There's a very interesting high resolution color photo [4.3 MBytes] of
the bedrock near MER-B. It's definitely stratified. There's also these
isolated black rocks laying about (looks like they're ejecta from a nearby meteor
impact). I've looked closely at the stratified rock. Again I'm no geologist.
I've seen rock like this near volcanos (layered ash) and in the desert near
lake beds (water sedimentation). Right now, it's only pointless speculation.
However in a few days, MER-B will get a close look at it with its microscope
and spectrometers. If it's full of olivine then it'll be safe to assume
it's ash. However if there is no olivine and there's rounded pebbles in it
then we have a very interesting result. I'd like to hear what our resident
geologists think about this.

Gary