Polygons are of great interest because they often indicate the presence of shallow ice or of desiccation such as in a mud flat. However, Nature sometimes seems too clever for us.
Polygons form by the intersecting ridges of sand dunes
. If this deposit were to become indurated and eroded, we might not be able to tell that they originated as wind-blown dunes, and interpret the polygons as evidence for a dried-up lake, for example. Dunes often accumulate in the bottoms on craters, also a good setting for a (temporary) lake.
The illumination is coming from the upper left, so the bluish ridges are high-standing. ID
: 18 March 2013 altitude
: 252 km
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