The Paris Basin is one of the major geological regions of France having developed since the Triassic on a basement formed by the Variscan orogeny. The sedimentary basin is a large sag in the craton, bordered by the Armorican Massif to the west, the Ardennes-Brabant axis to the north, the Massif des Vosges to the east, and the Massif Central to the south.