I'm going for a desert type terrain, where the wind has swept the sand off the cliffs and we can see the dirt beneath it. The next step is adding some bump maps to make it look a lot more detailed. So drag the whole Mix map from Diffuse Color slot and Copy it to the Bump slot of our GroundMaterial.
Let's go into this new Mix map and modify it to suit the Bump we expect to
achieve. For Color #1, add a Noise map. For this Noise map we need to set the Noise type to Fractal, Size to 10, Levels to 10, High Noise Threshold to 0.7 and the X axis Tiling to 2.
Now, go back to the parent map, the Mix map for the Bump slot. For Color #2, add another Noise map, and for this one set the Noise type to Fractal, Size to 2, Levels to 4 and we will also be changing the two colors to R:0 G:0 B:0 and R:60 G:60 B:60. This is so that this noise map is weaker as it will be assigned by the falloff to the sandy areas of the terrain, where we don't need too much bump.
Another change we will make for the bump map is in its Falloff map in the Mix Amount slot. We need to move the first point of the Mix Curve to the top, like this