Last updated on April 16, 2014 at 13:58 EDT
Concentric Crater Fill
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Concentric Crater Fill

October 12, 2009
The bizarre patterns on the floor of this crater in Nilosyrtis Mensae defy an easy explanation. At 34 degrees north latitude, this location hardly qualifies as 'Arctic' yet it is likely that some form of periglacial process possibly combined with the vaporization of ground ice is responsible for this intriguing landscape.