This slope streak occurred in the time between a Viking image of the bottom of this crater ( 713A57 , which saw no streak) and a MOC image ( R12/01917 , as reported by Schorghofer et al. (2007) .

That paper suggested that the slope streak may have been caused by a dust devil that had passed by (its track is visible in the MOC image). Our HiRISE image shows that there isn’t a small hill or anything at this slope streak’s apex, but that the dust devil track really does intersect with the apex. It is likely that the dust devil may have caused this slope streak.

Dark slope streaks are visible in many places on the Martian surface, often where the dust cover is thick. One explanation for dark slope streaks is that they are little avalanches in the dust. The apexes of slope streaks (where they start from) are often at little hills or ridges on a larger slope, with the thinking that the dust here is already close to being too steep, and then any little perturbation will start one of these tiny avalanches. Small craters have also been seen at slope streak apexes.

Written by: Ross A. Beyer   (1 September 2008)

More info and image formats at http://hirise.lpl.arizona.edu/PSP_009192_1890

Image: NASA/JPL/University of Arizona