The next scenic step was to try to make some rock like features around the tunnel portals. It went fairly well, using putty and water colors. However, the hillside was quite steep for a long stretch along the track at one of the portals. This led to an equally long stretch of rock face, and my rock creating talents was not really up to that challenge. Simply put , it did not look natural.
So I decided to hide the problem with a retaining wall. I made it from plaster, as I did the tunnel portals themselves and as described in this post. Here is the molded wall, before weathering.
You can see the discarded rock face behind it. Next came painting and weathering, and some gravel and sand between it and the rock.
Eastbound train emerging
I have also been preparing the ground by glueing rocks here and there, in a kind of random fashion.
Creating small rivers of white glue and water mix in the process...