Most ballasting, and roughing in a canyon

This is another take on ballasting - finer ballast in the center, rockier stuff outside a little.  Per typical narrow-gauge, the center area does have ballast on top of the ties (actually done to encourage water to run to the outside, when ballasting with dirt or other materials).  Notice the two tie colors... after review by other authorities in the house, the tan color will be used for most of the trackwork going forward.

So here's a close-up of some actual trackwork.

My process:

1. Wash the ties with soapy water and a toothbrush (removes the mold release agents from the plastic ties, for better paint adhesion).  
2. Paint the ties with grey Gesso (normally used to prime canvas for art paintings).  I've got to paint the visible sides and edges of ties w/ this... rather a pain, but the cost of avoiding fumes from spraying).
3. Using a brown Sharpy permanent marker to color the rails.  The color isn't too bad, and provides a coat that darkens the rails and helps the real color work (later).
4. Paint the ties again, with a wash of grey-tan acyrlic.  I'm using Martha Stewart (stop snickering!) Multi-Surface craft paints; that line has a couple of nice warm greys and browns.
5. Use some other colors and pick up some of the ties, for variety.  I used a second coat of the tan, and a darker brown.  I have a very light tan that's also useful, but that I didn't use here.
6. Finally, paint the rails again, this time using a Floquil Rail Brown paint pen.  I couldn't get this to cover properly without first using the permanent marker, and the brown shows thru a little sometimes, which looks ok.  Still, I needed two coats w/ the pen.  The result is what you see here.  Odd-looking now, but should look good w/ ballast added.

With the track finally painted, I moved on roughing in the canyon scenery - basically a deep canyon with both the track and a river winding through it. Here's the river (see above photo), running into a deep canyon.  My idea here is to intentionally prevent the view from seeing all of the river, or canyon, at one time.

The river exits under RGS Bridge 42-A.

Above, this shows the river exiting under RGS Bridge 42-A.  There really was a river on Keystone hill, running out under 42-A, but obviously the topography was different.  I'm after interesting visuals here, not an exact duplication of the prototype hillside, which would be less interesting in this greatly compressed space.  The river, from this view, will twist right and out of view behind rock walls (not yet roughed in behind the bridge).

So here's a view looking down the track, thru part of the canyon.

Above is a view looking down the track, thru part of the canyon.  The river is behind and to the right, and bridge 42-A is the center section, without the painted ties.  My idea here is to have a ridge following along the left side of the river, and crossing the track just beyond the bridge, forcing the track to go into a narrow cut.  I'm really trying to create the illusion of trackwork threading the terrain, rather than just having terrain filled in around the track.  Beyond the bridge, the track would pass into a second set of hilly canyons.  The visual here should be looking into the cut to see the track; it'll be somewhat blocked from side viewing in that small cut.

Above is the same section of track, but from the other side.  Here, the river's on the left beyond the cut, and bridge 42-A is at the very top of the track that's visible here.  I'm sticking some of the cardboard very roughly here - just trying to visualize the overall sight lines and view blocks.  I'm using drywall shims, btw - what you see here is less than two 50-piece packages - about $8 or so at Menards.  And a LOT easier than cutting all this cardboard!  It's really strong too.

One last shot - river on the right again

One last shot - river on the right again.  You can see how the river is descending in a canyon that's getting deeper, with rock walls getting very steep.  The hillside along the track is also gradually getting steeper, building to the cut beyond the bridge (just visible as the track curves out of sight to the right in this shot).  And again, although this is only about 10' of track, the curves and view blocks will - hopefully - make it seem much longer.