<p>Complex Dunes in Kaiser Crater — Dunes form when loose sand-sized materials are transported and deposited by a moving fluid, in this case wind. The present atmosphere of Mars is more than 100 times thinner than that of Earth. As a consequence, it is much more difficult for wind to move sand particles on Mars than it is on Earth. The dunes at Kaiser Crater must have formed under winds much stronger than those responsible for building similar dunes on our planet. 
</p>
NASA/JPL/University of Arizona (251 km above the surface) <a rel="nofollow" class="external text" href="https://www.uahirise.org/PSP_006609_1330">www.uahirise.org/PSP_006609_1330</a>
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/71688597@N05">UAHiRISE (NASA)</a>
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/uahirise-mars/39172151522/">PSP_006609_1330</a>