Here you can find a lot of various huge cracked cliff models and example gathering.

Materials use PBR shader which include standard set of textures and additional detalisation textures for normals and albedo.

Triangle counts:

Cracked rock big 1 - 13700 tris

Cracked rock big 2 - 8900 tris

Cracked rock mid 1 - 3400 tris

Cracked rock mid 2 - 3750 tris

Cracked rock small 1 - 580 tris

Cracked rock small 2 - 2200 tris

Cracked rock small 3 - 2900 tris

Cracked rock small 4 - 2080 tris

Cracked rock small 5 - 1450 tris

Cracked rock small 6 - 3800 tris

Cracked rock flat 1 - 2900 tris

Cracked rock flat 2 - 2200 tris