[meteorite-list] Rock and roll on Mars

From: Rob McCafferty <rob_mccafferty_at_meteoritecentral.com>
Date: Thu, 15 Jan 2009 16:45:21 -0800 (PST)
Message-ID: <833719.29995.qm_at_web55203.mail.re4.yahoo.com>

This is a wonderful explanation. It is incredibly simple but almost certainly right.

I have seen a similar effect on the windswept beaches of the Western Isles. OK, we're only talkin about a few feet but you get a similar effect (before the tide comes in and wipes it clean).

Often I have seen trains of tiny particles behind a stone on the beach when the wind blows strongly but consistently. Pits do form in front of obstacles and while I've never seen a rock move forward (that's the only bit I have a problem with) into the wind, you do see trains behind them.

While most of us would easily recognise Universal Gravitation, General Relativity and Quantum Electro Dynamics as genius, the minds that think of these things are far in advance of us "everyday" mortals. The everyday bores the Einsteins, Newtons and Yukawa's.
It takes a special type of genius to spot the everyday stuff like this. The sort of thing we think we could have come up with if only we were a little smarter.
Whether this turns out to be right or wrong as an explanation, I take my hat off (and I really do wear a hat, it's an Indiana Jones type one..how sad) to the proponent of this theory.

Rob McC


--- On Thu, 1/15/09, ensoramanda at ntlworld.com <ensoramanda at ntlworld.com> wrote:

> From: ensoramanda at ntlworld.com <ensoramanda at ntlworld.com>
> Subject: Re: [meteorite-list] Rock and roll on Mars
> To: Meteorite-list at meteoritecentral.com, cynapse at charter.net
> Date: Thursday, January 15, 2009, 12:34 PM
> Hi Darren/All,
>
> Over the years I have seen many photographs of desert
> meteorite finds where the meteorite looked almost as if it
> had hit and fractured on impact and only spreading around a
> short way....but this mechanism would explain that much
> better with the meteorite weathering and fracturing over
> time and not on impact and then slowly spreading out over
> time into an even pattern.
>
> Graham Ensor, UK.
>
>
> ---- Darren Garrison <cynapse at charter.net> wrote:
> > http://www.foxnews.com/story/0,2933,479873,00.html
> >
> > Strange Rock Formations on Mars Explained
> >
> > Wednesday, January 14, 2009
> >
> > Rocks on Mars are in some areas scattered in a
> strangely uniform fashion,
> > puzzling scientists for years. Now they've figured
> it out.
> >
> > Researchers had thought the rocks were picked up and
> carried downwind by extreme
> > high-speed winds thought to occur on Mars in the past.
> >
> > Although Mars is a windy planet, its atmosphere is
> very thin, so it would be
> > difficult for the wind to carry the small rocks, which
> range in size from a
> > quarter to a softball, said Jon Pelletier, a
> geoscientist at the University of
> > Arizona in Tucson.
> >
> > Pelletier and his colleagues now think the rocks are
> constantly on the move,
> > rolling into the wind, not away from it, and creating
> a natural feedback system
> > that results in their tidy arrangement.
> >
> > Rock-n-roll
> >
> > Here's what they think happens: Wind removes loose
> sand in front of the rocks,
> > creating pits there and depositing that sand behind
> the rocks, creating mounds.
> > The rocks then roll forward into the pits, moving into
> the wind. As long as the
> > wind continues to blow, the process is repeated and
> the rocks move forward.
> >
> > The rocks protect the tiny sand mounds from wind
> erosion. Those piles of sand,
> > in turn, keep the rocks from being pushed downwind and
> from bunching up with one
> > another.
> >
> > "You get this happening five, 10, 20 times then
> you start to really move these
> > things around," Pelletier said. "They can
> move many times their diameter."
> >
> > The process is nearly the same with a cluster of
> rocks. However, with a cluster
> > of rocks, those in the front of the group shield their
> counterparts in the
> > middle or on the edges from the wind, Pelletier said.
> >
> > Because the middle and outer rocks are not directly
> hit by the wind, the wind
> > creates pits to the sides of those rocks. And so,
> instead of rolling forward,
> > the rocks roll to the side, not directly into the
> wind, and the cluster begins
> > to spread out.
> >
> > The research is published in the January issue of the
> journal Geology.
> >
> > Lots of evidence
> >
> > Several pieces of evidence have come together to
> support this idea of how rocks
> > are organized along some areas of the Martian surface.
> >
> > For instance, when study team member Andrew Leier of
> the University of Calgary
> > in Canada was a graduate student at UA, he told
> Pelletier about an experiment on
> > the upwind migration of rocks that his thesis advisor
> James Steidtmann of the
> > University of Wyoming had conducted.
> >
> > Steidtmann used a wind tunnel to see how pebbles on
> sand moved in the wind,
> > revealing the rocks moved upwind and that over time, a
> regular pattern emerged.
> >
> > Some time later, while attending a lecture that showed
> pictures of uniformly
> > organized rocks on Mars, Pelletier recalled his
> conversations with Leier, and it
> > all came together.
> >
> > Meanwhile, Leier had noticed a similar phenomenon when
> observing sand dunes in
> > Wyoming. Basically, loose pebbles and rocks there
> seemed to spread away from
> > each other in an almost organized fashion similar to
> what is seen on the sandy
> > surface of Mars.
> >
> > In the recent study, Pelletier tested out the idea
> with three computer models,
> > including models of air flow, sand erosion and
> deposition, and rock movement.
> >
> > He compared the model results with the distances
> between each rock and its
> > nearest neighbor in Mars images taken by the Mars
> Exploration Rover, Spirit. The
> > patterns of the Martian rocks matched what the model
> predicted.
> >
> > Pelletier plans to apply the same numerical models to
> larger features on Mars
> > such as sand dunes and wind-sculpted valleys and
> ridges called "yardangs."
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Received on Thu 15 Jan 2009 07:45:21 PM PST