Kind if a weird piece of Styrofoam I picked up at a train show
for a dollar. Looks like it could be mountain rocks to me.

I often use Woodland Scenics Plaster Cloth to cover pink foam, MDF and other materials as a base layer in preparation for other plaster and scenery products. I've noticed that occasionally, after the Plaster Cloth dries on smooth, flat surfaces, it has a tendency not to stick and might start to lift. Since I had a relatively large area of smooth pink foam and MDF, I thought I'd try to first glue on a few pieces of course, mesh sandpaper (the kind that somewhat ironically is used to sand drywall plaster).

Using a foam-safe glue, I put a few pieces down - without the intention to cover the entire area. I figured that the plaster from the Plaster Cloth will seep around the strands of the mesh, which is glued to the surface and create a strong bond. I don't know if it was really necessary, but after the Plaster Cloth dried it seems to be very secure.

I've made some progress in planning how I'm going to configure this section where New Mexico, Arizona and California are represented in an area not much larger than a place mat. Some additional Sculpt-a-Mold helps me to envision how the river will evolve.

I've also done some testing (and modifications) to make sure the large cars of the Super Chief can comfortably make it on tracks with a smaller radius curves than ideal.

Since there's going to be a mountain range in the center of the layout, I thought having the trolley run through a tunnel would be a nice way to limit its visibility. So it will enter the tunnel in California and appear in Chicago, where imaginative viewers will see a Chicago trolley emerging on the El (a.k.a. the "L").

Working without a specific design can be challenging as in "What should I do next?" But after trying several different approaches, the river and surrounding mountains are taking shape, blending the older section into the new layout.

I built a small bridge out of leftover parts I had from my previous layout. I also felt that a dam is a must on the Colorado River and tried several techniques for creating it. The winner is a piece of PVC pipe, cut down and covered with .010" styrene.

To my knowledge, train tunnels don't exist between LA and Arizona, so I didn't want the tunnel portal here to stand out. I made a small and simple one out of foam and a sheet of styrene rocks. It will eventually be blocked with a bit of foliage.

I was able to use one of my little test mountains to make hills and a mountain pass. Then I did a bit of landscaping to the existing Southwest section. Although it's not complete, it's getting pretty close. Foliage and river water will come soon.