Good deployment of foliage and stones, and good overall realism in scene. I like those clouds (I'll check them out, for sure). Your boulders have some undulations to encounter in their travel, so they may decide to stay put. The actual Racetrack terrain is a lot flatter and given icy conditions and strong winds, movement is credible. A good project for a webcam, I'd say, to catch the blighters moving. Thanks for the info, Bob. Fascinating stuff, and excellent work on your render.
John