As we're aware, White Rock-like deposits are found in many craters scattered across Mars; in all of them, the deposits are very similar in appearance, erosion, age, and being surrounded by and/or interspersed with much darker material (conventionally referred to as "dust" or sometimes "sand.")

The origin and composition of this "White Rock" material is mysterious. It does not seem to represent material that is found outside these craters, does not seem to be "indurated dust" (although it could be), does not appear to be hard rock or bedrock, and does appear to be actively eroding by wind-action.

The TES study used by Ruff, et al, told us little when it was published and still tells us little. The instrument's resolution was too coarse to be particularly useful then, and its inability to distinguish between surface and atmospheric carbon (even when corrections were made) was extremely frustrating for those who were looking for carbonate deposits. Yet THEMIS hasn't helped much to resolve the situation, either.

Based on the appearance of similar deposits in other craters, I asked some time ago whether they could have been erupted from the interior. (You may note this is a theme of mine! ;-) They appear to my eye to have originated as fluid material like mud. Well, why not mud erupted from below?

Also interesting to me is the dark material always found in intimate association with these "white" deposits. What is it? Is it an erosion product from the "white" deposits. If so, how?

The appearance of the dark deposit around "White Rock" itself looks like there is a 360 degree "wind" that blows from the formation somehow. But that doesn't make sense. How could it happen?

This is one reason the formation was once thought to be ice. Sublimation/evaporation might "blow" away from the formation in all directions. And moisture could be darkening surfaces as the sublimation/evaporation continued. But I think it has been fairly well established that the formation could not be ice.

We still cannot be certain these formations are or are not carbonates of some kind. It sure would be nice to find out!

Cheers, BRFelix