The Pyrenean zone was created in late Cretaceous to Eocene time, by the rotation of the Iberian platelet from its previous location in the Bay of Biscay area, then its northward movement and collision with the European plate. The main structural deformation occurred during the Eocene forming a narrow west to east mountain belt, the Pyrenees, along the Franco-Spanish border. Although the main structural deformation took place during the Eocene, major post-orogenic uplift continued well into the Miocene. There are three zones to the mountain belt aligned E-W. To the north of the mountains in the central zone is a n enormous Miocene megafan. East and west of the fan is a belt of dominantly Cretaceous folded sedimentary rocks across which the predominantly S-N drainage is transverse. South of this belt are the mountains themselves exhibiting both Pleistocene glaciated terrain and small modern glaciers.