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Vredefort crater
From Wikipedia, the free encyclopedia
| Vredefort Dome* | |
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| UNESCO World Heritage Site | |
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| State Party |  South Africa |
| Type | Natural |
| Criteria | viii |
| Reference | 1162 |
| Region† | Africa |
| Inscription History | |
| Inscription | 2005 (29th Session) |
| * Name as inscribed on World Heritage List. † Region as classified by UNESCO. |
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Vredefort crater is the largest verified impact crater on Earth.[1] It is located in the Free State Province of South Africa, and named after the town of Vredefort, which is situated near its centre. The site is also referred to as Vredefort dome or Vredefort impact structure. In 2005, the Vredefort Dome was added to the list of UNESCO World Heritage Sites for its geologic interest.
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The asteroid that hit Vredefort is one of the largest to ever impact Earth, estimated at over 10 km (6 miles) wide, although it is believed by many that the original size of the impact structure could have been 250 km in diameter, or possibly larger. This makes Vredefort the largest known impact structure on Earth (though the Wilkes Land crater in Antarctica, if confirmed to have been the result of an impact event, is even larger at 500 kilometers across). The crater has a diameter of roughly 300 km (186 miles), larger than the 250 km (155 miles) Sudbury Basin, and the 170 km (106 miles) Chicxulub crater. The age is estimated to be over 2 billion years (2023 ± 4 million years), impacting during the Paleoproterozoic era. It is the second oldest known crater on the Earth, a little less than three hundred millions years younger than the Suavjärvi crater in Russia.
It was originally thought that the dome in the center of the crater was formed by a volcanic explosion, but in the mid 1990s evidence revealed that it was the site of a huge bolide impact, with telltale shatter cones often discovered in the bed of the nearby Vaal River.
The Vredefort crater site is one of the few multi-ringed impact craters on Earth, though they are more common elsewhere in the solar system. Perhaps the best example is of Valhalla crater on Jupiter's moon Callisto, though Earth's Moon has a number as well. Geological processes, such as erosion and plate tectonics, have destroyed most multi-ring craters on Earth.
The nearby Bushveld Igneous Complex (BIC) was created during this same period, leading to speculation that Vredefort impactor size/kinetics were of sufficient magnitude to induce local volcanism. BIC is the location of the majority of world's known reserves of platinum group metals (PGMs).
A potentially larger but unverified crater has recently been located under the ice at Wilkes Land in Antarctica. [2]
- ^ Deep Impact - The Vredefort Dome. Hartebeesthoek Radio Astronomy Observatory (2006-08-01). Retrieved on 2007-09-19.
- ^ World's largest crater discovered (with eye candy). [1] (2006-06-03). Retrieved on 2007-09-19.
- Earth Impact Database
- Deep Impact - The Vredefort Dome
- Satellite image of Vredefort crater from Google Maps
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Cape Floral Region Protected Areas · Fossil Hominid Sites of Sterkfontein, Swartkrans, Kromdraai and Environs · iSimangaliso Wetland Park · Mapungubwe Cultural Landscape · Robben Island · uKhahlamba / Drakensberg Park · Vredefort Dome |
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