if you mean particulate regolith acting as a fluid to garner gully carvings, i find that very reaching a premise. that seems far more unrealistic and complicated an explanation than water flow. i know the premise is not necessarily your own, so don't take it personally. i don't fall into the camp that supports dry regolith acting as a fluid; not for this case anyway. the terminus and trough of the gullies is (to my layperson's eyes) exemplary of fluid dynamics due to liquid.