Susan J. Conway Tjalling de Haas Colin M. Dundas Stephen R. Lewis Jim McElwaine Kelly Pasquon Jan Raack Matt Sylvest Manish Patel Lonneke Roelofs 2024 <p><span>Martian gullies resemble water-carved gullies on Earth, yet their present-day activity cannot be explained by water-driven processes. The sublimation of CO</span>₂<span>&nbsp;has been proposed as an alternative driver for sediment transport, but how this mechanism works remains unknown. Here we combine laboratory experiments of CO</span>₂<span>-driven granular flows under Martian atmospheric pressure with 1D climate simulation modelling to unravel how, where, and when CO</span>₂<span>&nbsp;can drive present-day gully activity. Our work shows that sublimation of CO</span>₂<span>&nbsp;ice, under Martian atmospheric conditions can fluidize sediment and creates morphologies similar to those observed on Mars. Furthermore, the modelled climatic and topographic boundary conditions for this process, align with present-day gully activity. These results have implications for the influence of water versus CO</span>₂<span>-driven processes in gully formation and for the interpretation of gully landforms on other planets, as their existence is no longer definitive proof for flowing liquids.</span></p> application/pdf 10.1038/s43247-024-01298-7 en Nature How, when and where current mass flows in Martian gullies are driven by CO2 sublimation article