An immense dune field covers much of the northern polar region of Mars. Often, after major windstorms, dark dunes of basaltic sands can be seen scattered across the polar region, some of them in the strangest places. Over time, a lighter pink dust covers many of these dark dunes. Eventually, as winter advances, dry ice is deposited on the tops of the dunes. By summer, this dry ice sublimates causing the heavy basaltic sands to flow downslope creating the pink landscapes with black spots or channels.
The later images show various fascinating landscapes that Mars Reconnaissance Orbiter HiRISE camera photographed over the last several years. Among them are photos of Cerebus Fossae, a channel that planetogists believe were created by floods of water. There is a photo of a dustdevil with a ghostly face peering back at MRO. Some of the later photos depict the "spiders" of Mars. The last photos show the southern polar region which is markedly different from the northern polar region.
These images are courtesy of NASA, the Jet Propulsion Laboratory, and the University of Arizona. They can be found in the HiRISE Catalog which contains over 11,700 images of Mars surface features.