By the early Cenozoic, the ocean retreated, except in the Casamance Gulf and by the Eocene, the region was experiencing intense, terrestrial weathering. The Cap-Vert experienced two peaks of volcanism, one in the Miocene and the other in the Quaternary, producing small occurrences of understaturated, alkaline lavas. During the Quaternary, volcanism at the head of the Cap-Vert peninsula built the Mamelles volcano and its associated vents and flows.