Vredefort Impact Structure

The Vredefort Dome lies in South Africa, southwest of Johannesburg, and is part of a much larger impact structure. The impact occurred about 2.02 billion years ago. Erosion over geological time has removed much of the original crater, but the exposed rocks preserve a rare cross-section through the structure and its uplifted central region. The name Vredefort Dome refers to the visible remnant, not the full original crater.

The original dimensions are difficult to establish because the structure is deeply eroded and the surviving geological features do not define a simple intact rim. NASA reports estimates of roughly 180–300 kilometres for the crater after its initial collapse and rebound. A 2022 study using impact simulations found that larger impactors or higher impact velocities than in some earlier models could better reproduce a crater around 250 kilometres across and match geological evidence. These are model-based estimates, not direct measurements of the vanished crater.

Vredefort provides evidence for studying how large impacts deform Earth's crust, generate shock-related features, and distribute impact material. UNESCO describes the property as the oldest known astrobleme and as a deeply eroded part of a larger structure. The surviving rocks and structural patterns make it an important natural record of an ancient impact, while uncertainty about the original crater's precise dimensions remains an active subject of research.