appears to be soft, thick, very fine grained material, not exactly dust, more analogous to flour; it seems almost viscous, adhering to itself (and other things) under pressure. The material mashes down easily (note the airbag imprints as well as the wheel tracks) exhibiting remarkable imprints. This indicated the material is relatively fluffy on the surface, not compacted until compressed.

This dark material is visible throughout the scene, and it can be extrapolated to be all over Meridiani, always in association with the "white" material we see in the blocky "bedrock". Orbital views elsewhere in Meridiani show the "white" layered material forms substantial mesas and outcrops, many of which have been heavily eroded. The layered material itself seems to be interbedded with the dark fine grained material, though that is not certain.

The fine grained material does not appear to be "dust." It actually reminds me of graphite, or possibly very fine metal shavings, but I'm all but certain that's not what it is. I'd like to know its actual composition. "Dust" on Mars seems to be quite different, both in color and in texture -- and no doubt in composition.

Dust devils may cross this material from time to time without leaving the tell-tale tracks we see in some other areas. That may mean this dark fine grained material is nevertheless dense, thick, and heavy, and that it is not a loose coating but a relatively deep layer.

It does not appear to be "wet" in any usual sense -- though it might behave as a dense fluid under certain circumstances.

The question of origin is open. Where has this stuff come from, and what is it? Could it be an erosion product? Or is it vocanic from a source or sources unknown?

And what is the composition of the "white" blocks?

And how did all of this wind up together in Meridiani? Is it related to the crater formations where we see associations between dark relatively fine grained material and hard, layered "white" material?

Could something other than volcanism be responsible?