[meteorite-list] "Boulders" on Mars

From: Kelly Webb <kelly_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:11 2004
Message-ID: <3A96144F.237AA033_at_bhil.com>

STUARTATK_at_aol.com wrote:

> All,
> When I read this story...
>
> ttp://planetary.org/html/news/articlearchive/headlines/2001/marsmystery.html
>
> ... and look at this picture...
>
> ttp://planetary.org/html/news/articlearchive/headlines/2001/Images/big_boulders.gif
>
> .... why do the words "strewn field" spring to mind?
> I know, probably not, but wouldn't it be great to go take a look? ;-)
>
> Stu

Stu,
    I will bring oxygen, food, and beer, if you will provide
transportation!
    I notice that the medium size boulders that arc from the top center
down to the left and the linear scattering of small boulders that
continue down and to the right seem neatly arranged on the very boundary
of the debris apron of that rather degraded "splosh" crater
    The linear scatter is sinuous but there's no evidence a channel. The
"Central Cluster" contains all the largest pieces and they do look as if
they were fractured and dropped there. The article mentions the slope of
the area but doesn't say what direction the strike of the slope is. I
assume downslope is from lower right to upper left from the Central
Cluster and radially from the crater.
    To me, it looks like the boulders are glacial erratics, the small
boulders carried along an ice channel until it slowly melted out from
under them, the medium boulders carried down to the edge of the glacier
at the debris apron, while the large boulders were left in place where
they were fractured. I say slowly melted since there is no evidence of
water outflow channels from a rapid melt. I wonder what the Martian
lattitude and longitude of this spot is and the scale of the image? I
wonder what's in the next frame to the east (right) of this one?
    The fact that there doesn't seem to be any local source for the
boulders is "normal" for glacial erratics. Ice can carry huge loads
incredible distances.
    Of course, I could be biased in seeing these as glacial erratics. I
live about a quarter mile from from the Mississippi River and in a
valley about five blocks away there's a chunk of Canada the size of a
compact car sitting there surrounded by hundreds of miles of nothing but
limestone and it's saying to itself, "How the hell did I get here?"
    A strewn field would be sorted by size from one end of the elipse to
the other, normally. Only one way to find out for sure.
    Remember, I bring the oxygen, food, and beer...

Kelly Webb
Received on Fri 23 Feb 2001 02:42:07 AM PST