For this image only:
http://hirise.lpl.arizona.edu/PDS/EXTRA ... browse.jpg
and proceeded to talk about its being mounded up rather than a depression.
I clicked on your link, and clicked on the image once to enlarge it, and made a screenshot of a typical location along the "canyon" or "rille" or "mound" - whatever it is.
Looking at the shadowed striations in the shady right side within this structure, which are likely roughly vertical but photographed from an oblique angle, I'd say that they clearly indicate a perspective view of a depressed trench-like structure. There appear to be sand dunes along the floor, lit in a fashion and from an angle consistent with that of the craters along the upper edge of the canyon. How there are craters formed there, without their impact having caved in the walls of the canyon, can only (so far as I know) be explained by EU/EDM examples, not ballistic trajectories of large chunks.