HiRISE: Craters within craters

Sandwiched between a crater nearly 4 kilometer across and a much larger and older crater over 15-kilometers in diameter is this small impact crater with light-toned material exposed in its ejecta. Because the material is still brighter than the surrounding surface, darker dust settling out of the atmosphere has not had time to cover it up, so the crater is fairly recent. Of course, “recent” could mean on the order of thousands of years or older. This small crater is also fairly shallow and smooth in its interior…. [More at link]