3 ms·
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
by jdonaldson 8y ago
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.
- jacquesm 8y agoTwo billion years is a lot of time to wipe out useful clues.
- jdonaldson 8y agoI 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?
- jacquesm 8y ago> 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.
- jdonaldson 8y agoHere'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.