Oh here's a good one. This is probably my all time favourite geology whoopee thing.
Did you know
that the world's biggest diamond deposit is found in a hemispherical shell that is one mile thick and has an outside radius of 8 1/2 miles?
Reason: it was formed in a fraction of a second directly under ground zero of an asteroid impact. No shit.
Outside an 8 1/2 mile radius the pressures weren't high enough to form diamond.
Inside a 7 1/2 mile radius, pressures were high enough to destroy diamonds by regraphitization, conversion to SiC, melting, or vaporization.
Ladies and gentlemen, meet
Popigai Crater.
Devious, treacherous, murderous, neanderthal, sub-human of the West.