Madeira is a Portuguese island, and is the largest and most populous of the

Madeira Archipelago ) , anthem = ( en, "Anthem of the Autonomous Region of Madeira") , song_type = Regional anthem , image_map=EU-Portugal_with_Madeira_circled.svg , map_alt=Location of Madeira , map_caption=Location of Madeira , subdivision_type=Sovereign st ...

. It has an area of , including Ilhéu de Agostinho, Ilhéu de São Lourenço, Ilhéu Mole (northwest). As of 2011, Madeira had a total population of 262,456. The island is the top of a massive submerged shield volcano that rises about from the floor of the Atlantic Ocean. The volcano formed atop an east–west rift in the

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic ...

along the African Plate, beginning during the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

epoch over 5 million years ago, continuing into the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

until about 700,000 years ago. This was followed by extensive

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...

, 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. Madeira is the largest island of the group with an area of , a length of (from Ponta de São Lourenço to Ponta do Pargo), while approximately at its widest point (from Ponta da Cruz to Ponta de São Jorge), with a coastline of . It has a mountain ridge that extends along the centre of the island, reaching at its highest point ( Pico Ruivo), while much lower (below ) along its eastern extent. The primitive volcanic foci responsible for the central mountainous area, consisted of the peaks: Ruivo (), Torres (), Arieiro (), Cidrão (), Cedro (), Casado (), Grande (), Ferreiro (). At the end of this eruptive phase, an island circled by reefs was formed, its marine vestiges are evident in a calcareous layer in the area of Lameiros, in São Vicente (which was later explored for

calcium oxide Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term "'' lime''" connotes calcium-containing inorganic ...

production). Sea cliffs, such as

Cabo Girão Cabo Girão is a lofty sea cliff located along the southern coast of the island of Madeira, in the Portuguese archipelago of Madeira, geographically part of Africa. Cabo Girão is a tourist lookout point, with up to 1800 visitors a day. The locat ...

, valleys and ravines extend from this central spine, making the interior generally inaccessible. Daily life is concentrated in the many villages at the mouths of the ravines, through which the heavy rains of autumn and winter usually travel to the sea.Robert White, 1851, p. 4.

References

{{Authority control Madeira Island Islands of the Autonomous Region of Madeira Polygenetic shield volcanoes Miocene shield volcanoes Pliocene shield volcanoes Pleistocene shield volcanoes Holocene shield volcanoes

See also

References