What is the Vredefort Dome?
So, what is the Vredefort Dome and why is it important enough to be declared a World Heritage Site? Well, here’s the deal. About 2 billion years ago (that’s billion as in 1000 million) there was a catastrophic event just outside the present-day village of Vredefort, in the Orange Free State.
An enormous meteorite measuring between 10 and 15 kilometers across smashed into the ground, causing unimaginable destruction and chaos.
When all the dust had settled, a crater measuring between 200 and 300 kilometers in diameter was left behind, stretching from Welkom in the southwest to Pretoria in the northeast. At the centre of the crater was a prominent uplift – kinda like the splash-back you see when you drop a pebble into a pond.
This uplift, originally measuring about 100km across, is the Vredefort Dome. Today, much of this dome has been eroded away or covered by newer rock layers, but there is a remainder of ‘Dome Mountain Land’ which can still be seen curling around the present-day town of Parys.
Largest Impact Structure
The Vredefort Dome is the earliest and largest impact structure found on the Earth thus far. Furthermore, the impact literally turned the Earth inside out and pushed up ancient ‘basement’ rock layers that are not visible anywhere else on the planet.
And there’s more. It is surmised that the impact effectively buried the gold deposits that were present in the contemporary surface rocks, and thus protected the Witwatersrand gold fields for future generations.
So, although it is not as dramatic as the Drakensberg or as historically tangible as Robben Island, the mountain land around Parys is of considerable geological significance to the planet as a whole.
The Dome also highlights the crucial role that meteorite impacts have played in the formation of our planet, and the development of the life forms that flourish on its surface.
As The United Nations Educational, Scientific and Cultural Organisation (UNESCO) puts it: “The 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.”
“The Vredefort Dome is the oldest, largest and most deeply eroded complex meteorite impact structure in the world. 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 (impact structure) below the crater floor, thereby enabling research into the genesis and development of an astrobleme immediately post impact.”
South Africa’s 7th World Heritage Site
All the geological wonders have collectively made the Vredefort Dome a National Heritage Site and South Africa’s 7th World Heritage Site. The core World Heritage zone covers nearly 30 000ha, with three small additional sites of geological importance that lie outside the core zone.
These additional sites are: the stromatolite/basal fault plane site, the chocolate tablet breccia site and the pseudotachylite (quarry) site. The core is surrounded by 5km buffer zone, for a total area of around 70 000ha.
The UNESCO Declaration
UNESCO giveth, UNESCO can taketh away, and the The United Nations Educational, Scientific and Cultural Organisation (UNESCO) declaration has a couple of important conditions attached. I’ve quoted the final decision text below, since it is interesting to watch the World Heritage process at work.
This essentially means that that the various stakeholders responsible for the Dome have until 2007 to get their act together. I’m sure that they will do it, but it’s not going to be as easy as it sounds. Firstly, the Dome core area straddles both the North West and Free State provinces, each with its own tourism board, budget and policies.
It also falls across 5 different district municipalities and incorporates over 100 private landowners, including the national government. There are even two different conservancies operating on either side of the provincial boundary trying to promote and conserve their respective areas.
This fragmentation of the dome makes communication difficult and complicates the decision-making process, since everyone has their own agendas and priorities.
Nevertheless, one trusts that the various stakeholders will be able to put aside any partisanship and work together with the local community to establish a unified management authority, which can drive the project to a successful conclusion.
The above-mentioned UNESCO committee did indeed re-visit the site at the end of April 2008. And things were not quite going as planned. The management committee had fallen apart; stakeholders were arguing about development strategies; the site had not even been proclaimed in terms of South Africa’s heritage legislation. It was a bit of a let-down.
Challenges to Overcome
Admittedly, there were a lot of challenges to overcome. Unilateral decisions were being made by provincial authorities sitting far apart, in Mafikeng and Bloemfontein.
There were disagreements about where the visitor’s centre should be located, Vredefort or Venterskroon. Poor municipal maintenance caused raw sewerage to leak into the Vaal River. New landowners opposed the national heritage legislation. And there was a crippling lack of common vision and effective leadership.
But never fear. Although at time of writing, the committee’s report had not yet been released, there is little danger of the Dome’s World Heritage status being revoked.
UNESCO may slap a few wrists but there are few physical threats to the site, a new management authority has been set up and administrative procedures have been improved. One hopes that the Vredfort Dome will now only go from strength to strength.
By David Fleminger