I think so, but I'm holding back pending getting PanCam images (that is, the right PanCam images) to make color. The apparent lightness of the trenches in monochrome is probably heaviliy dependent on things like azimuth and sun angle--could just be "glitter" looking into sun.

I couldn't find any "true color" image sets, but I found a fairly useful set of IR+G+V PanCams from Spirit looking inside a trench:

That may be exposed subsurface material, but again I'm holding back, because it could be heavily-compacted due to spinning a wheel on it--reminds me of treadmarks I've seen after I've gotten my car stuck in the mud and spun the wheels trying to get out.

I couldn't find any Opportunity color images looking inside a trench. Closest thing I could find is treadmarks on the surface:

The lightness is definitely due to compaction.

I'm not sure these images provide any answers, but I was giving myself a break from the Workbench grind, playing with color, so I thought I'd show off...;-)

GeekNotes: Clicking each images displays a page with the browse image and a click-through to the large image. I put the "recipe" on the page for documentation, and I ought to explain the notation: (IR+G),G,(G+V) means that the R channel is based on the average of IR and G; G is G; and the B channel comes from averaging G with V.

Also, in taking the long view, I'm trying to figure out a uniform file naming convention. What I'm trying out is using the common root in the IDs of all component images, with the recipe appended:

1P129695417EFF0322P2261L2M1.jpg
1P129695620EFF0322P2261L5M1.jpg
1P129695514EFF0322P2261L7M1.jpg

becomes

1P129695_IR+G_G_G+V

I think this method will always form unique filenames. Time will tell, and I'm interested in what the image jocks think. It'd be nice if we could agree on a common "vocabulary", eh?