This view of the developing module was taken with it set at the standard 50" height. The lower shelf is installed and some initial layers of foam installed to provide a base for building up the canyon. Additional crossbeams serve to support the lower shelf while provide significantly more strength to the overall module structure. You should be able to see that I've also embedding a couple of braces that will be enclosed in foam as the canyon builds up.
As suggested by one of my CZM mates, the addition of the foam is also providing a stiffening effect so I'm not planning to add anymore wood supports until I've added the rest of the canyon walls in case it not really needed.
On the main level, I've added 1x2 wood below the edge of the thin hardwood surface on which the surface foam sits. My intention is to add a thin side surface mounted to this wood and covering the exposed foam, following the final edge terrain as it goes up and down.
This next view shows the developing canyon from the other side. The visible foam at the narrow portion of the canyon is about 10 inches (9 inches to the top of the visable wood beam) below the track surface level. The wider section is currently about 13 inches below the surface. I expect the depth at the narrows to be about 7-8 inches with the depth at the wide end to be about 12 inches or so. Between the two ends are planned two waterfalls, the upper one much shorter than the other with the upper one relatively close to the bridge and the lower one approximately in the middle portion of the canyon.