(wrong string) ¿ ventifacted ?

From: j.divelbiss_at_att.net <j.divelbiss_at_meteoritecentral.com>
Date: Wed Jan 19 19:08:23 2005
Message-ID: <012020050008.7093.41EEF6660002D92200001BB521602810609C9C070D040A90070BD206_at_att.net>

Nick and others,

Challenging folks to provide further proof of extraordinary claims is a worth while effort.
I applaud your comments.

I've seen the evidence of significant ridge edge erosion of granite here in PA, and it is amazing to see the gouging affects of wind and rain.
The edges I've seen on this granite were more rounded than the sharp edged "holes" in the so-called iron meteorite on Mars.

My first reaction to Jeff's picture the other day was that the swiss cheese look of that rock sure looked similar to an iron meteorite on Earth. I probably still feel that way from just a visual point of view.

But then again my brain starts to wonder how did those hole/gouge-like features on that rock get there?
1. Normally we think of silicate burnout from irons during entry, or silicate fallout during erosion/weathering...but, did either of these things happen on Mars way back when?
2. Was there enough atmosphere on Mars during it's fall to cause significant ablation?
3. Can the energy of asteroidal collisions in space (or the collison w/Mars) cause the silicates to fallout...creating wholes, or reshape the iron to look like this, if ablation did not happen on Mars?
4. If it is erosion from wind, sand, etc....then I agree with Nick that significant proof is required to prove it isn't just another plain-old Mars rock (boy, is that an odd thing to say).

John



 
-------------- Original message from Nicholas Gessler <gessler_at_ucla.edu>: --------------


> Hi,
>
> Yes, "wind faceted" (wind and sand ablation) seems to be the key feature of
> relevance. If you look at photos of the alleged meteorite found on Mars,
> it contains quite a few facets. And the ridges between the facets are very
> sharp. I have seen hard quartzite and flint-like rocks on deserts with the
> same sharply delineated features. The ventifacted chondrites, on the other
> hand, do not show these facets or sharp delineations. Neither does the
> banded iron example or the other iron meteorite from Antarctica.
>
> As far as I know, these sharply delineated facets occur with wind and sand
> from a constant direction over a long period of time. And the material has
> to be hard and homogeneous. Consequently I wonder what a terrestrial iron
> meteorite would look like subjected to the same conditions? I have a new
> NWA iron that is otherwise round and smooth but clearly shows those lines
> but no facets. I'm sure it was attacked by water and by wind and sand, but
> how much by each I just don't know. I suppose even a solid hunk of
> non-meteoric iron subjected to the same conditions would answer the
> question. Unless the rock found on Mars is an ataxite, I would also expect
> that any attack (whether by acid or wind and sand) would reveal some
> evidence of Widmanstatten lines. I don't see any evidence of that in the
> Martian photograph.
>
> So as much as I think it's a keen idea to find a meteorite on Mars, I'm not
> convinced. "Extraordinary claims require extraordinary evidence." So my
> questions are:
> a) Why does the Martian rock show faceting? Does that support or detract
> from the claim that it is an iron meteorite?
> b) Exactly what analysis was done on Mars? I have only seen the most
> general reports for PR purposes. Can anyone point me to a more definitive
> report? Do we have access to the thermal heating and dissipation data, for
> instance? And what else?
>
> Cheers,
> Nick
>
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Received on Wed 19 Jan 2005 07:08:09 PM PST


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