Thanks for the positive feedback, much appreciated!
Yep, the cliffs are a combination of pine bark chips, cork bark sections cut from a pet store log, and also floral foam and pink insulation foam cut into jagged, random shapes.
The road are made from thin utility carpeting, the kind you can get off a roll and buy by the foot at a home store. I bought a big slice of it.
I basically took the carpet and cut it into a bunch of random pieces. Then I flipped the pieces over and painted the road colors on the back side (the vinyl/plastic side). I did a base color of brown and then did two stripes of an off-white down each piece. Finally I added some static grass to the center of the road pieces to simulate some random grass growing down the center of the road.
A really cheap and easy way to do a lot of road sections! With the piece of carpeting I bought, I did about eight feet of road and also had enough carpeting left over to do about eight feet of river sections using the same method.
The reason that I made modular river sections out of the carpeting as well as making terrain boards with permanent rivers is that I needed a way to create rivers for winter boards. Since my Mod Podge rivers are carved right into the terrain boards, and are all part of green spring/summer boards, I needed alternate rivers to use on winter tables.
For those I just painted them a dark blue and did some white drybrushing over them. I'll post some pictures of the rest of the road system as well as the river pieces.