Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Martian rock arrangement not alien handiwork

09.01.2009
At first, figuring out how pebble-sized rocks organize themselves in evenly-spaced patterns in sand seemed simple and even intuitive. But once Andrew Leier, an assistant geoscience professor at the U of C, started observing, he discovered that the most commonly held notions did not apply.

And even more surprising, was that his findings revealed answers to NASA’s questions about sediment transport and surface processes on Mars. Those results are published in this month’s edition of Geology.

Leier first studied loose pebbles and rocks, also known as clasts, when he was looking at sand dunes in Wyoming and noticed that the clasts seemed to spread away from each other in an almost organized fashion. It turns out,NASA was examining similar patterns on the sandy surface of Mars. (See figure No. 1 below.)

NASA proposed that wind was moving these rocks around. But Leier, who co-authored the study with Jon Pelletier at the University of Arizona and James Steidtmann at the University of Wyoming, says that would be impossible. They also discovered that rather than being pushed backward by the breeze, clasts actually tend to move into the direction of prevailing winds.

“The wind is less effective at moving clasts on Mars because the atmosphere is less dense,” says Leier. “And for the wind to move the rocks downwind, it would have to be moving on the order of 8,000 kilometres an hour.”

Instead, the loose sand around clasts is removed by the wind, causing scour-pits to form in front of larger clasts. Eventually, the rocks fall forward (or laterally) into the scours and then, the process repeats. Behind the larger grains, the sand is protected from the wind erosion and so a "sand-shadow" develops. This shadow prevents the clasts from being pushed downwind and from bunching up with one another. (See figure No. 2 below.)

Leier and his team first came up with these results through observation but then took them to a wind tunnel at the University of Wyoming to test the theory. Here, a tightly grouped bunch of small pebbles were buried in sand and then the wind tunnel was activated and results photographed. Surprisingly, as the sand was eroded by the wind, the larger clasts moved into the wind and spread out from one another.

Numerical models, based on the physics of wind transport, were run to test these ideas. Just like what was observed in the wind tunnel, the numerical models predict that as the sand is blown away, the large pebbles will spread out from one another, and often move into the direction of the wind, regardless of their initial configuration.

So through a few simple feedbacks, the larger grains on a windy, sandy surface will inherently spread out and organize (or dis-organize) themselves.

“What I find most interesting about this is that something as seemingly mundane as the distribution of rocks on a sandy, wind-blown surface can actually be used to tell us a lot about how wind-related processes operate on a place as familiar as the Earth and as alien as Mars,” says Leier. “It’s chaotic and simple at the same time.”

Leier’s article Wind-driven reorganization of coarse clasts on the surface of Mars is published in the January 2009 edition of Geology. It can be viewed online at www.gsajournals.org/.

Leanne Yohemas | EurekAlert!
Further information:
http://www.ucalgary.ca/news/utoday/jan7-09/martianrock
http://www.ucalgary.ca

More articles from Earth Sciences:

nachricht Heidelberg Researchers Study Unique Underwater Stalactites
24.11.2017 | Universität Heidelberg

nachricht Lightning, with a chance of antimatter
24.11.2017 | Kyoto University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New proton record: Researchers measure magnetic moment with greatest possible precision

High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons

The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

IceCube experiment finds Earth can block high-energy particles from nuclear reactions

24.11.2017 | Physics and Astronomy

A 'half-hearted' solution to one-sided heart failure

24.11.2017 | Health and Medicine

Heidelberg Researchers Study Unique Underwater Stalactites

24.11.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>