Jeeze. Your images are always so incredibly beautiful, Robert. Everything else seems so clunky by comparison.

Interesting blues. And so much blue. I note some of the spheres appear to be whitish/beige, while most are blue.

The "white" in the Spirit trench appears to me to be real, not a reflection or artifact from compaction. I say that in part because of the chunks of "white" thrown up from the pit onto the mound of "soil". They have the same sharp-edges as the material in the pit. And it looks as if the Spirit wheels have fractured and disrupted a layered "white" material down there. Compaction is certainly a possibility, but whatever would compact in this manner as a result of rover wheels could not be the same composition as the sandy soil, could it?

A quick survey of Gusev orbital pictures shows what could be whitish exposures and dune-like formations throughout the crater, though there is actually more dark material visible from orbit than whitish material.

In Meridiani, the whitish exposures are omnipresent. Many, many craters show whitish exposures on their rims and some even seem to show "white" layers visible from orbit. Some craters also show whitish streaks.

Given that Gusev is just south of Apollinaris Patera, a volcanic structure that seems to be associated with chaotic outflows, I wonder if Apollonaris and Gusev and Ma'adim Vallis form some kind of unit. Could Ma'adim actually be an outflow channel?

Cheers, BRFelix