Vredefort: the largest verified impact crater on Earth

About two billion years ago an asteroid an estimated 20–25 km across struck what is now the Free State of South Africa, blasting out a crater roughly 250–300 km wide — larger than the impact that ended the dinosaurs. Two billion years of erosion have since worn it down to the Vredefort Dome, a ~70 km ring of upturned rock and the largest verified impact structure on Earth.

By W. Viljoen · Published 21 June 2026

On the map

Original crater — roughly 300 km across at the moment of impact
Vredefort Dome — the ~70 km eroded centre that survives today

Earth's biggest impact

Asked to picture the largest asteroid impact in Earth's history, most people think of the dinosaurs — the Chicxulub crater off Mexico, around 180 km across. The largest one we can actually confirm is older, bigger, and sits in the Free State of South Africa.

When it formed about 2.02 billion years ago, the Vredefort crater was roughly 250 to 300 kilometres wide. It is the largest verified impact structure on Earth, and the second-oldest we know of — only the Yarrabubba structure in Western Australia, at about 2.23 billion years, is older.

What hit, and how hard

The impactor is estimated at 20–25 kilometres across — recent modelling revised it upward from older figures nearer 10 km — striking at somewhere between 15 and 25 kilometres per second, in one of the greatest bursts of energy in the planet's history.

Its original size is a reconstruction, not a measurement: two billion years of erosion stripped away the rim, so estimates of the crater's diameter range from about 170 km up to 300 km, with most work clustering around 250–300 km.

The two circles on the map

The large ring is the original crater — the full scar at the moment of impact. The small ring nested inside it is all that survives today: the Vredefort Dome, about 70 kilometres of upturned, deformed rock — the central peak that rebounded after the strike and then froze in place. It has been a UNESCO World Heritage Site since 2005.

Drag the structure across the map to feel the gap between the two. The outer circle is the size of the wound; the inner circle is the part you could still walk across today.

To scale

The original crater covers roughly 70,000 km². That is about the size of Belgium and the Netherlands combined, more than twice the area of Lesotho, and almost four times the size of Gauteng — South Africa's most populous province dropped into a single asteroid's mark with room to spare.

Even the surviving dome, the 70 km inner ring, is larger than Luxembourg. You can drive through the middle of the largest confirmed asteroid impact on the planet and never notice — that is how big two billion years and 300 kilometres really are.

Why it's worn so flat

Unlike Chicxulub, which lies buried and largely intact, Vredefort is deeply eroded — and that is exactly why geologists prize it. Erosion has sliced the structure open, so its deep interior can be read straight from the surface, something no younger, intact crater allows.

Where it is

The structure is centred near the town of Vredefort in the Free State, at roughly 27.0°S, 27.5°E, with the riverside town of Parys sitting inside it. It lies about 120 kilometres southwest of Johannesburg — close enough for a day trip into the oldest and largest asteroid scar we can confirm anywhere on Earth.