File:Proctor Crater Dune Field.jpg
Summary
This observation shows the edge of a dark dune field on the floor of Proctor Crater, a 150-kilometre diameter crater in the Southern highlands of Mars.
The dark dunes are composed of basaltic <a href="//commons.wikimedia.org/wiki/Sand" title="Sand">sand</a> that has collected on the bottom of the crater. Dark dune slip faces (the steeper sides of the dunes) are located on the east side of the dunes and are believed to have formed in response to <a href="//commons.wikimedia.org/wiki/Fall" class="mw-redirect" title="Fall">fall</a> and <a href="//commons.wikimedia.org/wiki/Winter" title="Winter">winter</a> westerly winds caused by geostrophic forces (winds balanced by Coriolis and <a href="//commons.wikimedia.org/wiki/Category:Pressure" title="Category:Pressure">pressure</a> <a href="//commons.wikimedia.org/wiki/Category:Gradient" title="Category:Gradient">gradient</a> forces). Superimposed on their surface are smaller secondary dunes that are commonly seen on terrestrial dunes of this size.
Many smaller and brighter <a href="//commons.wikimedia.org/wiki/Bed" class="mw-redirect" title="Bed">bed</a> forms, most likely small dunes or granule ripples, cover the substrate between the larger dark dunes as well as most of the floor of Proctor Crater. The dark dunes overlie the small bright bed-forms indicating that they formed more recently. In several areas, however, the dark dunes appear to influence the orientation of the small bright dunes, possibly by <a href="//commons.wikimedia.org/wiki/Wind" title="Wind">wind</a> flowing around the larger ones, suggesting that both dark and bright bed-forms are coeval. The dunes in Proctor Crater may be active today, moving in response to Martian winds.
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File history
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 18:11, 13 January 2017 | | 2,560 × 1,920 (4.34 MB) | 127.0.0.1 (talk) | This observation shows the edge of a dark dune field on the floor of Proctor Crater, a 150-kilometre diameter crater in the Southern highlands of Mars. <p>The dark dunes are composed of basaltic <a href="//commons.wikimedia.org/wiki/Sand" title="Sand">sand</a> that has collected on the bottom of the crater. Dark dune slip faces (the steeper sides of the dunes) are located on the east side of the dunes and are believed to have formed in response to <a href="//commons.wikimedia.org/wiki/Fall" class="mw-redirect" title="Fall">fall</a> and <a href="//commons.wikimedia.org/wiki/Winter" title="Winter">winter</a> westerly winds caused by geostrophic forces (winds balanced by Coriolis and <a href="//commons.wikimedia.org/wiki/Category:Pressure" title="Category:Pressure">pressure</a> <a href="//commons.wikimedia.org/wiki/Category:Gradient" title="Category:Gradient">gradient</a> forces). Superimposed on their surface are smaller secondary dunes that are commonly seen on terrestrial dunes of this size. </p> Many smaller and brighter <a href="//commons.wikimedia.org/wiki/Bed" class="mw-redirect" title="Bed">bed</a> forms, most likely small dunes or granule ripples, cover the substrate between the larger dark dunes as well as most of the floor of Proctor Crater. The dark dunes overlie the small bright bed-forms indicating that they formed more recently. In several areas, however, the dark dunes appear to influence the orientation of the small bright dunes, possibly by <a href="//commons.wikimedia.org/wiki/Wind" title="Wind">wind</a> flowing around the larger ones, suggesting that both dark and bright bed-forms are coeval. The dunes in Proctor Crater may be active today, moving in response to Martian winds. |
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