I can see what you mean, it could also be the angle in which the rocks are sticking out of the earth though. Now i'm really confused... guess i'll need a second oppinion!
Hey there, this is cool! However, there are few really big problems! If you are trying to make this platformer tileset, the rocks have turned out to be in rpg perspective.
It might be only me thinking that though.
I think it's good, there are plenty of platformers that have textured platform walls that appear to stick out a bit. I like it! Only thing I can think to improve would be the connection between the rocks and the grass. The rocks don't really appear to support the grass because there are still nooks and crannies in the transition.