An impact crater is a circular depression in the surface of a solid astronomical body 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. Impact craters range in size from microscopic craters seen on lunar rocks returned by the Apollo Program to simple bowl-shaped depressions and vast, complex, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth.
A meteorite is a rock that originated in outer space and has fallen to the surface of a planet or moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate energy. It then becomes a meteor and forms a fireball, also known as a shooting star; astronomers call the brightest examples "bolides". Once it settles on the larger body's surface, the meteor becomes a meteorite. Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater.
An impact event is a collision between astronomical objects causing measurable effects. Impact events have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effect. When large objects impact terrestrial planets such as the Earth, there can be significant physical and biospheric consequences, as the impacting body is usually traveling at several kilometres a second, though atmospheres mitigate many surface impacts through atmospheric entry. Impact craters and structures are dominant landforms on many of the Solar System's solid objects and present the strongest empirical evidence for their frequency and scale.
Tektites are gravel-sized bodies composed of black, green, brown or grey 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 millimetres to centimetres. Millimetre-scale tektites are known as microtektites.
Boxhole is a young impact crater located approximately 180 km north-east of Alice Springs in the Northern Territory, Australia. It is 170 metres in diameter and its age is estimated to be 5,400 ± 1,500 years based on the cosmogenic 14C terrestrial age of the meteorite, placing it in the Holocene. The crater is exposed to the surface.
Crawford is an impact crater near Adelaide in South Australia, Australia.
Foelsche is a partly buried impact structure, the eroded remnant of a former impact crater. It is situated about 85 km southeast of Borroloola in the Northern Territory, Australia, and named after the nearby Foelsche River. Although little of it is exposed at the surface, and no crater shaped topography is evident, the circular nature of the feature is obvious on aeromagnetic images, a factor that led to its discovery.
Gweni-Fada is a meteorite crater in the Ennedi Plateau, Chad.
Lawn Hill ‘crater’ refers to an Ordovician impact structure, the eroded remnant of a former impact crater, situated approximately 220 km north-north-west of Mount Isa in northwestern Queensland, Australia. The site is marked by an 18 km diameter ring of dolomite hills. The origin of this circular feature was uncertain until the discovery of shatter cones and shocked quartz from uplifted rocks at the centre was reported in 1987.
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).
Rochechouart impact structure or Rochechouart astrobleme is an impact structure in France. Erosion has over the millions of years mostly destroyed its impact crater, the initial surface expression of the asteroid impact leaving highly deformed bedrock and fragments of the crater's floor as evidence of it.
The Vredefort impact structure is the largest verified impact structure on Earth. The crater, which has since been eroded away, has been estimated at 170–300 kilometres (110–190 mi) across when it was formed. The remaining structure, comprising the deformed underlying bedrock, is located in present-day Free State province of South Africa. It is named after the town of Vredefort, which is near its centre. The structure's central uplift is known as the Vredefort Dome. The impact structure was formed during the Paleoproterozoic Era, 2.023 billion years ago. It is the second-oldest known impact structure on Earth, after Yarrabubba.
Wolfe Creek Crater is a well-preserved meteorite impact crater (astrobleme) in Western Australia.
Darwin glass is a natural glass found south of Queenstown in West Coast, Tasmania. It takes its name from Mount Darwin in the West Coast Range, where it was first reported, and later gave its name to Darwin Crater, a probable impact crater, and the inferred source of the glass.
Henbury Meteorites Conservation Reserve is a protected area in the Northern Territory of Australia located in the locality of Ghan.
Darwin Crater is a suspected meteorite impact crater in Western Tasmania about 26 km (16 mi) south of Queenstown, just within the Franklin-Gordon Wild Rivers National Park. The crater is expressed as a rimless circular flat-floored depression, 1.2 km (0.75 mi) in diameter, within mountainous and heavily forested terrain. It is east of the West Coast Range and the former North Mount Lyell Railway formation.
Ramgarh crater, also known as Ramgarh structure, Ramgarh Dome and Ramgarh astrobleme, is a meteor impact crater of 3.5 kilometres (2.2 mi) diameter in Kota plateau of Vindhya Range located adjacent to Ramgarh village in Mangrol tehsil of Baran district in Rajasthan state of India. When formally accepted as the third crater in India, its diameter size would be between the two already confirmed craters in India - Dhala in Madhya Pradesh with 14 km diameter and Lonar in Buldhana district of Maharashtra with 1.8 km diameter.
