This image shows portions of the northwest and southwest rims of a Northern hemisphere crater. The northwest rim has gullies, features frequently proposed to be carved by fluvial processes or debris flows.
The dark material on the crater floor is dust; some if it has been moved by dust devils to form the dark streaks visible here.
The scene has two main textures: smooth and pitted. The smooth, mantling material is thought to be ice-rich. The pitted regions are thought to mark locations where the subsurface ice has been removed by sublimation, when ices convert directly to gas.
Written by: Kelly Kolb (28 January 2009)
More info and image formats at http://hirise.lpl.arizona.edu/PSP_010679_2205
Image: NASA/JPL/University of Arizona