Thanks guys. I've just got another idea, which I'll test. As these aren't really hard, blocky rocks, which was the intention. Here's a version with the fractalwarp inv.masked by the road, and your little brook, Luvsmusik
That was the easy part; just paint in in a logical place and add some shaders.
Detail 0.7 AA7 soft shadows, 1.5 hours, using one compute terrain small patch. Nice and fast, I like that.
I also tried to make waterfall offf that cliffside on the right by populating a lot of glass stones on a card, but no matter what I did (rotate the pop), I always ended up with a series of evenly spaced vertical rows