Slope streaks on Mars are typically dark, extend downslope for up to ~2 km, are <200 m in width, show no detectable relief, and have been observed to form/change over less than decadal time periods. Mars streaks occur exclusively in regions of low thermal inertia, steep slopes, and only where peak temperatures >275 K; changes are observed only if the interval includes the warm season. Mechanisms proposed for Mars slope streaks include dry dust avalanches, wet debris flows, and erosive fluvial processes from spring discharge. We investigated very similar slope streaks in upper Wright Valley of the Antarctic Dry Valleys and interpret their formation to be due to snowpack and near-surface melting-derived saline water traveling downslope along the top of the ice table, wicking and dampening the surface to cause the streak, a new mechanism that should be seriously considered for the origin of slope streaks on Mars.