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Vredefort Dome: Free State
Province, South Africa.
Date of Inscription: 2005.
Description: Vredefort 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 event, 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
Vredefort is the only example on earth to provide a full geological profile of an
astrobleme below the crater floor. (Source: UNESCO)
Vredefort Dome in the Free State, South Africa: The Vredefort dome is the oldest
and largest meteorite impact site (Asrobleme) in the world. Formed an estimated 2000
million years ago when a gigantic meteorite (larger than Table Mountain) hit the earth
close to where Vredefort is today. The force of the impact opened up a crater, which is
still visible, and is about 40km in diameter.
When visiting the area you will notice small hills in a large dome shape with beautiful
valleys between them. Evidence has been found by geologists that the cause of this
upliftment was an extreme impact event, caused by an asteroid some 10 kilometres in
diameter. The ring of hills we see now are the eroded remains of a dome created by the
rebound of the rock below the impact site after the asteroid hit. The original crater, now
eroded away, is estimated to have been 250 - 300 kilometres in diameter. Some 70 cubic
kilometres of rock would have been vaporised in the impact.
The Vredefort structure is currently regarded the biggest and oldest clearly visible
impact structure on Earth. It just beats the Sudbury impact structure in Canada for this
ranking. The Sudbury structure is some 200 km in diameter and is estimated to be 1.85
billion years old.
Within the ring of hills at Vredefort is found granitic gneiss rock. The force of the
impact produced deep fractures in the underlying rock. Rock melted by the impact flowed
down into the cracks, producing what are now exposed as ridges of hard dark rock - the
granophyre dykes. This contrasts with normal geological dykes, where molten rock from
deeper in the earth has flowed upwards through cracks.
Many activities can be enjoyed in the area. From river rafting, river tubing, abseiling,
horse riding, mountain biking, archery or walking. Or visits to Anglo Boer War sites, the
the largest wild olive forest in South Africa at Venterskroon, or a visit to a distillery
where traditional South African "witblits" (extremely strong spirits) is made |
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With 20 National Parks
(including two of the world's most famous wildlife reserves, the Kruger Park and Kgalagadi Transfrontier Park)
numerous private game reserves, your trip to South Africa would be incomplete without
experiencing a South African wildlife safari .... |
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