This subimage, about 2.5 kilometers across, shows the south polar layered deposits exposed in a scarp illuminated from the lower right.

This image was taken in the southern spring (2007), when the surface was completely covered by carbon dioxide frost. Therefore, most of the brightness variations in this scene are caused by topography.

The polar layered deposits are broken into blocks by fractures in two directions. Neither set of fractures is parallel to the current scarp face, suggesting that they were not formed as the scarp was eroded, but instead are due to pre-existing weaknesses in the polar layered deposits.

The four craters at lower left appear to have formed at the same time by an impactor that broke up as it entered the Martian atmosphere. The presence of many craters such as these on the south polar layered deposits indicates that they are not as young as the north polar layered deposits, which have very few craters on them.

Written by: Ken Herkenhoff   (15 September 2010)

More info and image formats at http://hirise.lpl.arizona.edu/PSP_002882_0940

Image: NASA/JPL/University of Arizona