Crater Dunes

This VIS image displays sand dunes within an unnamed creater in Noachis Terra. These dunes are composed of basaltic sand that has collected in the bottom of the crater. The topographic depression of the crater forms a sand trap that prevents the sand from escaping. Dune fields are common in the bottoms of craters on Mars and appear as dark splotches that often lean up against the downwind walls of the craters. Dunes are useful for studying both the geology and meteorology of Mars.