Sand dune populations on Mars can vary widely with respect to morphology, relief, and activity. One of the most striking examples occurs with the many dune fields of the high Southern latitudes.
When we venture south of -60 degrees latitude, we see increasing signs of dune degradation, with subdued dune brinks and broad sandy aprons, rather than sharp, dune crests and distinct boundaries. Dunes this far south are also very modest in height, often consisting solely of flat sand sheets. Additionally, global monitoring campaigns are revealing a noticeable lack of changes in these bedform positions, whereas many dunes and ripples to the north are migrating across the surface. [More at link]