Slope streaks on Mars represent a currently active geological process. Various theories for slope streak formation have suggested that slope streaks form by disturbing only a thin surface veneer, or by staining of the surface, preserving pre-existing topography within the streak. Theories also vary as to whether the formation mechanism requires the presence of water or another liquid. We present observations of a slope streak that reveal topographic mounds within the streak. These mounds do not continue outside the streak, and we suggest that they formed with, or immediately after, the slope streak. We use estimates of the total volume of mounds in this particular streak, compared with the estimated excavation volume, to extrapolate to a global sediment transport rate from slope streak formation. If this slope streak is typical, then this calculated rate is greater than estimates of the total volume of material transported by dust storms each year.