Sand dunes in Valles Marineris can be impressive in size, with steep slopes that seem to climb and descend.
An enhanced-color cutout shows some of these on the slopes of Nectaris Montes within Coprates Chasma.
The brighter bedforms are inactive while the bigger dunes move over the landscape, burying and exhuming the surface.
NASA/JPL/University of Arizona (262 km above the surface, less than 1 km across.)
