Dunes are also common on the Martian surface, especially around the polar ice caps. Dunes could occur in small areas such as inside a crater (Figure 5.4). The dune field is indicated by an arrow. Also notice that crater rims on Mars are often not as sharp and pristine as those on the Moon or Mercury. They were probably degraded by the erosional effects of particles suspended in the blowing atmosphere.

Dunes also occur on a larger scale (Figure 5.5) . This image is about 60 km across. Notice the barchan dune field on the left, which eventually merges into a transverse dune field. There is also a smaller dune field towards the upper right-hand corner of the image.

The Mars Global Surveyor was able to obtain a much higher resolution image of a barchan dune field as shown in Figure 5.6. Another spectacular view of a transverse dune field is shown in Figure 5.7. The lack of craters in this photo indicates that the dune field must be relatively young. Linear dunes are also found on Mars (Figure 5.8), as are smaller scale sand dunes, which exist on valley floors (Figure 5.9).