This observation shows gullies in a Southern hemisphere crater, whose floor has large mounds of material that are likely slump blocks that fell off the crater walls during a late stage of formation. There are also a large number of dunes of different sizes and facing different directions on the crater floor.

The gullies visible in this image formed over a period of time. The majority of them have experienced modification since they formed. This can be seen in the form of polygonal fractures on their walls, dunes or ripples on their channel floors, and rocks and material fallen from their walls ( see subimage ). Some of the gullies facing east were active more recently. They do not have polygonal fractures or they have fractures that are less well-developed. A narrow, primarily unmodified channel is also visible.

It is unknown over what period of time gullies formed in individual settings and globally. It is possible that gully formation continues today.
Written by: Kelly Kolb   (17 November 2010)

This is a stereo pair with PSP_003517_1395 .

More info and image formats at http://hirise.lpl.arizona.edu/PSP_002884_1395

Image: NASA/JPL/University of Arizona