false color of Purgatory 'trench'
Here's a false color 6 filter view of Opportunity's deepest trench yet (why not put a bit of a positive spin on the whole ordeal).
The dune face in the lower right quad of the image is darker than the rest of the scene in all the infrared and visible red frames, but I should know better by now than to assume it is any more than a very slight difference exagerated by the image stretching. Or, an effect of the illumination angle, similar to Yogi's "red face, blue face". Hopefully this will be the first of many close-ups of the trench, as there might well be some good science down at the bottom of that hole.