An impact crater is a 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 are typically circular, though they can be elliptical in shape or even irregular due to events such as landslides. 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.
Meteor Crater or Barringer Crater is an impact crater about 37 mi (60 km) east of Flagstaff and 18 mi (29 km) west of Winslow in the desert of northern Arizona, United States. The site had several earlier names, and fragments of the meteorite are officially called the Canyon Diablo Meteorite, after the adjacent Canyon Diablo.
The Sudbury Basin, also known as Sudbury Structure or the Sudbury Nickel Irruptive, is a major geological structure in Ontario, Canada. It is the third-largest known impact crater or astrobleme on Earth, as well as one of the oldest. The crater was formed 1.849 billion years ago in the Paleoproterozoic era.
Ames crater is a meteorite crater (astrobleme) in Major County, Oklahoma, United States. Ames, Oklahoma is near the center of the structure, which is 30 miles (48 km) southwest of Enid, Oklahoma. Buried under a thick layer of sediment, it was not discovered until 1991. Subsequent drilling within the crater found a large amount of oil and gas. It is one of the largest of six meteor craters associated with oil-producing formations in the United States.
The Glasford crater, also known as the Glasford Disturbance, Glasford Structure, and Glasford Cryptoexplosion Structure, is a buried impact crater in southern Peoria County, Illinois, in the United States. It is one of two known meteor craters in Illinois.
Kaali is a group of nine meteorite craters in the village of Kaali on the Estonian island of Saaremaa. Most recent estimates put its formation shortly after 1530–1450 BC. It was created by an impact event and is one of the few impact events that has occurred in a populated area.
Lappajärvi is a lake in Finland, in the municipalities of Lappajärvi, Alajärvi and Vimpeli. It is formed in a 23 km (14 mi) wide, partly eroded meteorite impact crater. The lake is part of Ähtävänjoki basin together with Lake Evijärvi that is located downstream (north) of it.
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 Rock Elm Disturbance is an impact crater in Pierce County, Wisconsin, United States, roughly 40 kilometres (25 mi) southwest of Menomonie. The disturbance is named for Rock Elm, Wisconsin, a nearby town.
Viewfield is an impact crater in Saskatchewan, Canada. It is 2.5 kilometres (1.6 mi) in diameter and the age is estimated to be 190 ± 20 million years. The crater is not exposed at the surface.
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.
The Slate Islands are a small archipelago in Lake Superior, Ontario, Canada, about 12 kilometres (7.5 mi) south of the town of Terrace Bay. The island group, consisting of 15 islands in total, was created by a meteorite impact which formed a crater about 32 km (20 mi) wide. In 1985, the Ontario government established the Slate Islands as a natural environment provincial park. The islands are notable for having Ontario's largest herd of boreal woodland caribou.
The Lac Wiyâshâkimî, also called the Clearwater Lakes in English and Allait Qasigialingat by the Inuit, are a pair of annular lakes and impact structures on the Canadian Shield in Quebec, Canada, near Hudson Bay.
As of June 2018, 12 confirmed impact structures have been found in Finland. They are listed below, sorted by original diameter.
