Check out the stereo anaglyph of this scene . It shows dark sand dunes marching over the ridges created by an alluvial (water-deposited) fan in an impact crater. The subimage shows a small piece at full resolution.
These dunes may be active today, but we haven’t yet observed them at significantly different times to measure the movement. The dunes are moving from northwest (upper left) to southeast, with the steep slope facing downwind.
Written by: Alfred McEwen (29 February 2012)
This is a stereo pair with ESP_024913_1580 .
More info and image formats at http://hirise.lpl.arizona.edu/ESP_025625_1580
Image: NASA/JPL/University of Arizona