Polygonal Dunes in Mars Skin
Polygons in this image taken by Hirise spacecraft orbiting Mars, 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. Image © NASA/JPL/University of Arizona
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.
Written by: Alfred McEwen
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