Madeira Island

Madeira is a Portuguese island, and is the largest and most populous of the Madeira Archipelago. It has an area of 740.7 km (286 sq mi), including Ilhéu de Agostinho, Ilhéu de São Lourenço, Ilhéu Mole (northwest). As of 2021, Madeira had a total population of 245,595.

The island is the top of a massive submerged shield volcano that rises about six kilometres (20,000 ft) from the floor of the Atlantic Ocean. The volcano formed atop an east–west rift in the oceanic crust along the African Plate, beginning during the Miocene epoch over five million years ago, continuing into the Pleistocene until about 700,000 years ago. This was followed by extensive erosion, producing two large amphitheatres open to south in the central part of the island. Volcanic activity later resumed, producing scoria cones and lava flows atop the older eroded shield. The most recent volcanic eruptions were on the west-central part of the island only 6,500 years ago, creating more cinder cones and lava flows.