Windy Mars

Though Mars' atmosphere is extremely thin, its winds can be quite strong.  The winds, in fact, have played, and continue to play, a role in the shaping of the planet's surface.

Researchers working with images taken by the Mars Reconnaissance Orbiter over several years have noted surface changes.  Some have been "sand avalanches" in the sand sea of the northern polar regions.  Some scientists think the best explanation for such avalanches is strong wind beginning the movement down the sandy slope.  Researchers have also noted sand dunes drifting across the surface, driven by the winds.

Mars is still, therefore, a dynamic world.  If it is still geologically active, there is a chance it could be biologically active to this day, as well.