Had some render time to spare so I wasted a night and rendered a test of sorts...
http://www.youtube.com/watch?v=xQsAj6olxgc note I disabled the atmosphere to get a quick render. It rendered @720p but I forgot to bump the cloud samples...
Very cool but the erosion/sediment appears to be moving in reverse, don't you think? I do think this is just a TG idiosyncrasy and nothing you could have helped, though. Nice test! :)
Actually the erosion was made in geocontrol. The thing you see is something I added just before I clicked render and went to sleep.. last minute bad ideas ;)