Starship Asterisk*

Thank you Neufer for your interesting answer!
Quite puzzling to me too is the fact that the dark sand - outside the cascades - appears in isolated spots, and that those spots seem to be connected to frozen areas. Shouldn't they appear in warmer melting places?

I don't think that the black sand is the one that felt in cascade. If you look to this picture of dust evil trails, you can see that actually the black sand appears when the pink and clear sand is removed: http://apod.nasa.gov/apod/ap091021.html So the upper level of clear sand should be the one tha...