Hmmm... try moving your light source? All the shadows normally go the same way, on a map, but this is a ring, so..

If it's noon, on the island, the sun will be directly over the island and all the shadows go *away* from the center of the island.

Right now, you have 2 problems... one is that the shadows all slant to the southeast, which gives the impression of a line in that direction. On *this* map, it makes it look as if the land is slanting down.

Second... the emboss thing is doing the same as the shadows... it's all going one direction (mostly) which is adding to that effect...

I'd get rid of the embossing and do all the shading/etc by hand. If I wanted something fast and easy, I'd probably use a texture (slate maybe?) with a large, soft brush, to shade the darker areas of the bottom half of the ring, and the lighter areas of the top half, which might give just enough of the effect to make it feel right.