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27-574: Cadamosto Seamount lies about 25 kilometres (16 mi) southwest of the island of Brava in the Cape Verde islands and within the Cabo Verde exclusive economic zone . Its name refers to Alvise Cadamosto , who discovered the Cape Verde islands in 1456. The seamount is c. 15 kilometres (9.3 mi) wide at its foot and partially overlaps with Brava. Cadamosto and Brava may be part of

54-449: A viscous fluid . Partial melting of the mantle at mid-ocean ridges produces oceanic crust , and partial melting of the mantle at subduction zones produces continental crust . Mercury has a silicate mantle approximately 490 kilometers (300 miles) thick, constituting only 28% of its mass. Venus 's silicate mantle is approximately 2,800 kilometers (1,700 miles) thick, constituting around 70% of its mass. Mars 's silicate mantle

81-403: A larger northeast-southwest trending alignment of volcanoes. It rises from a depth of 4,000 metres (13,000 ft) to about 1,380 metres (4,530 ft) depth and has a summit with three separate, well-preserved volcanic centres. Sediment cover is sparse and there is evidence of hydrothermal alteration and of recent activity in the form of spatter deposits. Agglutinates and lavas form most of

108-457: A more intense seismic activity occurs at Brava , where it appears to correlate with eruptions on Fogo, and at Cadamosto Seamount which appears to have a different magma source. Based on plate motion models, the Cape Verde hotspot is expected to move southwestward, in the direction of Cadamosto Seamount, and may currently underlie Brava, Fogo and Cadamosto. Apart from Cadamosto Seamount, Nola and Sodade Seamounts are also seismically active. Unlike

135-519: Is Nova Sintra . The island's two parishes São João Baptista and Nossa Senhora do Monte are subdivided into 16 population zones for statistical purposes: São João Baptista Nossa Senhora do Monte In the 1830s, the population was estimated at 8,000. The economy of the island is mainly based on (irrigated) agriculture and fishing. Main agricultural goods include coffee, potatoes including sweet potatoes, corn (maize), banana and sugar cane. There are several football clubs on Boa Vista, organised in

162-463: Is an island in Cape Verde , and is part of the Sotavento group, in the central Atlantic Ocean. At 62.5 km (24.1 sq mi), it is the smallest inhabited island of the Cape Verde archipelago, but at the same time the greenest. First settled in the early 16th century, its population grew after Mount Fogo on neighbouring Fogo erupted in 1680. For more than a century, its main industry

189-463: Is approximately 1,600 kilometers (990 miles) thick, constituting ~74–88% of its mass, and may be represented by chassignite meteorites. Uranus and Neptune 's ice mantles are approximately 30,000 km thick, composing 80% of both masses. Jupiter 's moons Io , Europa , and Ganymede have silicate mantles; Io's ~1,100 kilometers (680 miles) silicate mantle is overlain by a volcanic crust, Ganymede's ~1,315 kilometers (817 miles) thick silicate mantle

216-597: Is overlain by ~835 kilometers (519 miles) of ice, and Europa's ~1,165 kilometers (724 miles) km silicate mantle is overlain by ~85 kilometers (53 miles) of ice and possibly liquid water. The silicate mantle of the Earth's moon is approximately 1300–1400 km thick, and is the source of mare basalts . The lunar mantle might be exposed in the South Pole-Aitken basin or the Crisium basin . The lunar mantle contains

243-498: The Brava Regional Football Association . The Esperadinha Airport , inaugurated in 1992, was closed in 2004 because of persisting strong winds. The village of Furna has a commercial port, the other port is Fajã de Água which is only used for fishing. Ferries to the islands of Fogo and Santiago depart from Furna. On Brava the villages may be reached by "Aluguer" bus. There is no fixed schedule, as

270-467: The Cape Verde Rise , a 130-to-150-million-year-old sector of seafloor covered by a 2-kilometre (1.2 mi) high volcanic plateau. The Rise is associated with a geoid anomaly and may have formed through the activity of a mantle plume / hotspot . On some islands, Jurassic seafloor is exposed. The Cape Verde hotspot is responsible for volcanic activity in the Cape Verde islands. Owing to

297-488: The giant planets , specifically ice giants , a number of asteroids , and some planetary moons have mantles. The Earth's mantle is a layer of silicate rock between the crust and the outer core . Its mass of 4.01 × 10 kg is 67% the mass of the Earth. It has a thickness of 2,900 kilometres (1,800 mi) making up about 84% of Earth's volume. It is predominantly solid, but in geological time it behaves as

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324-435: The last glacial maximum when sea levels were lower. Despite its great depth, Cadamosto Seamount appears to be capable of large explosive eruptions . Tephra layers attributed to Cadamosto Seamount are about 40,000 and 17,000 years old. These eruptions produced a minimum volume of 0.12 cubic kilometres (0.029 cu mi) and 0.21 cubic kilometres (0.050 cu mi) tephra , respectively, equivalent of category 4 on

351-594: The volcanic explosivity index . The eruptions dispersed volcanic ash over areas of 3,100 square kilometres (1,200 sq mi) and 3,850 square kilometres (1,490 sq mi), respectively, through submarine volcanic ash plumes . There is no indication of historical activity but Cadamosto Seamount is the most seismically active seamount on the Cape Verde Rise. During the 21st century, earthquakes with intensities of over mb 4 have been recorded at Cadamosto Seamount. The seismic activity may be related to

378-625: The Azores and the Cape Verde Islands. They used the harbours of Brava ( Fajã de Água and Furna ) to stock up on supplies and drinking water. They hired men from Brava as sailors, and several of these men from Brava settled around the Massachusetts whaling port of New Bedford . The island of Brava is 10.5 km long (north to south) and its width is 9.3 km. Its area is 62.51 km (24.14 sq mi). Practically

405-427: The alteration of volcanic rocks by seawater. The genesis of the magmas erupted by Cadamosto Seamount involves the ascent of mantle melts into the crust , where storage and clinopyroxene crystallization take place. Only small amounts of crustal material and sediments are absorbed by the ascending magma, but mixing of the felsic magma with more mafic one has been inferred from dredged volcanic rocks. The formation of

432-493: The aluguers travel only when there are sufficient passengers. A few taxis are available as well. Mantle (geology) A mantle is a layer inside a planetary body bounded below by a core and above by a crust . Mantles are made of rock or ices , and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone differentiation by density . All terrestrial planets (including Earth ), half of

459-657: The coast and semi-arid mild tropical climate BSh with very balanced temperatures year round in the interior. The average annual temperature on the coast is about 23–25 °C (73–77 °F), decreasing to some 17–20 °C (63–68 °F) in the mountains. There can be remarkably cool weather with warmer wet season starting in June and ending in November with colder dry season starting in December and ending in May. Administratively,

486-506: The island of Brava is covered by one municipality, Concelho da Brava . This municipality consists of two freguesias (civil parishes): São João Baptista and Nossa Senhora do Monte . The municipal seat is the city Nova Sintra . Since 2012, the Movement for Democracy (MpD) is the ruling party of the municipality, and its president is Orlando da Luz Vieira Balla. The results of the latest elections, in 2016 : The island's main town

513-485: The movement of magma in dykes , a magmatic system spanning Cadamosto, Brava and Fogo, and to a normal fault system between Brava and Cadamosto Seamount. The volcanic activity at Cadamosto Seamount may presage the future formation of a new island there. This might take up to 100,000 years. Coral gardens and sponges grow on Cadamosto Seamount and are populated by crabs , fish and other animals. Brava, Cape Verde Brava ( Portuguese for "wild" or "brave")

540-436: The nearby larger island of Fogo after its volcano erupted and covered the island with ash. Frequent pirate attacks forced the population towards the interior of the island, where the town Nova Sintra was founded around 1700. Around 1720, the fungus Roccella tinctoria was discovered, which was traded as a textile dye. From the end of the 18th century, whaling ships from North America started hunting whales around

567-435: The phonolitic magma might take place within large magma chambers . Ages of crystals found in dredge samples indicate that the magmatic system of Cadamosto Seamount is about 1.52 million years old. Dredged rocks themselves have yielded ages of 97,000 ± 14,000, 51,800 ± 2,400 and 21,140 ± 620 years by argon-argon dating . Volcanic activity appears to have been influenced by sea level variations, with eruptions occurring during

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594-553: The rest of the Cape Verde islands which have mainly erupted mafic rocks, Cadamosto Seamount and Brava feature felsic rocks. The dominant volcanic rock is phonolite and phonotephrite although clinopyroxene nephelinite has also been recorded. Volcanic samples dredged from Cadamosto Seamount contain crystals of aegirine , apatite , augite , biotite , diopside , haüyne , iron-titanium oxides , leucite , nepheline , nosean , pyrite , sanidine , sodalite and titanite . Calcite , clay and iron oxyhydroxides formed through

621-482: The seamount, with sheet and pillow lavas cropping out in the summit region, some hydrothermally altered. Numerous craters and small volcanic cones dot its flanks which bear evidence of sector collapses . The Cape Verde islands lie about 500 kilometres (310 mi) west of Senegal and feature nine main islands, as well as a number of islets and seamounts . Unusually for a hotspot volcanic system, Cape Verde has two separate chains of volcanoes. The islands lie on

648-639: The slow movement of the African Plate , there is only little evidence of migrating volcanism. It appears that the oldest volcanism occurred 16–12 million years ago at Maio and Sal , while activity in the last 500,000 years has been concentrated at Fogo and Santo Antao at the western end of the Cape Verde islands. Of these, Fogo has displayed the most recent activity with eruptions during historical time such as in 1769, 1785, 1799, 1847, 1853, 1857, 1951, 1995 and 2014/2015, and marine records show evidence of past sub-Plinian and Plinian eruptions . However,

675-443: The whole island is a stratovolcano . It lies in the lee of the enormous Fogo volcano. Volcanic activity on the island has been mainly located along three lines, which all intersect at the crest of ground that forms the highest part of the island. Brava has no documented historical eruptions, but its youthful volcanic morphology and the fact that earthquake swarms still occur indicate the potential for future eruptions; its last eruption

702-603: Was whaling , but the island economy is now primarily agricultural . Brava was discovered in 1462 by the Portuguese explorer Diogo Afonso . There is no evidence of human presence on the Cape Verde islands before the arrival of the Portuguese. Around 1620 the population of Brava started with the arrival of settlers from Madeira and the Azores . Settlement of Brava took a rise in 1680 when it received many refugees from

729-496: Was during the Holocene era. 13% of the island area is forested. North of Brava are several uninhabited islets; the largest ones are Ilhéu de Cima and Ilhéu Grande . Monte Fontainhas is the highest point on the island, reaching 976 metres elevation. Being highly mountainous this island has a quite diverse climate. Brava island has moderate arid climate ( BWh according to Köppen–Geiger climate classification system) along

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