Page 33 - Intra Muros October Issue 2025

ESTATE NEWS

Estimates and assumptions of the
asteroid(s) size, the speed of entry
and geomorphological impact
- Puts the size of the rock at between
22km and 25km in diameter.
- More conservative estimates are 8km to
15km.
- Some even mention more than one
“rock/asteroid” following each other
closely.
- The chondrite asteroid, comprising
silica, water and some iron or metallic
meteorite, was speeding at between 70
000km and 100 000km per hour.
- The energy release amounted to millions
or even billions of Hiroshima-sized
nuclear bombs.
- At temperatures of about 5 000 degrees
Celsius.
- The asteroid(s) blasted right through the
younger Karoo, Ecca and Dwyka strata,
into the older Transvaal strata of the
Witwatersrand Craton.
- The explosions from vapourised rock
pushed the floor down and lifted the
roof of the chamber until it split in
a 146km ring, releasing a 1 000km
One can clearly see the 20km-wide Timeline: mushroom-shaped superheated fireball
surrounding collar of the nearly - 5 billion years ago (bya): Sun forms of incandescent gas which lasted for
vertical upturned upper crust layers more than two hours.
(Witwatersrand Basin sediments), the - 4.3 bya: Earth and Moon form - Energy released was 180 billion times
result of the immense impact. - 3.5 bya: Prokaryotes (single-celled that of both the Hiroshima and Nagasaki
organisms) appear atom bombs.
The full 284km impact diameter of the - 3 bya: Wits Basin forms – seven - Created a cavity with a current depth of
meteorite hitting Earth here in the heart hardened and crystalised layers, 15km.
of our amazing country comprises “the including gold powder and gold - It is calculated that the cavity created
largest known impact site on Earth”. conglomerates, were deposited into could have been as deep as 29km; the
Its possible influence stretches up into a large inland lake and formed into rest eroded away over millennia.
Zimbabwe! rock strata - ‘Reading’ shattercones in the area, it was
- 2 023 bya: Vredefort Impact estimated that the cavity diameter could
The Vredefort Impact and gold - 65 million years ago (mya): Extinction be 120km to 140km.
Most Johannesburgers have no idea - With new methods available today, these
that they are living on the edge of a of dinosaurs measurements put the diameter floor-
massive meteorite crater, with the gold - 3 mya: Origins of human species level of the rebound at 95km and the final
under their feet being the result of this - 1.5 mya: Stone Age rim at 248km, possibly extending into
impact. In popular geomorphology this - 250 000 years ago (ya): Tswaing Zimbabwe. New scientific developments
is the “third ring”, a remainder of the impact = crater north of Pretoria and ongoing research is slowly but surely
outer rock formations of the crater.
- 150 000 ya: Modern humans creating a more precise picture.
- In the process of the asteroid hitting
- 85 000 – 70 000 ya: Mathematics
It is believed that the asteroid hit two where it did, the impact tilted the ‘old’
billion years ago (nearly half the age of - 4 600 ya: Pyramids Witwatersrand Super Group rock strata
our Earth) and completely vaporised - Thousands of years ago: Rock art containing the world’s largest deposits
itself in the biggest energy release of - 350 ya: Industrial Age of gold, pushing it underground to be
which we have any record here on - 132 ya: Gold Rush (1880s) preserved instead of eroded away in
Earth. time.

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