Actually, this is a nice "grab bag" image that contains a variety of geological delights. Thanks for posting it, Dan.

IMHO, the dark streak is clearly a dust avalanche scar; there are numerous examples all over the planet. The "white plume" to which you refer appears to be an erosional scarp associated with mass wasting. The plumelike appearance seems to be due to the fact that the scarp to the south is at roughly the same height with a spur on the opposite side of the ridge line, both of which have similar albedo/illumination geometry. The "geothermal domes" to which you refer are simply talus aprons resulting from downslope transport of debris. I've many features like these in the central portions of the ancient valley networks.

Alex R. Blackwell
University of Hawaii