Hi Incarnadine, thanks for your reply. Initially I also thought along the same lines as you, but I have made quite sure that the cutting cube is noticeably larger on all counts than the ampitheatre terrains - which is why I'm stumped as to just why particles are being left behind. shrugs Thank you for your suggestions however. smile Johnpenn - thanks very much for your suggestions. I have double, triple and even quadruple checked that all the terrain steps are solid. Everything is as it should be which is why I can't understand why the small particles are being left behind. Also, your suggestion about just using one terrain for the whole ampitheatre - I too would have loved to have done that (it would have made life sooo much easier, LOL) but I don't really have any decent graphics program to produce the decent number of grayscales. Also, I am unsure as to how to keep each step at exactly the same height by just using grayscale data. If you have any suggestions on how I could do that then I would love to hear them because I would certainly prefer to use one terrain compared to the many many I am using to produce the ampitheatre you see above. Again, many thanks for your suggestions, both of you.