What is the dark material wafting around in these "familiar dimples?" This super fine dust sure behaves like a fluid. It settles to the bottom of the dimples with hardly any being deposited on the sides. Yet it has ripples sometimes. Sometimes, its perfectly flat and looks ice like. Sometimes it almost seems transparent and hovering. I hope they get around to analyzing this important material soon.

I was reviewing Malin gully photos, and in looking at some with debris aprons I came to the conclusion that there might not be any water involved. Dust avalanches could carve the gullies. That would explain why they are more often located on slopes that face away from the equator. Those slopes get more water frost, so more chemical and physical weathering, and more dust formation. This could accumulate in still periods between the dust storm outbreaks, then when the wind finally picked up again, it would trigger dust avalanches where the dust was sufficiently abundant. The other, frost free slopes, would not have enough dust formed for avalanches, but the dust would blow away in the storm. (This model requires long still periods between storms).

Specifically, in this image, the apron seem to have over ridden the dunes there in the run out zone. If it was water born deposition, I would expect it to undercut and destroy all of the dune. Even more so of the polygons, they seem to be buried, and show up even though they are in the apron zone. This suggests dust deposition, to me. While I don't doubt that Dr. Malin has considered this, and I have reviewed but a liny fraction of his great work, I have seen no specific mention of dust avalanches in the explanatory captions so far. Seeing the fluid like dust of the dimples makes me reassess the speculations (including my own) about possible roles for flowing liquid water or solutions on Mars currently. The darkness of the "streaks" may just be the exposure of this much darker material that underlies the planet wide thin light colored dust coating. I still think that the lower dark material may contain much water in deliquescent minerals, brines, and acid solution, and that this makes it so dark and wind resistant.