The main terrain is actually 1 terrain with "mediterranean hills" preset applied, then duplicated. The resulting terrain was clipped lower, smoothed, eroded, then given the "desert rock" preset, and duplicated. That third terrain was clipped even lower, smoothed, eroded and given the "sandstorm" preset. I thought that the green showing throw the other two materials at the bottom resembled mossy growth on the north side of those slopes. I had a link to this guy's site that explained the technique in detail (and with much better results) but I've lost it and haven't been able to find it again in my searches... I was working from memory. I believe EricofSD gave that same link in response to someone's question six months or so ago, but I haven't found that thread again either. Maybe he'll see this and remember what I'm talking about.