In the bryce scene I duplicate the quarter ring to make a whole ring. I duplicate it and put it just under the first ring then I rotate it a bit for the rocks not to be replicated at the same place and to give a "random" look. I set the lightings (2 radial lights in my scene) and I do some part render to check that is't ok... That's all By the way I've set the terrain resolution to 2048x2048.. so be carefull to have enought memory if you don't want bryce to crash ;-p cheers