This image from the HiRISE camera aboard the Mars Reconnaissance Orbiter (MRO) shows streaks of dark-colored material lining the walls of a trough (left side) and tapering out onto its floor. One of the few currently active geologic processes on Mars, this streaking may be caused by finely-grained soil moving downhill in much the same way as a liquid would, exposing darker ground underneath. As the streaks age they get lighter in color, possibly by the gradual accumulation of dust and sand covering them. Click here for a full view of the area that HiRISE imaged…there’s sure seems to be a lot of streaking going on on Mars! 😉

Read more about this process on the University of Arizona’s HiRISE site here.

Image: NASA/JPL/University of Arizona