Long Durational Natural Phenomenon

Existence of Vredefort Crater

Duration: Approximately 2.023 billion years (± 4 million years)

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Cover photograph Public Domain Júlio Reis

Vredefort crater is the largest verified impact crater on Earth, more than 300 km across when it was formed. What remains of it is located in the present-day Free State Province of South Africa and named after the town of Vredefort, which is situated near its centre. Although the crater itself has long since eroded away, the remaining geological structures at its centre are known as the 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. 

Vaal river at the Vredefort Meteor Impact Site. Photograph CC BY 2.0 Abri le Rou

The asteroid that hit Vredefort is estimated to have been one of the largest ever to strike Earth, thought to have been approximately 5–10 km in diameter. The original crater was estimated to have a diameter of roughly 300 km, although this has been eroded away. It would have been larger than the 250 km Sudbury Basin and the 180 km Chicxulub Crater. The remaining structure, the "Vredefort Dome," consists of a partial ring of hills 70 km in diameter, and are the remains of a dome created by the rebound of rock below the impact site after the collision.

The crater's age is estimated to be 2.023 billion years (± 4 million years), which places it in the Paleoproterozoic Era. It is the second-oldest known crater on Earth, a little less than 300 million years younger than the Suavjärvi Crater in Russia. 

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