Possible pingos in Mare Acidalium, as seen by hirise under HiWish program
Jim Secosky modified NASA image.  NASA/JPL/ University of Arizona
2016-03-04
<a rel="nofollow" class="external free" href="http://hirise.lpl.arizona.edu/ESP_044322_2215">http://hirise.lpl.arizona.edu/ESP_044322_2215</a>