Unnamed Crater with Ridges and DD Tracks (natural colors; credits: Lunexit)

This image shows two features of interest on the floor of a large impact crater. The first is the set of roughly parallel ridges on the crater floor that point towards the crater center north of the image. These may be Inverted Stream Channels, where old streambeds became resistant to erosion due to cementation or simply deposition of large rocks. This is consistent with the slightly wavy, sinuous shape of the ridges, but these examples are not particularly well-preserved.

More recently, this site has become blanketed by dust, settling out after Global Dust Storms. This obscures much of the fine-scale geology, but allows HiRISE to see the effects of a recent process: Dust Devils. These have left the dark stripes across the surface by disturbing the dust cover. Most followed straight paths, but a few loops or turns are visible. Dust Devils may be an important factor in the Martian climate system because they lift dust into the atmosphere, helping to trigger larger Dust Storms.