Plausibility of the "White Mars" hypothesis based upon the thermal nature of the Martian subsurface

The "White Mars" hypothesis asserts that CO₂ gas-driven debris flows were responsible for carving the outflow channels, the valley networks and the gullies on Mars rather than liquid water. This model further asserts that liquid water has been confined to the deep subsurface unable to find egress to erode the surface. We show that the subsurface of Mars, especially when major fluvial features formed, is unlikely to have been as cold as this model suggests and that liquid water would be present much closer to the surface than predicted by "White Mars". The assumptions of the "White Mars" hypothesis regarding globally-averaged crustal heat flow are below most estimates of the current thermal state of the Martian crust, and well below probable values 2 Gyr or more ago. Likewise, the assumed value of crustal thermal conductivity in "White Mars" is inconsistent with the CO₂ dominated cryosphere of the model.