Playing around, I stuck a blend node on the Result Scale of a simple Voronoi monofractal and blended two mountain heights(16,000m and 18,000m say )with a mirrored u-shaped curve. Editing the curve can make the ridges wider and increasing the mountain height difference will make the cuts deeper.You can download a three world file.zip at http://www.aktati.planetisp.co.uk/Downloads/Rendostudy.zip