Pits in Hale Crater Ejecta

The pits visible in this image from NASA Mars Reconnaissance Orbiter arent impact craters. The material they are embedded into is ejecta stuff thrown out of an impact crater when it forms from a large crater called Hale not seen in this image.

Substances called "volatiles" -- which can explode as gases when they're quickly warmed by the immense heat of an impact-exploded out of the ejecta and caused these pits. Unrelated sand dunes near the top of the image have since blown over portions of the pits.

http://photojournal.jpl.nasa.gov/catalog/PIA19289