Well this has been an interesting journey and it ain't over yet. I've never had an image fight me quite so hard!
I've learn't a lot about integrating World machine and Terragen, and come up with a lot of things I want to explore. I'm going to stop here (for the moment)to explore some of those ideas.
I need to improve the vegetation and explore some ideas about creating ice falls, the rock textures could be improved still and there are things I need to do with the water to add variety to the foam and add a greater sense of waterfalls.
All good fun!