Dark slope streak

Dark slope streaks are narrow, avalanche-like features common on dust-covered slopes in the equatorial regions of Mars. They form in relatively steep terrain, such as along escarpments and crater walls. Although first recognized in Viking Orbiter images from the late 1970s, dark slope streaks were not studied in detail until higher-resolution images from the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) spacecraft became available in the late 1990s and 2000s.

The physical process that produces dark slope streaks is still uncertain. They are most likely caused by the mass movement of loose, fine-grained material on oversteepened slopes (i.e., dust avalanches). The avalanching disturbs and removes a bright surface layer of dust to expose a darker substrate. In a study of over 500,000 dark slope streaks, researchers found that streaks were more likey to form in dusty areas instead of moist places. The authors also determined that slope streaks modify less than 0.1% of the martian surface, but transport several global storm equivalents of dust per Mars year; hence, potentially playing a major role in the martian dust cycle."

The role that water and other volatiles plays, if any, in streak formation is still debated. Slope streaks are particularly intriguing because they are one of the few geological phenomena that can be observed occurring on Mars in the present day.