North Polar Gypsum Dunes in Olympia Undae – Unlike most of the sand dunes on Mars that are made of the volcanic rock basalt, these are made of a type of sulfate mineral called gypsum. (<a rel="nofollow" class="external text" href="http://www.uahirise.org/ESP_045501_2605">www.uahirise.org/ESP_045501_2605</a>)
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/71688597@N05">UAHiRISE (NASA)</a>
2016-07-13 15:25
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/uahirise-mars/28049782410/">ESP_045501_2605</a>