Mechanistic understanding of surface processes on Earth can be applied to similar processs on Mars and Titan. Our work on Mars has included the investigation of canyons with amphitheater heads that have been used previously to infer groundwater seepage with important implications for astrobiology. We have been working to understand the mechanics of bedrock-erosion processes and the connections between process and form, using observations of canyons on Mars and Earth (Hawaii, Idaho, Colorado Plateau), theoretical modeling, and physical modeling. Results indicate that groundwater seepage should not be inferred from canyon head form. Other work on Mars includes reconstruction of Martian paleo-flow from sedimentary strata, crater lakes, and delta deposits.
Branching valley networks near the landing site of the Huygens probe on Titan (Saturn's largest moon) imply that flowing fluid has eroded the surface. The fluid was most likely methane, and the eroded material was probably composed mostly of water ice. We show that the properties of these materials at Titan's surface and the morphology of the networks suggest that the valleys were eroded mechanically by surface runoff, and use the valley network morphology to estimate the methane precipitation rates required to form these features. Other work includes rescaling sediment transport laws developed on Earth for Titan, and evaluating the liklihood of waves on Titan's lakes.