Dust Devil Tracks in Gusev Crater (Extremely Enhanced Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)

Gusev Crater is decorated by tracks made by Dust Devils that have been observed by the Mars Exploration Rover Spirit, Mars Orbiter Camera (MOC), and HiRISE images.
Dust Devils are of interest because they may clean the Solar Panels that provide power to Spirit, and are partially responsible for dust transportation on the surface of Mars.

Dust Devils are actually giant convective vortices that form as a result of atmospheric vertical instability. Solar radiation warms the surface, forcing air to rise to an atmospheric convective boundary, where it then cools. The denser, cold air parcel descends and generates a circulation that creates a suction effect.
As the Dust Devil picks up material from the bright dust-mantled surface, it exposes the darker basaltic substrate. These scribble marks will follow the prevailing winds and tend to cluster together as the lower albedo surface heats up more quickly.
Scientists are trying to understand the relationship between Dust Devils and craters and other topographic features that generate multiple wind directions.