In the Inspector window, click on the Coloring foldout to open it, you will see the properties listed as follow:
Color By Height: determine color of each vertex by its height.
Color By Normal: determine color of each vertex by its normal vector.
Color Blend Fraction: a fraction to blend between Color By Height and Color By Normal, where alpha=0 is fully by height, and alpha=1 is fully by normal.
Underground Color: color of the underground part.
Flat Shading: toggle between flat and smooth shading, the number of vertices will be tripled when turning on.
Vertex Color: should it generate vertex color? Uncheck if you use a diffuse map for its material.
Solid Face Color: if turn on, vertex color will not be blended across the triangle.
Reduce Surface Noise: Use bilinear instead of point filter when sampling height map.