Plateau

A flat or gently sloping surface, cut by valleys and situated at a certain altitude above sea level. In the Iberian Peninsula, it constitutes the fundamental unit of relief. It is the remnant of an ancient massif that arose during the Hercynian orogeny (Paleozoic), eroded and deformed during the Alpine orogeny, which gave rise to the interior mountain ranges (Central System and Montes de Toledo), the interior sedimentary basins of the northern and southern sub-plateaus, and the mountain ranges (Galician Massif, Cantabrian Mountains, Iberian System, and Sierra Morena).