This observation shows what we call “scalloped terrain,” that appears here to merge in a linear depression.
How do these scallops form? Possibly from the collapse of the terrain due to sublimation (when a solid transforms directly into a gaseous state) of subsurface ice. There is also a large number of rocks on the surface.
HiRISE resolution can help us examine the surface much more closely to see if there are any differences between the surrounding plains and the floor of these scalloped depressions.
Written by: HIRISE Science Team (audio by Tre Gibbs) (2 October 2013)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_033111_2300
Image: NASA/JPL/University of Arizona