This image shows some of the dunefields of Mars.
Click on image for full size
NASA
Martian Dunefields
This is an example of the dunefields of Mars. The image was taken by Mariner 9. They are located in the southern hemisphere. They are evidence of planetary resurfacing by winds.
Sand dunes were also seen at equatorial latitudes by Mars Pathfinder and also by the Viking I lander in the Chryse Planitia Basin (check the large topographic map of Mars for the distances between these two landing sites).
The prevelance of sand dunes is an indication of the importance of wind to the erosion of the Martian landscape.
You might also be interested in:

There are two main weathering agents on Mars: wind and acid fog. Although acid fog can be very important, because large amounts of water are not readily accessible from the Martian surface, the action
...more
During the Mars Pathfinder Rover's exploration of the Martian surface, it traversed what scientists now call the "Mermaid Dune", covered with soils. The soil on top of Mermaid Dune seemed to have a dark
...more
On this map of Mars, the lightly cratered Tharsis Ridge is shown, as well as the heavily cratered Martian highlands (near the bottom of the picture), and Valles Marineris to the right. The volcanoes are
...more
The unusual global geography of Mars helps to explain the fact that water has been drawn from the southern hemisphere to the northern hemisphere of the planet through all of Martian history (that is, from
...more
The Martian geography is one of high altitudes at high southern latitudes and low altitudes at low latitudes. The ground is less frozen at low latitudes because it is warmer and water can evaporate. Thus,
...more
Separate from the Martian outflow channels, or the river valley networks, are large Martian lakes (600 km, or ~1000 miles across) which exhibit evidence of a periodic and catastrophic release of water
...more
This is an image of fog in a Martian canyon. The presence of fog provides evidence of water, and a water cycle on Mars. More fog has been seen in images returned by Mars Global Surveyor of the south polar
...more
The Martian climate is more influenced by the shape of the Martian orbit than the climate of the Earth is influenced by the shape of the Earth's orbit. The orbit of Mars is more elliptical than that of
...more