Some two billion years ago, an asteroid the size of Cape Town’s Table Mountain slammed into Earth at a speed of 30,000 kilometres per hour, forming a 300km-wide crater. The impact at Vredefort, 10km south of Parys, vaporized the asteroid and part of the Earth’s crust, melting, pulverizing and shattering rocks for kilometres around. It also forced rocks beneath the impact area briefly down before these rebounded, raising and upending rock layers to form a dome structure. Even though the Earth’s surface has eroded about 10km since the impact, the weathered concentric rings of this dome can still be seen, forming the hills around Parys. The rim of the crater, originally up to 150km away, has not survived the elements, though it’s thanks to the downward sagging of the gold-bearing layers around the dome, caused by the impact, that the richest source of gold in the world was preserved from erosion before the first gold diggers discovered these layers in Johannesburg, in 1886.
The dome area is best experienced on a tour, which takes in the view of the dome remnants, and tracks down strange melt rock formations.
A well-designed new visitor centre on the outskirts of Vredefort on the road to Parys has an introductory film, 3D models, and interactive displays about the Vredefort impact, the solar system, meteorites, asteroids, craters and the environmental consequences of impacts.