You probibly have to change the funtion on the terrain to a more square wave type pattern then turn that terrain sidways. Or cheat in that add blocky terrain parts to your existing terrain. Just small ones stick right on the walls of the bigger one. If you want perfect looking textures you have to use a bmp picture of the rock, Your going to need a really big picture. Or again cheat and use one for the big terrrain and a different one on the smallish blocks you added above. Other idea get the rock on a picture then import it for the terrain height map. As long as you change the function to a more squarish pattern it will work.