The Isalo and Makay ruiniform sandstone landscape form a natural barrier in the West South, between the Highlands, the Mahafaly limestone Plateau and the Mozambique Channel.
The Ankaratra chain, along with the Tsiafajavona mountain (2 643m) and the massif of Ibity (2 252m), stand over the central Highlands between the cities of Ambatolampy, Antsirabe and Ambositra. The massif of Ibity is well-known for its great geological diversity, half precious stones (tourmaline, garnet, citrine…) and for its floral, faunal and cultural richness. South of Fianarantsoa, the granitic massif of Andringitra, with its main peak, Peak Boby (2 658m), marks in the South East the end of the Highlands. Its majestic cliffs overlook verdant rich plains.