The Massif Central is much more varied with much more exciting geology and geomorphology than the massifs dealt with so far (Armorica, The Ardennes, The Vosges). As with the other massifs, the core is of Hercynian metamorphic and granitic rocks. A major N-S fault system separates the dominantly granite terrain of Limousin to the west from the more complex terrain of Auvergne to the east. Much younger rocks and structures are incorporated into the massif, especially in the southeast. On the southern flanks of the massif are the Cévennes, ranges formed of lower Palaeozoic rocks deformed by Palaogene (Pyrenean) east-west fold structures. Trapped between these areas and the southern part of the massif itself are the uplifted plateaux of Jurassic limestones of the Grands Causses/Gorges du Tarn area. The whole of the Massif Central was uplifted by “mid-Tertiary” (Alpine) tectonics. A major fault system developed along the eastern margin, separating the massif from the downfaulted Rhône/Saône corridor and in the south from the Cretaceous limestone Ardèche plateau. Similarly, the downfaulted Limagne/Allier and Roanne/Loire depressions were formed in the north (in a way mirroring the Rhine rift valley). The final geological phase, also related to post-Alpine conditions, was the Neogene to Quaternary volcanicity in Auvergne. The Quaternary also had two other impacts: small ice caps in the Sancy, Cantal, Aubrac and Forez areas, and the main drainage incised into bedrock, resulting not only in incised meanders but also in several spectacular gorges and canyons, especially in the south, notably the Gorges du Tarn.