In some places, both bright and dark streaks are associated with a single topographic obstacle. Bright depositional streaks form in the waning stages of a dust storm, then dark erosional streaks form by eroding the thin layer of dust that settled out everywhere after the dust storm. The dust composing the bright streaks, once emplaced, is very difficult for the wind to remove, so bright streaks can easily survive the small amount of erosion needed to form the dark streaks. The streaks need not have the same alignment; each reflects the wind direction during their formation.
Location: Latitude –28°, Longitude 245°, in Hesperia Planum. Viking orbiter photograph 553A54, NGF orthographic version, red filter.