Thank you for your comments and advice. I'll see what I can do about the mountains. I'm still trying out the suggestion I got before to see how I can make that work.
As to the scrub-- thanks again. I couldn't figure out why it was bugging me so much. Right now I have it made with an applied layer mask and something else. I'll look through the resource forum for a good brush and try that out instead.
As for the rivers, yeah... I still need to do those. Part of the reason they're not set yet is because I want to make sure they pass river police standards and partially because bevel isn't something I've used in gimp before. I'll search the tutorials. Thanks again.