Layers and Dark Dunes

Much of Mars’ surface is covered by fine-grained materials that hide the bedrock, but in this scene from NASA Mars Reconnaissance Orbiter, the bedrock is well exposed except where covered by sand dunes.

The original image scale is 26.7 centimeters (10.5 inches) per pixel (with 1 x 1 binning); objects on the order of 80 centimeters (31.5 inches) across are resolved.] North is up.

http://photojournal.jpl.nasa.gov/catalog/PIA21463