Liquid CO2 breakout and the formation of recent small gullies on Mars

We show that the action of a CO₂ suspended flow could have produced the recent small gullies on Mars, and, hence, that liquid water is not required. The model involves the build-up of a liquid-CO₂ aquifer behind and below a dry-ice barrier (dam/cap rock) in the pore spaces a few meters into the rock from the cliff face and on order of a hundred meters below the top of the cliff brink surface. Seasonal (or obliquity-cycle-seasonal) heating causes pinching out of the dry-ice barrier and rapid release of the liquid CO₂. Erosion of the gullies occurs as the rapid vaporization of the liquid CO₂ with entrainment of rock and clathrate-hydrate ice produces a density flow analogous to a terrestrial nue ardente.