The volcanism which gave birth to the Estérel massif with its characteristic red rocks plunging into the sea is linked to a Permian extension of the earth's crust. It was marked by the bursting of Pangea, the ultracontinent formed in the Carboniferous period that linked France to Africa and America, and the formation of Tethys, the paleo-ocean that opened up during the Paleozoic. Such extension volcanism is also visible in Corsica at Monte Cinto and in Morvan at Montreuillon.