Sand dunes on Mars take many shapes and forms. They can develop in all sorts of areas, including valleys and crater floors.
Large dunes on the floor of the 300-kilometer (180-mile) wide Herschel Impact Basin. Grooves along the dunes, apparently carved by wind, suggest that the dunes have become hardened and stationary.
Mars Global Surveyor, MOC NASA/JPL/Malin Space Science Systems image
A northern plain is dotted with small barchan (crescent-shaped) dunes. The horns of the dunes point downwind. Barchan dunes are common on Earth, where they form on level areas with constant winds and limited sources of sand.
Mars Global Surveyor, MOC NASA/JPL/Malin Space Science Systems image
A dune field in the lowest part of Victoria Crater, which measures about 800 meters (half a mile) across.
Mars Global Surveyor, MOC NASA/JPL/University of Arizona image
A dune field in Wirtz Crater, a large impact crater in the southern highlands. The wind shaping these dunes blows from the southwest (bottom left).
NASA/JPL/Malin Space Science Systems image
Delicately beautiful dune patterns grace the floor of small Endurance Crater. The curving ridges at the bottom are less than a meter high.
NASA/JPL/Cornell false color image
