make the bottom of the wall darker ..and take away the bottom wall line  and have the grass just go up it .. i meaning the bottom wall line just above the grass.. it gives the up right wall to much of a box look like it stops there then the shadow underneath is the other side of it ..

Argh you're right! I think its because I show the grass at the bottom, which throws off my perspective 

I can't tell whether the rocky bits are walls rising out of the ground, or if they're level with the ground surface. It looks like the former around the wall, and the latter around the grass.