
Vredefort Crater, the world’s oldest and largest known impact structure - zerealshadowban
https://earthobservatory.nasa.gov/images/92689/vredefort-crater
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rexfuzzle
I grew up in the town called Parys on the map in the article. Besides creating
some lovely hikes and river rafting there are also some very interesting rock
phenomena that can only be seen in this area in the whole world.

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sacrosurf
Can you share some examples? I wonder if my own searching will reveal many.

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baruchthescribe
Not from Parys but used to be a regular visitor: one example is streaks of
obsidian in the rocks from the explosion which I believe is unique.

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jacquesm
I read that and thought that it would be an excellent spot to prospect for
gold, then it turns out that this is already the source of 1/3rd of all the
gold mined on earth. Oh well, I'll have to wait for another good idea I guess.

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scrappyjoe
Fun fact. The Vredefort Impact Area is roughly overlaid by a larger geological
feature called the Bushveld Igneous Complex, which is from a totally unrelated
geological event but resulted in this area having 60% of all the platinum and
palladium in the world. So South Africa is stupendously geologically lucky
twice over.

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mrob
If you're interested in impact craters, I recommend the book "Traces of
Catastrophe" by Bevan M. French. You can read it here:

[https://www.lpi.usra.edu/publications/books/CB-954/CB-954.in...](https://www.lpi.usra.edu/publications/books/CB-954/CB-954.intro.html)

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adrianmonk
> _impact was so strong that a 25-kilometer section of Earth’s crust was
> turned on end_

This makes it sound like there was a 25km tall piece of crust sticking up into
the air, at least for a moment. Is that really what happened or did I
interpret "on end" wrong?

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Someone
I think you’re interpreting the “25km” part incorrectly. It could be a 25km
long, x m wide stretch that’s turned to form a 25km long, x m high ‘wall’.

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adrianmonk
At this point, I'm purely splitting hairs, but I would probably have said
"turned on its side" or some other variation of "side" instead, because "end"
means something different to me.

But obviously what you're saying makes way more sense physically, so that has
to be what it is.

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Freestyler_3
I wonder if the asteroid brought any rare materials.

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jdonaldson
Kinda disappointed nobody could figure out how big this was originally. Yes,
we've lost a couple of soil layers to erosion, and yes the bottom has filled a
bit with newer rock formations.

Still, you'd have to think we could estimate how big an object would need to
be to carve out that much bedrock, assuming a given amount of topsoil.

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jacquesm
Two billion years is a lot of time to wipe out useful clues.

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jdonaldson
I know, but the bedrock is unlikely to have changed that much. You could make
a ballpark estimate on the mass and energy needed for that alone.

Still, I understand the top layer composition matters a lot in terms of how it
could absorb an impact. Was it full of water? Earth? Sand?

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jacquesm
> but the bedrock is unlikely to have changed that much.

We're talking about the time before the continents had formed, the scale we
are looking at here is non-intuitive.

At that level of impact energy everything starts to behave like a fluid, even
planet earth, so whether or not the top layer composition was water, soil,
sand or rock is not that important. What's amazing is that there are traces
left that much later, even more how large those features are. That's a
testament to how enormous the impact must have been.

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jdonaldson
Here's the only reliable looking page I could fine :
[http://www.hartrao.ac.za/other/vredefort/vredefort.html](http://www.hartrao.ac.za/other/vredefort/vredefort.html)

Original impact crater estimated to be 300Km in diameter. They think 70 cubic
KM of soil was vaporized. For comparison's sake Mt St Helens explosion
vaporized 1 cubic KM of soil and rock. Chixculub crater is 150Km in diameter,
much much newer, but completely buried.

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aaaaaaaaaab
2 billion years old? I wonder if it had any impact on the Huronian glaciation
which occured roughly at the same time...

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liftbigweights
That's amazing considering that pangea was created 270 million years ago and
broke apart 200 million years ago.

