Wikipedia:Reference desk/Archives/Science/2019 May 28

Science desk
< May 27	<< Apr | May | Jun >>	May 29 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

May 28

Mars and erosion

Please would someone explain to me why my hypothesis is wrong. It occurs to me that the water erosion seen on Mars could just as easily have been the result of erosion by sand. If the sand is of a sufficiently small particle make up, much like talcum powder or finer, then surely in large quantities this would start to act much like a liquid thereby the valleys and canyons cut could simply be the result of sand erosion as blown by high speed winds. I would pose the same question in opposition to the theory that the Sphinx in Egypt is too eroded by water rather than wind. Surely this could be the result of fine grained sand acting much like a liquid. I believe that in both cases this would be a much easier and simpler explanation than water and would be in inline with occam's razor Thanks Anton 81.131.40.58 (talk) 13:16, 28 May 2019 (UTC)

Does wind produce features that look like riverbeds? ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:49, 28 May 2019 (UTC)

Evidence for the action of water on Mars comes not only from the observed landforms, but from the rocks studied by the rovers. The kind of sedimentary rocks produced by erosion, transport and deposition by wind are mostly distinguishable from those involving water. Depositional environments are identified from lithology, sedimentary structures and association of various rock types. Geologists (particularly sedimentologists), make this sort of distinction routinely. Mikenorton (talk) 14:26, 28 May 2019 (UTC)

(EC) Wind erosion definitely played a part in shaping the Mars we see today and I don't think any sources dispute that see e.g. [1] from the ESA and this [2] from Astrobiology Magazine, these [3] [4] from the Lunar and Planetary Institute of the Universities Space Research Association. This news story from Science [5] primarily discussing this [6] Nature Geoscience paper discusses the complexities of differentiating the relative contributions of erosion caused by wind and by water on earth. And these news story from the Washington Post [7] and Phys.org [8] discusses these studies [9] [10] relating to the debate over whether the observed modern day phenomenon of recurring slope lineae are primarily due to liquid brines or dry granular flows. Note that you may also notice that none of the sources I provided (that I noticed) dispute the contribution of liquid water flows in the past. Nil Einne (talk) 14:32, 28 May 2019 (UTC)

Mars ocean hypothesis is worth reading. There is a large amount of independent evidence for liquid water on Mars in its past. There is still debate over the amount of water, and its contribution to shaping the planet compared to other factors, including wind erosion. Note that Mars's atmosphere is much less dense than Earth's, because Mars is less massive, and this of course reduces the force of the wind. --47.146.63.87 (talk) 22:53, 28 May 2019 (UTC)

This NASA writeup implies why the OP's scenario is unlikely,[11] due to the much-thinner atmosphere of Mars and its top wind speed of only 60 MPH. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:30, 29 May 2019 (UTC)