The Dunes of Herschel Crater (Saturated Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)

This image shows Dunes on the floor of Herschel Crater. The Steep Faces (a.k.a.: "Slip-Faces") of the Dunes are oriented downwind, in the direction of their motion. One feature of particular interest is the dune-free area downwind of the Crater towards the right side of the frame. Some sand has been trapped in the Crater, but the Crater prevents the Dunes from migrating directly downwind. Sand Dunes form naturally as a result of the transport of sand by the wind.
The Dunes in this image are somewhat crescent-shaped, but are being extended and distorted downwind and merging with nearby Dunes; this complex behavior is common in Dunefields on Earth.

In the left side of the image the sand lies in sheets rather than well-defined Dunes. At high resolution, the Dunes' Surface are covered in small Ripples and Scallops, also shaped by the wind.