Some 2 billion years ago a meteorite 10 kilometres in diameter hit the earth about 100km southwest of Johannesburg, creating an enormous impact crate. This area, near the town of Vredefort in the Free State, is known as the Vredefort Dome. It is a natural heritage site, inscribed in 2005, situated in the Free State and North West.
Vrederfort Dome, approximately 120km south west of Johannesburg, is a representative part of a larger meteorite impact structure, or astrobleme.
Dating back 2, 023 million years, it is the oldest astrobleme found on earth so far. With a radius of 190km, it is also the largest and the most deeply eroded. Vredefort Dome bears witness to the world's greatest known single energy release ever, which caused devastating global change, including, according to some scientists, major evolutionary changes. It provides critical evidence of the earth's geological history and is crucial to our understanding of the evolution of the planet. Despite their importance to the planet's history, geological activity on the earth's surface has led to the disappearance of evidence from most impact sites and Vrederfort is the only example on earth to provide a full geological profile of an astrobleme below the crater floor.
The meteorite, larger than Table Mountain, caused a thousand-megaton blast of energy. The impact would have vaporised about 70 cubic kilometres or rock - and may have increased the earth's oxygen levels to a degree that made the development of multicellular life possible.
The world has about 130 crater structures of possible impact origin.The Vredefort Dome is among the top three, and is the oldest and largest clearly visible meteorite site in the world. The original crater, now eroded away, was probably 250 to 300 kilometres in diameter. It was larger than the Sudbury impact structure in Canada, about 200km in diameter.
At 2 billion years old, Vredefort is far older than the Chixculub structure in Mexico which, with an age of 65 million years, is the site of the impact that led to the extinction of dinosaurs.
Vredefort's original impact scar measures 380km across and consists of three concentric circles of uplifted rock. They were created by the rebound of rock below the impact site when the asteroid hit. Most of these structures have eroded away ad are no longer clearly visible. The inner circle, measuring 180km, is still visible and can be seen in the beautiful range of hills near Parys and Vredefort. It is this area that was named a World Heritage Site.
Justification for Inscription
Vredefort Dome is the oldest, largest, and most deeply eroded complex meteorite impact structure in the world. It is the site of the world's greatest single, known energy release event. It contains high quality and accessible geological (outcrop) sites which demonstrate a range of geological evidences of a complex meteorite impact structure. The rural and natural landscapes of the serial property help portray the magnitude of the ring structures resulting from the impact. The serial nomination is considered to be a representative sample of a complex meteorite impact structure. A comprehensive comparative analysis with other complex meteorite impact structures demonstrated that it is the only example on earth providing a full geological profile of an astrobleme below the crater floor, thereby enabling research into the genesis and development of an astrobleme immediately post impact.
Many activities can be enjoyed in the area on the Dome Bergland Meander. From river rafting, river tubing, abseiling, horse riding, mountain biking, archery or walking.