How can rocks be transported hundreds of kilometres by gas?
This is one of the difficult points with the “White Mars” model. I can demonstrate on Earth that density flows from volcanoes have transported boulders for tens or even hundreds of km. However there are no examples of volcanic density flows (pyroclastic flows) persisting for thousands of km. One reason for this is that the energy for a pyroclastic flow comes from hot rock which cools after many minutes or at most an hour. Even with supersonic flow speeds this limits the travel distance to at most a few hundred km. On Mars, the energy source is degassing of CO2-rich ices. This is constrained by the rate of energy supply to the crystals, which is controlled by internal friction. If the flow starts to die, then friction increases and the grains get crushed and warmed, so they give out more CO2. Obviously, a more complete scientific analysis of this process needs to be completed, which is part of the further work. At the present time, it isn’t clear whether the Pathfinder boulders have lit
