecciated and mixed to a depth of , and at least half of the breccia was ejected from the crater. The remaining breccia contains fragments ranging in size from small grains to megabreccia blocks long. Undisturbed strata lie below the original crater floor. In the middle of the crater, a sequence of steeply-dipping, folded, faulted, and brecciated Middle Ordovician limestone and dolomite has been uplifted to form a large central hill. Rock of the Knox group in the central uplift are raised above their normal position and l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Impact Structure
An impact structure is a generally circular or craterlike geologic structure of deformed bedrock or sediment produced by impact on a planetary surface, whatever the stage of erosion of the structure. In contrast, an impact crater is the surface expression of an impact structure. In many cases, on Earth, the impact crater has been destroyed by erosion, leaving only the deformed rock or sediment of the impact structure behind.Neuendorf, K.K.E., J.P. Mehl Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. This is the fate of almost all old impact craters on Earth, unlike the ancient pristine craters preserved on the Moon and other geologically inactive rocky bodies with old surfaces in the Solar System. Impact structure is synonymous with the less commonly used term astrobleme meaning "star wound". In an impact structure, the typical visible and topographic expressions of an impact crater are no long ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middlesboro Crater
The Middlesboro crater (or astrobleme) is a meteorite crater in Kentucky, United States. It is named after the city of Middlesborough (both spellings are used), which today occupies much of the crater. The crater is approximately 3 miles (about 5 km) wide and its age is estimated to be less than 300 million years (Permian). The impactor is estimated to have been about 100 m in diameter. History The Middlesboro crater is located in the Appalachian Mountains, between the Cumberland Mountains and Pine Mountain. It forms part of the string of geological features that made the Cumberland Gap a critical westward passage during the settlement of Kentucky and the Ohio Valley in the late 18th and early 19th centuries. Settlements The town of Middlesboro, built in the crater, was established in 1886 to exploit iron and coal deposits, although the town's founder, Alexander A. Arthur, apparently did not know of the crater's extraterrestrial origin. K. J. Englund and J. B. Roen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous–Paleogene Boundary
The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K–T) boundary, is a geological signature, usually a thin band of rock containing much more iridium than other bands. The K–Pg boundary marks the end of the Cretaceous Period, the last period of the Mesozoic Era, and marks the beginning of the Paleogene Period, the first period of the Cenozoic Era. Its age is usually estimated at around 66 million years, with radiometric dating yielding a more precise age of 66.043 ± 0.011 Ma. The K–Pg boundary is associated with the Cretaceous–Paleogene extinction event, a mass extinction which destroyed a majority of the world's Mesozoic species, including all dinosaurs except for birds. Strong evidence exists that the extinction coincided with a large meteorite impact at the Chicxulub crater and the generally accepted scientific theory is that this impact triggered the extinction event. The word "Cretaceous" is derived from the Latin "creta" (ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
