Did you know?
Only 120km south-west of Johannesburg, lies the Vredefort dome – the oldest and largest (visible) impact structure on earth. This impact structure or astrobleme dates back 2 billion years, when a meteor + -10km in diameter (about the size of table mountain) disrupted the earths surface in a devastating way. Some scientists list the impact as the “world’s greatest known single energy release event“, with enough force to bring about massive evolutionary changes. On impact it forced layers of rock outwards and downwards to form three rims of crumpled ridges that today stretch as far as Johannesburg and into the North West province. At the time, about 70 cubic kilometers of rock would have been vaporised.
It is believed that the Vredefort Dome impact event caused granite and gold to be forced to the surface, and allowed for gold to be found in Johannesburg.
It is revered by many as an important site as it provides critical evidence of the Earth’s geological history and is crucial to our understanding of the evolution of the planet. The crater stretches from Johannesburg to Welkom, with a radius of 190km or more, and is the only example of an impact site to show a full geological profile of an astrobleme below the crater floor, where most other accounts have most probably been eroded by gradual geological earth activities. Within the area, geological strata (granitic gneiss rock) comprising the middle to upper zones of the earth’s crust, developed over a period of more than 3 200 million years are exposed.
It’s difficult to understand and view the Vredefort Dome Impact. The total size of the crater can only be seen from space, but from certain view spots, and when driving into Parys (the nearest town to the the dome), you can get an idea of it, and just how massive the Vredefort Dome Impact site actually is.
For ages geologists couldn’t see eye to eye on what caused the phenomenon. After many years of debate, scientists agreed that this area was formed by a meteorite and not volcanic activity. Some evidence of the impact can be seen at a quarry at Leeukop near Parys. In the image above, you can see a cross-section of rock. The pale and medium hue’s of grey are the natural granite colour, but the dark grey band is granite that was melted by the impact which flowed, and carried chunks of unmelted granite with it. Shatter cones found in various sites, also add to the proof of a meteor impact. Shatter cones are shockwaves through the underlying rock, left behind as a result of the impact. They have a characteristic “fir tree” like pattern.
The Vredefort Dome has been listed as a Unesco World Heritage Site, but still needs to be proclaimed a South African National Heritage Site before it’s world status can be declared by Unesco.
As a resullt of the Impact, the vegetation, climate, and landscape are truelly unique and beautiful. The Vaal River that flows through this fertile land is also one of the oldest rivers on Earth. You get a sense that you’re walking in the original garden of eden – a true land before time. The Vredefort Dome is also recognised for having over 450 different species of birds and rare animals such as rooikat, aardwolf, leopard, and the endangered rock dassie. It’s an incredibly beautiful place to explore, and those wanting to view various meteor sites are recommended to go with an experienced guide. You’re bound to be impressed.
If you are interested in a Vredefort Dome Impact tour, River Walks, Rafting Trips, Hiking Trails as well as Mountain Bike Trails, please fill in the form below: