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Re: impacts are cool!

Jonathon Woolf wrote:
> Michael wrote:
> <snip>
> > The size of the crater suggests at the very least 180km and more likely
> > 230-300km in diameter.
> The crater is this big?  

The crater is this size.  The most likely scenario is a comet 10-17km in
size.  An asteroid would be  smaller and a stoney meteor somewhere in

> Overkill.  Complete, total, absolute overkill.  An impact with
> consequences like that would have killed every green thing on the planet
> and left it completely sterile, except perhaps for hydrothermal vent
> communities a kilometer below the ocean surface.  The Asteroid Doomsday
> scenario is illogical, because it is completely contradicted by the
> evidence.  Whatever happened at the K-T border caused widespread havoc
> among both land and aquatic ecosystems, but _some_ life _did_ survive.
> Don't forget that.  Something Did Survive.  IMHO, that simple fact
> conclusively disproves Asteroid Doomsday.

This is not logical thinking IMO.  The crater is there.  It takes an X
sized object of certain mass and speed to create it and that releases X
amount of energy.  I will say that at its lower limit size of 170-180km,
it would not be a biosphere threatening event in the opinion of most of
the people studying this thing.  A 300km crater would release enough
energy to cause worldwide havoc.  It still would not sterilize the

That brings up an interesting question of what would be the minimum
size, composition and speed of an object to cause earth to lose its seas
and/or atmosphere.
       Michael Teuton

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