Vredefort impact structure
The Vredefort impact structure is one of the largest verified impact structures 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 million (± 4 million) years ago. It is the second-oldest known impact structure on Earth, after Yarrabubba.
In 2005, the Vredefort Dome was added to the list of UNESCO World Heritage Sites for its geologic interest.