Your grass tiling is crap, the canyon doesnt look like a canyon its to green. I recommend doing something similar to this style I made a while back to simulate a dried up river. It would definatly make the level look more canyon like. All in all I like that you're making a canyon not something alot of people do. Just need to focus on how to make it look realistically like a canyon.
http://forums.graal2001.com/forums/a...&postid=832555