Madeira is a Portuguese island, and is the largest and most populous of the Madeira Archipelago. It has an area of , 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 A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...

that rises about from the floor of the Atlantic Ocean. The volcano formed atop an east–west

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...

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 ultramaf ...

along the African Plate, beginning during the

Miocene The Miocene ( ) is the first epoch (geology), 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 mea ...

epoch over 5 million years ago, continuing into the

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

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

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

, producing two large amphitheatres open to south in the central part of the island. Volcanic activity later resumed, producing

scoria cone A cinder cone or scoria cone is a steep, conical landform of loose pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions or l ...

s and

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

s 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 cone A cinder cone or scoria cone is a steep, volcanic cone, conical landform of loose pyroclastic rock, pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are forme ...

s 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 Pico Ruivo () is the highest peak on Madeira Island and the third highest in Portugal, standing at in the Santana municipality. Accessible only by foot, it can be reached from either Pico do Areeiro or via a shorter, easier trail from Achada ...

), 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 (formula: Ca O), 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 ...

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 lo ...

, 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