This image shows pole-facing gullies in a southern hemisphere crater. Gullies are young features that are widely thought to form from fluvial processes involving liquid water. These particular gullies have very fine channels, including some that intersect and overlap. This is evidence that multiple flow events occurred within the gullies.
The wavy, arcuate ridges at the bottom of the slope may have formed by gravity moving ice-rich material off the crater wall. The pitted texture of the crater floor suggests that volatiles (ices that easily turn into gas) escaped from the subsurface, causing the surrounding material to collapse and form small pits.
Written by: Kelly Kolb (8 June 2008)
More info and image formats at http://hirise.lpl.arizona.edu/PSP_006760_1370
Image: NASA/JPL/University of Arizona