Wonderful training here; love the way youve sculptured the landscape; you seem to have wonderful control over that element of Bryce tools. Overall the mood is excellent and well executed. The color bands are very noticeable but I have no idea how they came about or how to get rid of them but in some ways they tend to add to this piece. What I would suggest is that you make a copy of the file and re-render with a different sky, and then re-render that with the same sky. Your original file may have been corrupted in some way during the creative process, so just copy and re-render that might fix the problem. But all n all this is an excellent work of art. Also I might add it would look really great with some Native Americans paddling through the water in a canoe.

This picture is so dark that I can't really see the banding, only a hint of it. I'm guessing you overcompressed the picture when you saved it. Reduce the physical size a little bit and save at a less compressed setting. You have to do this with the original. This copy won't correct itself.

Actually the color banding wasn't a result of compression, seeing as it's on the original bitmap. :-(