The way you've made the ground completely black doesn't look that great, perhaps with softening the part where the sky and ground clash with some glow models would make the ground look less edgy.
By making this part look better, it would not look like a badly drawn black spot.
Also adding other floating rocks with structures or not, would fill the empty space that is left in the sky.
(And double posting is not allowed, you should use the 'Edit' - Button to add your text to your earlier posts. It's nothing too serious but you'd better keep that on mind)
- Now that I mentioned about editing, I suggest to create only one thread for your terrains if they come within short delays, so there would be less threads created by you. With editing you can always add your new terrains to the old message that includes your other terrains.