Abstract

Two key pieces of geologic evidence for liquid water on the ancient surface of Mars (>3.5 Ga) are branching river valley networks and a record of paleolake basins. Of the >250 early Mars paleolake basins identified from orbit, the majority (>85%) are hydrologically open, with an outlet canyon that connects with downstream river valleys. In this talk I will present analyses of the topography and geometry of martian paleolake outlet canyons to test the hypothesis that they were incised by catastrophic lake overflow flooding. Included in this analysis is a comparison of our results to observations of breached lake basins on Earth to test whether observed geometric scaling relationships are consistent across the two planets. Finally, I will present an analysis of the global contribution of lake outlet canyons to valley erosion on early Mars, and discuss implications for broader martian landscape evolution.