The Col du Mône is located on a fault line that separates two different geological formations: the Mône rock which is a formation of limestones and dolomitic stones from the Jurassic whose stratigraphic series is reversed, and the Petit Mont-Blanc which is formed of gypsum, a very white rock. On the Mône rock, the rocks are rather grey, formed in layers with a reddish layer of bauxite, a rock rich in aluminium and iron oxide. The Petit Mont-Blanc looks like a lunar landscape with its white, globe-shaped rocks.