Page 31 - FWG Issue 6 July 2024

Estate News

Crater radius Crater from space Vredefort crater

The meteorite penetrated the Earth down Looking at all the rocks around the dome But the most staggering result of this impact
to about 15km before exploding at about it’s easy to spot the different geological is that it pushed gold from the surface
20 000 degrees centigrade and turning to formations and also the way they have been where it lay... to a ridge safe underground
gas. It created a huge upheaval – a pressure altered by the impact of the meteorite. The where it would be discovered billions of
dome roared up from deep down and made rocks have been shocked and melted and years later and would change the future of
a dome on the Earth’s surface This collapsed then, with time, eroded. South Africa forever.
very suddenly leaving the centre of the
crater. ‘The tremendous shock of the impact would If the meteorite had not hit – then the gold
have triggered earthquakes, volcanoes would have been on the Earth’s surface
But those rocks that were deep down were and there would have been a massive and would have been eroded over time.
thrust upwards so the Earth was actually restructuring of low-lying areas with these Nobody would have known there was gold
turned inside out. These rocks preserve a giant tsunamis that would be 10 times in the area.
record of almost one-third of Earth’s history higher than an earthquake based tsunami,’
as the Earth’s erosional cycles are exposed says Professor Gibson. Gold was discovered in 1887 in the western
for everyone to see. Geologists from all over corner of the Vredefort Dome. The town
the world head to Vredefort specifically for Another astonishing consequence of became a booming agricultural post on the
this reason. the impact is that the surrounding hills, important north south road leading to the
which would have been around 15km goldfields.
Graeme Addison runs tours on the ancient underground, rotated to above ground in
Vaal River, which has a history all of its own minutes after the collision, which would Meanwhile 120km away – the farm of
due to the crater. have peaked at 14 on the Richter scale today. Langlaagte was developing into the city of
gold – Johannesburg. Miners were digging
The Vaal River is the only major river that we This impact site is one of the few “multi-ring the deepest mines in the world and the
know that flows right through an impact impact basins”, on Earth. These rings are foundation of the bustling metropolis we
crater. The river occupies channels in the ridges created by glacial erosion 300 million know today.
surface of the dome and flows through years ago. The others are only found in the
these cracks. solar system on Jupiter’s moon and our own Apart from literally sitting on a gold mine –
moon. the Vredefort Dome is rich in history. And
“It’s creating little canyons, it’s eating into the It’s one of the very few places on Earth
Vredefort Dome, and it is sliding sideways In 2005, 30% of the impact structure was where scientists travel across the globe to
across this hard granite layer that isn’t easy declared a world heritage site. see the Earth inside out.
to penetrate.’ He says. This was on the basis of its primarily
geological significance, which is the impact, One has to think about how different South
Along the banks and surrounding land but also the incredible age of the rocks that Africa might have been if the meteorite
lie rocks called shatter cones. These are are then exposed at the surface. So there’s a had landed elsewhere and nobody on
rocks which indicate enormous shock and rich archaeological heritage that is found in Earth knew there was gold waiting to be
pressure. the dome. discovered.

Surrounding hills showing crater rim Meteorite impact

Fourways Gardens • 29 • July 2024