I'm not sure what I am doing, but I am not going to let that stop me!

[Revock]

it's interesting, but, for 300 mile wide and at the height to see that much area, I personally would reduce the texture size and maybe its a bit too vivid in color, at first glance it gives the impression that the land is even with or higher than the mountain texture, light should hit the mountains more than the valley I think. I would isolate the land texture and try to make a gradient mask, dark in the middle and lighter to the edges which would i think give the impression of depth in the middle, more experienced hands would say exactly and accurately but i believe its a simple radial gradient, maybe a shaped angular in hard light mode, try to get a darker center with a sense of valley walls rising up and blur as desired to soften the walls. i usually try every mode till i get what looks close to what i want so off hand i can't just pop out a mode to suggest.