Vredefort Dome, approximately 120km south west of Johannesburg,
is a representative part of a larger meteorite impact structure,
or astrobleme and has been declared South Africas seventh
World Heritage Site (2005).
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
worlds 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 earths geological history
and is crucial to our understanding of the evolution of the planet.
Despite their importance to the planets history, geological
activity on the earths 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.
When visiting the area you will notice small hills in a large dome
shape with beautiful valleys between them.
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
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.
Several landowners in the region have come together to form the
Vredefort Dome Conservancy.
The Conservancy is one of the province's prime adventure tourism
sites with numerous tour operators and accommodation facilities
catering for the needs of campers, hikers, rock climbers, canoeists
and white water rafters.
It is possible to drive, cycle or walk around parts of the Dome
which are either open to the public or can be accessed by permission.
Parys Info & Tourism:
Tel (056) 811 4000
c/o Buiten and Water Street, Parys
How to get there
The dome is situated about 120 km south west of Johannesburg just
off the N1.