An impact crater is a depression in the surface of a planet, moon, or other solid body in the Solar System or elsewhere, formed by the hypervelocity impact of a smaller body. 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. Impact craters range from small, simple, bowl-shaped depressions to large, complex, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth.
Tektites are gravel-sized bodies composed of black, green, brown, or gray natural glass formed from terrestrial debris ejected during meteorite impacts. The term was coined by Austrian geologist Franz Eduard Suess (1867–1941), son of Eduard Suess. They generally range in size from millimeters to centimeters. Millimeter-scale tektites are known as microtektites.
Acraman crater is a deeply eroded impact crater in the Gawler Ranges of South Australia. Its location is marked by Lake Acraman, a circular ephemeral playa lake about 20 kilometres (12 mi) in diameter. The discovery of the crater and independent discovery of its ejecta were first reported in the journal Science in 1986. The evidence for impact includes the presence of shatter cones and shocked quartz in shattered bedrock on islands within Lake Acraman.
Dalgaranga crater is a small meteorite impact crater located on Dalgaranga pastoral station 75 km northwest of Mount Magnet in Western Australia. It is only 24 m in diameter and 3 m deep, making it Australia's smallest impact crater. Though discovered in 1921, it was not reported in the scientific literature until 1938. The bedrock at the site is weathered Archaean granite of the Yilgarn Craton. The discovery of fragments of mesosiderite stony-iron meteorite around the crater confirms an impact origin, making this crater unique as the only one known to have been produced by a mesosiderite projectile.
Flaxman is a meteorite impact site in South Australia, Australia.
Goat Paddock is a 5 km-diameter near-circular bowl-shaped depression in a range of gently dipping Proterozoic sandstone in the Kimberley Region of northern Western Australia, 106 km west-southwest of Halls Creek. It is interpreted as an ancient meteorite impact crater, the evidence including breccia containing melted rocks, silica glass, shatter cones and shocked quartz. Drilling shows that the crater is filled with about 200 m of ancient lake sediments containing Early Eocene pollen, this age thus giving a minimum estimate for the age of the crater itself. The crater is not perfectly circular, but slightly elongated in a north–south direction, suggesting that the projectile struck at low angle from either the north or south.
Mistastin crater is a meteorite crater in Labrador, Canada which contains the roughly circular Mistastin Lake. The lake is approximately 16 km (9.9 mi) in diameter, while the estimated diameter of the original crater is 28 km (17 mi). The age of the crater is calculated to be 36.6 ± 2 million years (Eocene).
Mount Toondina crater is an impact structure, the eroded remnant of a former impact crater, located in northern South Australia in the locality of Allandale Station about 24 km (15 mi) south of the town of Oodnadatta. Mount Toondina is the high point of a circular topographic feature rising out of an otherwise relatively flat desert area of the Eromanga Basin. An impact origin was first suggested in 1976, challenging the earlier diapir hypothesis, and strongly supported by subsequent studies. A geophysical survey using gravity methods indicates an internal structure typical of complex impact craters, including an uplifted centre, and suggests that the original crater was about 3–4 km in diameter. The crater must be younger than the Early Cretaceous age of the rocks in which it is situated, but otherwise is not well dated. It has clearly undergone significant erosion since the impact event.
Rochechouart crater is an impact crater in France. The initial crater shape and structure has been lost by erosion and there is no crater visible on site; therefore it is more accurately described as Rochechouart impact structure.
Roter Kamm is a meteorite crater, located in the Sperrgebiet, within the Namibian section of the Namib Desert, approximately 80 kilometres (50 mi) north of Oranjemund and 12 kilometres (7.5 mi) southwest of Aurus Mountain in the ǁKaras Region. The crater is 2.5 kilometres (1.6 mi) in diameter and is 130 metres (430 ft) deep. The age is estimated at 4.81 ± 0.5 Ma, placing it in the Pliocene. The crater is exposed at the surface, but its original floor is covered by sand deposits at least 100 metres (330 ft) thick.
Shoemaker is an impact structure, the deeply eroded remnant of a former impact crater, situated in arid central Western Australia, about 100 km (62 mi) north-northeast of Wiluna. It is named in honour of planetary geologist Eugene Shoemaker.
Spider is an impact structure, the deeply eroded remnant of a former impact crater, situated in the Kimberley region of northern Western Australia, 18 km east of the Mount Barnett Roadhouse on the Gibb River Road. Due to very rugged terrain the site is effectively inaccessible. The name is derived from the visually striking spider-like radiating ridges of quartzite prominently visible from the air or on satellite images.
Strangways is a large impact structure, the eroded remnant of a former impact crater, located in the Northern Territory of Australia about 65 kilometres (40 mi) east-south-east of the town of Mataranka. It was named after the nearby Strangways River. The location is remote and difficult to access. Its age has been determined as approximately 646 Ma.
Tookoonooka is a large meteorite impact crater (astrobleme) situated in South West Queensland, Australia. It lies deeply buried within Mesozoic sedimentary rocks of the Eromanga Basin and is not visible at the surface.
The geology of the Moon is quite different from that of Earth. The Moon lacks a true atmosphere, which eliminates erosion due to weather. It does not have any known form of plate tectonics, it has a lower gravity, and because of its small size, it cooled faster. The complex geomorphology of the lunar surface has been formed by a combination of processes, especially impact cratering and volcanism. The Moon is a differentiated body, with a crust, mantle, and core.
Amelia Creek crater is an impact structure, the eroded remnant of a former impact crater, located in the Davenport Range, Northern Territory, Australia. It lies within a low range of Paleoproterozoic sedimentary and volcanic rocks, which are extensively folded and faulted, thus making an eroded impact crater difficult to recognize. It was only discovered by the identification of shatter cones near its centre. The central shatter cone locality is surrounded by a 20 by 12 km area of anomalous deformation, the asymmetry being possibly related to very oblique impact, but may be at least partly due to the pre-existing structural complexity of the rocks. This deformed zone gives the best estimate for the original size of the crater. Impact took place after folding of the Paleoproterozoic rocks but before deposition of Neoproterozoic and Cambrian rocks which overlie them, thus constraining the impact event to the interval between about 1660 and 600 Ma.
Secondary craters are impact craters formed by the ejecta that was thrown out of a larger crater. They sometimes form radial crater chains. In addition, secondary craters are often seen as clusters or rays surrounding primary craters. The study of secondary craters exploded around the mid-twentieth century when researchers studying surface craters to predict the age of planetary bodies realized that secondary craters contaminated the crater statistics of a body's crater count.
Matt Wilson is a recently confirmed impact crater, elliptical in shape and situated in Gregory National Park about 17 kilometres (11 mi) north of the Victoria River Roadhouse in the Northern Territory, Australia. Its size is 7.5 by 6.3 kilometres, with its long axis trending northeast–southwest.
Hesperia Planum is a broad lava plain in the southern highlands of the planet Mars. The plain is notable for its moderate number of impact craters and abundant wrinkle ridges. It is also the location of the ancient volcano Tyrrhena Mons. The Hesperian time period on Mars is named after Hesperia Planum.
