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.