Planet-wide mapping of lobate debris aprons and other similar flows on Mars shows a strong concentration in two latitudinal bands roughly 25° wide and centered at 40°N and 45°S. This distribution supports the idea that these flows form when erosional debris is transported downslope and becomes mixed with ice deposited from the atmosphere, as these latitudes should receive high seasonal H₂O frost deposition relative to the rest of the planet. Flows are found in the northern hemisphere band wherever old highland surfaces occur but are found in the southern hemisphere only near the two major impact basins, Argyre and Hellas. These areas are apparently characterized by mass wasting that is rapid relative to most of the southern hemisphere highlands. The rate of mass wasting may be related to the degree of consolidation of highland material.