Thanks, all.
For the time being I'm trying to develop a robust surfacing for the vertical cliff surfaces than can be used as a base to build a more complex scene in lighting, coloring, objects etc. For these next two I did some fine tuning of the vertical surfacing, and hit the random seed buttons a few times, and played a bit with the scene lighting to give a bit more light in the shadows. So far the surfacing seems reasonably adaptable although, occasionally, the displacement from the main redirect shader gives extreme overhangs such as the one in the upper left in WIP - 8.