[meteorite-list] A point of contention/question

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Thu, 9 Oct 2008 04:39:26 -0700 (MST)
Message-ID: <49392.71.226.60.25.1223552366.squirrel_at_timber.lpl.arizona.edu>

Hello Pete:

Yes, the Earth shoulc look like Mars or Mercury (or the Moon for that
matter).

However, you are on the right track.

I am sure that Sterling will respond with more detailed comments, but here
are a few of the things that affect what we see:

1. Atmosphere: as in the case of the recent impact on Earth (2008 TC3)
"small" things do not make it to the surface.

2. Atmosphere (wind and water): weathering will wear away, fill in
craters. Just look at what it does to mountain ranges over millions of
years.

3. Plate tectonics: very few old surfaces on the Earth. Lava could cover
the craters, plates move and land goes away or is messed up when plates
meet, etc.

4. An object could land in the water, never to be "seen."

I am sure there are other things, but this is a good start on why the
Earth does not look like the other terrestrial planets or the Moon (Venus
being much closer to Earth thanks to its atmosphere and having been
resurfaced).

Larry


On Wed, October 8, 2008 9:06 pm, Pete Shugar wrote:
> On the one hand, there are rather stunning photos of a
> very cratered Mercury and on the other side of us a very pock-marked Mars.
> Both look like you couldn't even walk
> a hundred feet in any direction without stepping in another crater.
>
> 1
> If they are so cratered from "meteorites" (was there an atmosphere?)
> that they are everywhere, Would not the earth look the same- excluding the
> drifting contental plates? I know there is a meteorite for every wide spot
> in the road in West Texas. (I'm trying to collect every one of them.) 2
> It would seem to me that almost anywhere that you wanted to go,
> you could conceivably find a meteorite. 3
> Is the movement of the plates what keeps the earth's landscape
> from looking like Mars or Mercury? 4
> All the craters on earth are huge (the smallest that I know is Odessa
> at a mere 550 feet). Actually there are 5 craters, making it a rather
> complex system with the smallest at just over 22 feet, but it is a very
> young crater at ~50,000 years old about as old as is Canyon Diablo. This
> excludes Carancus as I'm not convinced it is a true crater. Is there any
> evidence of micro sized craters? Maybe something on the order of only 50
> feet to maybe 100 feet across that is truly old? Pete
>
>
>
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Received on Thu 09 Oct 2008 07:39:26 AM PDT