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.
Photo credit: NASA/JPL/University of Arizona
Note: This location is north of Protonilus Mensae in Vastitas Borealis. It is due east, at some distance, of Lyot Crater.