...thin frost layers.
All over the image, dark dunes and dune fields can be found, in some areas covered by a thin frost layer. Interestingly, the fields follow a yardang-like morphology indicating the prevalent wind directions, influenced by the morphology of the surface. The provenance of the dark material on Mars is still poorly understood. It is believed that it derives from ancient buried layers of volcanic eruption materials. It can be found globally all over Mars. In some regions, individual dark spots can be found in the image. These spots could be a hint at another distribution process of dark material, specific to polar areas on Mars: CO2 jets formed by sublimation beneath translucent ice slabs that then eject geyser-like fountains of dark dust. Constant monitoring of these zones helps to understand the processes that steadily alter the appearance of the surface in the polar regions on Mars.