Sand, wind, and dust

A piece of Mars: This is what dunes look like in the deepest part of Mars, where the air is full of bright dust that constantly settles out onto everything. The wind helps to clear off the sand dunes (blue in this image) in two ways: one is by dust devils that leave crooked tracks like drunk vacuum cleaners, and the other is by sand avalanches down steep dune slip faces (HiRISE ESP_025278_1345).