I've been having some fun the last few days trying some scenery making on the left half of the EVRR, but I thought I'd get serious and check what I was doing a little more closely against a reference photo. Under the ridge, over on the left, you can see two stone tunnel portals. One is over the inlet to the stream that feeds the lake. The other is a little harder to figure out what it's for. I'm thinking it's for the roadway that parallels the lake's far shore. My guess is that both those portals are made by scribing a stone pattern into some balsa with a hot knife.
The other item I need to add is that rock wall that runs parallel to the track on the upper level and also runs behind the Rocky Ridge depot. Now I need to run and start carving some more foam. And maybe some balsa :-)