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168-637: The Cameroon volcanic line is geologically unusual in extending through both the ocean and the continental crust. Various hypotheses have been advanced by different geologists to explain the line. In the Gulf of Guinea, the Cameroon line consists of six offshore volcanic swells that have formed islands or seamounts . From the southwest to the northeast the island groups are Annobón (or Pagalu), São Tomé , Príncipe and Bioko . Two large seamounts lie between São Tomé and Príncipe, and between Príncipe and Bioko. On

336-415: A commensal relationship , for example brittle stars , who climb the coral to get themselves off the seafloor, helping them to catch food particles, or small zooplankton, as they drift by. This is in sharp contrast with the typical deep-sea habitat, where deposit-feeding animals rely on food they get off the ground. In tropical zones extensive coral growth results in the formation of coral atolls late in

504-549: A megacity like Lagos and other major Nigerian cities which are linked with economic development, population growth and the inability of municipal councils to manage the resulting rise in industrial and domestic waste. This waste management problem is also attributable to unsustainable environmental management lifestyles of Kubwa community in the Federal Capital Territory, where there are habits of indiscriminate disposal of waste, dumping of waste along or into

672-399: A certain pattern in terms of eruptive activity, first observed with Hawaiian seamounts but now shown to be the process followed by all seamounts of the ocean-ridge type. During the first stage the volcano erupts basalt of various types, caused by various degrees of mantle melting . In the second, most active stage of its life, ocean-ridge volcanoes erupt tholeiitic to mildly alkalic basalt as

840-471: A civilian government but not before appointing Ernest Shonekan head of an interim national government . Babangida's regime has been considered the most corrupt and responsible for creating a culture of corruption in Nigeria. Shonekan's interim government, the shortest in the political history of the country, was overthrown in a coup d'état of 1993 led by General Sani Abacha , who used military force on

1008-720: A classic example being the Emperor Seamounts , an extension of the Hawaiian Islands . Formed millions of years ago by volcanism , they have since subsided far below sea level. This long chain of islands and seamounts extends thousands of kilometers northwest from the island of Hawaii . There are more seamounts in the Pacific Ocean than in the Atlantic, and their distribution can be described as comprising several elongate chains of seamounts superimposed on

1176-515: A cloud of carbon dioxide gas that killed at least 1,200 people. The region has cool temperatures, heavy rainfall, and savanna vegetation. The plateau experiences an equatorial climate with a wet season of nine months, and a dry season of three months. During the wet season, humid, prevailing monsoon winds blow in from the west and lose their moisture upon hitting the region's mountains. Average rainfall per year ranges from 1,000 mm (39 in) to 2,000 mm (79 in). High elevations give

1344-437: A daunting task due to their sheer number. The most detailed seamount mappings are provided by multibeam echosounding ( sonar ), however after more than 5000 publicly held cruises, the amount of the sea floor that has been mapped remains minuscule. Satellite altimetry is a broader alternative, albeit not as detailed, with 13,000 catalogued seamounts; however this is still only a fraction of the total 100,000. The reason for this

1512-469: A defence against brush fires and dry weather. Raffia palms grow in the valleys and depressions. Geologists disagree over which volcanic regions should be included in the Cameroon volcanic line. All definitions include the islands and the continental stretch up to Oku. Based on similarities in age and composition, some also include the Ngaoundere Plateau , which extends the line to the east in

1680-440: A few Forro speakers. Bioko is just 32 km (20 mi) off the coast of Cameroon , on the continental shelf. The island used to be the end of a peninsula attached to the mainland, but was cut off when sea levels rose 10,000 years ago at the end of the last last glaciation . With an area of 2,017 km (779 sq mi) it is the largest island in the Cameroon line. Bioko has three basaltic shield volcanoes, joining at

1848-507: A few have been studied in detail by scientists. Seamounts and guyots are most abundant in the North Pacific Ocean, and follow a distinctive evolutionary pattern of eruption, build-up, subsidence and erosion. In recent years, several active seamounts have been observed, for example Kamaʻehuakanaloa (formerly Lōʻihi) in the Hawaiian Islands . Because of their abundance, seamounts are one of the most common marine ecosystems in

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2016-516: A formally independent federation on 1 October 1960. It experienced a civil war from 1967 to 1970, followed by a succession of military dictatorships and democratically elected civilian governments until achieving a stable government in the 1999 Nigerian presidential election , with the election of Olusegun Obasanjo of the Peoples Democratic Party . However, the country frequently experiences electoral fraud , and corruption

2184-405: A global understanding of seamount ecosystems, and the roles they have in the biogeography , biodiversity , productivity and evolution of marine organisms. Possibly the best ecologically studied seamount in the world is Davidson Seamount , with six major expeditions recording over 60,000 species observations. The contrast between the seamount and the surrounding area was well-marked. One of

2352-651: A more or less random background distribution. Seamount chains occur in all three major ocean basins, with the Pacific having the most number and most extensive seamount chains. These include the Hawaiian (Emperor), Mariana, Gilbert, Tuomotu and Austral Seamounts (and island groups) in the north Pacific and the Louisville and Sala y Gomez ridges in the southern Pacific Ocean. In the North Atlantic Ocean,

2520-468: A number of seamounts are active undersea volcanoes; two examples are Kamaʻehuakanaloa (formerly Lo‘ihi) in the Hawaiian Islands and Vailulu'u in the Manu'a Group ( Samoa ). The most apparent lava flows at a seamount are the eruptive flows that cover their flanks, however igneous intrusions , in the forms of dikes and sills , are also an important part of seamount growth. The most common type of flow

2688-420: A particular pattern of growth, activity, subsidence and eventual extinction. The first stage of a seamount's evolution is its early activity, building its flanks and core up from the sea floor. This is followed by a period of intense volcanism, during which the new volcano erupts almost all (e.g. 98%) of its total magmatic volume. The seamount may even grow above sea level to become an oceanic island (for example,

2856-429: A result of a larger area melting in the mantle. This is finally capped by alkalic flows late in its eruptive history, as the link between the seamount and its source of volcanism is cut by crustal movement. Some seamounts also experience a brief "rejuvenated" period after a hiatus of 1.5 to 10 million years, the flows of which are highly alkalic and produce many xenoliths . In recent years, geologists have confirmed that

3024-432: A river system. The river system of the northeast is also a major river system. In addition, Nigeria has numerous coastal rivers. Over the last million years, Lake Chad in the far north-east of Nigeria has dried up several times for a few thousand years and just as often growing to many times its current size. In recent decades its surface area has been reduced considerably, which may also be due to humans taking water from

3192-559: A successful jihad against the Hausa Kingdoms , founding the centralised Sokoto Caliphate . This empire, with Arabic as its official language, grew rapidly under his rule and that of his descendants , who sent out invading armies in every direction. The vast landlocked empire connected the east with the western Sudan region and made inroads down south conquering parts of the Oyo Empire (modern-day Kwara ), and advanced towards

3360-460: A summit collapse on the northern edge of Vlinder Seamount resulted in a pronounced headwall scarp and a field of debris up to 6 km (4 mi) away. A catastrophic collapse at Detroit Seamount flattened its whole structure extensively. Lastly, in 2004, scientists found marine fossils 61 m (200 ft) up the flank of Kohala mountain in Hawaii . Subsidation analysis found that at

3528-572: A triumvirate of three brigadier generals whose decisions could be vetoed by a Supreme Military Council . For this triumvirate, they convinced General Murtala Muhammed to become military head of state, with General Olusegun Obasanjo as his second-in-command, and General Theophilus Danjuma as the third. Together, the triumvirate introduced austerity measures to stem inflation, established a Corrupt Practices Investigation Bureau, replaced all military governors with new officers, and launched "Operation Deadwood" through which they fired 11,000 officials from

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3696-706: A wide scale to suppress the continuing civilian unrest. In 1995, the government hanged environmentalist Ken Saro-Wiwa on trumped-up charges in the deaths of four Ogoni elders, which caused Nigerian's suspension from the Commonwealth . Lawsuits under the American Alien Tort Statute against Royal Dutch Shell and Brian Anderson, the head of Shell's Nigerian operation, settled out of court with Shell continuing to deny liability. Several hundred million dollars in accounts traced to Abacha were discovered in 1999. The regime came to an end in 1998 when

3864-484: A wide variety of tectonic settings, resulting in a very diverse structural bank. Seamounts come in a wide variety of structural shapes, from conical to flat-topped to complexly shaped. Some are built very large and very low, such as Koko Guyot and Detroit Seamount ; others are built more steeply, such as Kamaʻehuakanaloa Seamount and Bowie Seamount . Some seamounts also have a carbonate or sediment cap . Many seamounts show signs of intrusive activity , which

4032-425: Is Bowie Seamount , which has also been declared a marine protected area by Canada for its ecological richness. The study of seamounts has been hindered for a long time by the lack of technology. Although seamounts have been sampled as far back as the 19th century, their depth and position meant that the technology to explore and sample seamounts in sufficient detail did not exist until the last few decades. Even with

4200-429: Is English , chosen to facilitate linguistic unity at the national level. Nigeria's constitution ensures de jure freedom of religion , and it is home to some of the world's largest Muslim and Christian populations. Nigeria is divided roughly in half between Muslims , who live mostly in the north part of the country, and Christians , who live mostly in the south; indigenous religions , such as those native to

4368-418: Is Portuguese , but there are many speakers of Forro and Angolar (Ngola), two Portuguese-based creole languages . The economy is mainly based on tourism. Agriculture is important near the north and east coasts, with the chief exports being cocoa , coffee , copra , and palm products. There are large reserves of oil in the ocean between Nigeria and São Tomé which have not yet been exploited. Príncipe

4536-413: Is pillow lava , named so after its distinctive shape. Less common are sheet flows, which are glassy and marginal, and indicative of larger-scale flows. Volcaniclastic sedimentary rocks dominate shallow-water seamounts. They are the products of the explosive activity of seamounts that are near the water's surface, and can also form from mechanical wear of existing volcanic rock. Seamounts can form in

4704-426: Is a part of Equatorial Guinea . The island has a population of 334,463 inhabitants (2015 Census), most of whom are Bubi . The rest of the population are Fernandinos , Spaniards and immigrants from Río Muni , Nigeria and Cameroon . Cocoa production was once the main export, but has declined in recent years. Farming, fishing and logging remain important. Natural gas is produced in offshore wells, processed on

4872-551: Is considered to be the foundation of Igbo culture . Nri and Aguleri , where the Igbo creation myth originates, are in the territory of the Umeuri clan. Members of the clan trace their lineages back to the patriarchal king-figure Eri . In West Africa, the oldest bronzes made using the lost wax process were from Igbo-Ukwu , a city under Nri influence. The Yoruba kingdoms of Ife and Oyo in southwestern Nigeria became prominent in

5040-511: Is disputed by scientists who point out that features of the region are quite different from what is predicted by that hypothesis, and that a source in a lithospheric fracture is more likely to be the explanation. One explanation for the origin of the volcanic line is likely leakage of magma from reactivated Precambrian faults, while another scenario is the rising of mantle material from African Large low-shear-velocity provinces travels under Congo Craton and through existing fractures ultimately feed

5208-582: Is evidence that a mantle plume has existed in the region for about 140 million years, first remaining in roughly the same position while the African plate rotated above it, and then remaining stationary under the Oku area since around 66 million years ago. In this theory, the abnormal heat rising in a mantle plume would lead to melting of the upper mantle , which raises, thins and weakens the crust and facilitates rifting. This may have been repeated several times in

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5376-497: Is greatest as a proportion of seafloor area in the North Pacific Ocean, equal to 4.39% of that ocean region. The Arctic Ocean has only 16 seamounts and no guyots, and the Mediterranean and Black seas together have only 23 seamounts and 2 guyots. The 9,951 seamounts which have been mapped cover an area of 8,088,550 km (3,123,010 sq mi). Seamounts have an average area of 790 km (310 sq mi), with

5544-490: Is helped by geochemical exchange between the seamounts and the ocean water. Seamounts may thus be vital stopping points for some migratory animals , specifically whales . Some recent research indicates whales may use such features as navigational aids throughout their migration. For a long time it has been surmised that many pelagic animals visit seamounts as well, to gather food, but proof of this aggregating effect has been lacking. The first demonstration of this conjecture

5712-406: Is hurt by the simple lack of information available. Seamounts are very poorly studied, with only 350 of the estimated 100,000 seamounts in the world having received sampling, and fewer than 100 in depth. Much of this lack of information can be attributed to a lack of technology, and to the daunting task of reaching these underwater structures; the technology to fully explore them has only been around

5880-604: Is likely to lead to inflation , steepening of volcanic slopes, and ultimately, flank collapse. There are also several sub-classes of seamounts. The first are guyots , seamounts with a flat top. These tops must be 200 m (656 ft) or more below the surface of the sea; the diameters of these flat summits can be over 10 km (6.2 mi). Knolls are isolated elevation spikes measuring less than 1,000 meters (3,281 ft). Lastly, pinnacles are small pillar-like seamounts. Seamounts are exceptionally important to their biome ecologically, but their role in their environment

6048-401: Is named after the ship that struck it in 1973. However, the greatest danger from seamounts are flank collapses; as they get older, extrusions seeping in the seamounts put pressure on their sides, causing landslides that have the potential to generate massive tsunamis . Seamounts can be found in every ocean basin in the world, distributed extremely widely both in space and in age. A seamount

6216-564: Is plains of tall grass interrupted by trees. Sudan savannah is similar but with shorter grasses and shorter trees. Sahel savannah consists of patches of grass and sand, found in the northeast. Nigeria is divided into two main catchment areas - that of Lake Chad and that of the Niger. The Niger catchment area covers about 63% of the country. The main tributary of the Niger is the Benue, whose tributaries extend beyond Cameroon into Cameroon into Chad and

6384-452: Is poorly understood. Because they project out above the surrounding sea floor, they disturb standard water flow, causing eddies and associated hydrological phenomena that ultimately result in water movement in an otherwise still ocean bottom. Currents have been measured at up to 0.9 knots, or 48 centimeters per second. Because of this upwelling seamounts often carry above-average plankton populations, seamounts are thus centers where

6552-460: Is protected by the 330 km (130 sq mi) Basilé National Park and the 510 km (200 sq mi) Luba Crater Scientific Reserve . There has been little habitat loss, and the southern slopes have remained almost completely undisturbed. Although hunting pressure is rising, the fauna in the inaccessible southern part of the island is mostly intact. This includes an endemic subspecies of drill, Mandrillus leucophaeus poensis . Bioko

6720-462: Is rampant in various levels of Nigerian politics. Nigeria is a multinational state inhabited by more than 250 ethnic groups speaking 500 distinct languages , all identifying with a wide variety of cultures. The three largest ethnic groups are the Hausa in the north , Yoruba in the west , and Igbo in the east , together constituting over 60% of the total population. The official language

6888-477: Is responsible for as much as 95% of ecological damage to seamounts. Corals from seamounts are also vulnerable, as they are highly valued for making jewellery and decorative objects. Significant harvests have been produced from seamounts, often leaving coral beds depleted. Individual nations are beginning to note the effect of fishing on seamounts, and the European Commission has agreed to fund

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7056-543: Is technically defined as an isolated rise in elevation of 1,000 m (3,281 ft) or more from the surrounding seafloor, and with a limited summit area, of conical form. There are more than 14,500 seamounts. In addition to seamounts, there are more than 80,000 small knolls , ridges and hills less than 1,000 m in height in the world's oceans. Most seamounts are volcanic in origin, and thus tend to be found on oceanic crust near mid-ocean ridges , mantle plumes , and island arcs . Overall, seamount and guyot coverage

7224-404: Is that often, in the late of stages of their life, extrusions begin to seep in the seamount. This activity leads to inflation, over-extension of the volcano's flanks, and ultimately flank collapse , leading to submarine landslides with the potential to start major tsunamis , which can be among the largest natural disasters in the world. In an illustration of the potent power of flank collapses,

7392-399: Is that the fishes that are targeted over seamounts are typically long-lived, slow-growing, and slow-maturing. The problem is confounded by the dangers of trawling , which damages seamount surface communities, and the fact that many seamounts are located in international waters, making proper monitoring difficult. Bottom trawling in particular is extremely devastating to seamount ecology, and

7560-463: Is that uncertainties in the technology limit recognition to features 1,500 m (4,921 ft) or larger. In the future, technological advances could allow for a larger and more detailed catalogue. Observations from CryoSat-2 combined with data from other satellites has shown thousands of previously uncharted seamounts, with more to come as data is interpreted. Seamounts are a possible future source of economically important metals. Even though

7728-450: Is the smaller of the two major islands of São Tomé and Príncipe , with an area of 136 km (53 sq mi). Volcanic activity stopped around 15.7 million years ago, and the island has been deeply eroded apart from spectacular towers of phonolite . The island is surrounded by smaller islands including Ilheu Bom Bom , Ilhéu Caroço , Tinhosa Grande and Tinhosa Pequena , and lies in ocean 3,000 m (9,800 ft) deep. It rises in

7896-471: Is tropical at lower altitudes, becoming about 1 °C (1.8 °F) cooler for each 150 m (492 ft) of elevation. There is open canopy montane forest above 1,500 m (4,900 ft) on Pico Basilé, Gran Caldera de Luba and Pico Biao, with subalpine grassland above 2,500 m (8,200 ft). Bioko has exceptional numbers of endemic species of flora and fauna, partly due to the great range of altitudes, particularly birdlife. The montane forest

8064-819: Is visible in the Foumban Shear Zone , which was active before and during the opening of the South Atlantic in the Cretaceous period. The western end of the shear zone is obscured by the volcanoes of the Cameroon line, but based on reconstruction of the configuration of South America before it separated from Africa, the Foumban Shear Zone can be identified with the Pernambuco fault in Brazil. A major earthquake in 1986 could indicate that

8232-498: The 2009 eruption of Hunga Tonga ). After a period of explosive activity near the ocean surface , the eruptions slowly die away. With eruptions becoming infrequent and the seamount losing its ability to maintain itself, the volcano starts to erode . After finally becoming extinct (possibly after a brief rejuvenated period), they are ground back down by the waves. Seamounts are built in a far more dynamic oceanic setting than their land counterparts, resulting in horizontal subsidence as

8400-735: The Adamawa Plateau ; the Biu plateau of Nigeria to the north of the Yola arm of the Benue Trough, and the Jos Plateau to the west of the Benue Trough. There are varying theories for the similarities between the oceanic and continental volcanoes. The Cameroon line bisects the angle where the coast of Africa makes a 90° bend from the southern coast along the west of the Congo craton and

8568-502: The Bight of Benin , and Bonny Island on the Bight of Biafra. The majority of those taken to these ports were captured in raids and wars. Usually, the captives were taken back to the conquerors' territory as forced labour ; they were sometimes gradually acculturated and absorbed into the conquerors' society. Slave routes were established throughout Nigeria linking the hinterland areas with

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8736-798: The Bornu Empire gave rise to the British-controlled Borno Emirate which established Abubakar Garbai of Borno as ruler. In 1903, the British victory in the Battle of Kano gave them a logistical edge in pacifying the heartland of the Sokoto Caliphate and parts of the former Bornu Empire. On 13 March 1903, at the grand market square of Sokoto, the last vizier of the caliphate officially conceded to British rule. The British appointed Muhammadu Attahiru II as

8904-666: The Eastern Region . In May 1967, Governor of the Eastern Region Lt. Colonel Emeka Ojukwu declared the region independent from the federation as a state called the Republic of Biafra , as a result of the continuous and systematically planned attacks against Igbos and those of Eastern extraction popularly known as 1966 pogroms . This declaration precipitated the Nigerian Civil War , which began as

9072-760: The Federal Republic of Nigeria , is a country in West Africa . It is situated between the Sahel to the north and the Gulf of Guinea to the south in the Atlantic Ocean . It covers an area of 923,769 square kilometres (356,669 sq mi). With a population of more than 230 million, it is the most populous country in Africa , and the world's sixth-most populous country . Nigeria borders Niger in

9240-582: The Igbo and Yoruba ethnicities, are in the minority. Nigeria is a regional power in Africa and a middle power in international affairs. Nigeria's economy is the fourth-largest in Africa , the 53rd-largest in the world by nominal GDP , and 27th-largest by PPP . Nigeria is often referred to as the Giant of Africa owing to its large population and economy , and is considered to be an emerging market by

9408-669: The Lagos Treaty of Cession . British missionaries expanded their operations and travelled further inland. In 1864, Samuel Ajayi Crowther became the first African bishop of the Anglican Church . In 1885, British claims to a West African sphere of influence received recognition from other European nations at the Berlin Conference . The following year, it chartered the Royal Niger Company under

9576-571: The Muslim world . There are early historical references by medieval Arab and Muslim historians and geographers which refer to the Kanem–Bornu Empire as the region's major centre for Islamic civilization. The Kingdom of Nri of the Igbo people consolidated in the 10th century and continued until it lost its sovereignty to the British in 1911. Nri was ruled by the Eze Nri , and the city of Nri

9744-761: The New England Seamounts extend from the eastern coast of the United States to the mid-ocean ridge. Craig and Sandwell noted that clusters of larger Atlantic seamounts tend to be associated with other evidence of hotspot activity, such as on the Walvis Ridge , Vitória-Trindade Ridge , Bermuda Islands and Cape Verde Islands . The mid-Atlantic ridge and spreading ridges in the Indian Ocean are also associated with abundant seamounts. Otherwise, seamounts tend not to form distinctive chains in

9912-589: The Niger River running through the country. This name was coined on 8 January 1897, by the British journalist Flora Shaw . The neighboring Republic of Niger takes its name from the same river. The origin of the name Niger , which originally applied to only the middle reaches of the Niger River, is uncertain. The word is likely an alteration of the Tuareg name egerew n-iger ewen used by inhabitants along

10080-564: The Nigerian Political Bureau which made recommendations for the transition to the Third Nigerian Republic. In 1989, Babangida started making plans for the transition to the Third Nigerian Republic. Babangida survived the 1990 Nigerian coup d'état attempt , then postponed a promised return to democracy to 1992. Babangida legalized the formation of political parties and formed the two-party system with

10248-602: The Northern Nigeria Protectorate into the Colony and Protectorate of Nigeria . Administratively, Nigeria remained divided into the Northern and Southern Protectorates and Lagos Colony . Inhabitants of the southern region sustained more interaction, economic and cultural, with the British and other Europeans owing to the coastal economy. Christian missions established Western educational institutions in

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10416-450: The Pico de São Tomé . The oldest rock on São Tomé is 13 million years old. Most of the lava that has erupted over the last million years has been basalt . The youngest dated rock on the island is about 100,000 years old, but numerous more recent cinder cones are found on the southeast side of the island. Due to the prevailing southwesterly winds, there is great variability in rainfall. In

10584-548: The Santonian age, around 84 million years ago, the Benue Trough underwent intense compression and folding. Since then it has been tectonically quiet. The basaltic rocks in the oceanic and continental sectors of the Cameroon line are similar in composition, although the more evolved rocks are quite distinct. The similarity in basaltic rocks may indicate they have the same source. Since the lithosphere mantle below Africa must be different in chemical and isotopic composition from

10752-560: The Social Democratic Party and National Republican Convention ahead of the 1992 general elections . He urged all Nigerians to join either of the parties, which Chief Bola Ige referred to as "two leper hands". The 1993 presidential election held on 12 June was the first since the military coup of 1983. The results, though not officially declared by the National Electoral Commission, showed

10920-800: The World Bank . Nigeria is a founding member of the African Union and a member of many international organizations, including the United Nations , the Commonwealth of Nations , NAM , the Economic Community of West African States , Organisation of Islamic Cooperation and OPEC . It is also a member of the informal MINT group of countries and is one of the Next Eleven economies. The name Nigeria derives from

11088-525: The Yoruba heartland of Ibadan , to reach the Atlantic Ocean. The territory controlled by the empire included much of modern-day northern and central Nigeria. The sultan sent out emirs to establish suzerainty over the conquered territories and promote Islamic civilization; the emirs in turn became increasingly rich and powerful through trade and slavery. By the 1890s, the largest slave population in

11256-451: The orange roughy ( Hoplostethus atlanticus ). 95% of ecological damage is done by bottom trawling , which scrapes whole ecosystems off seamounts. Because of their large numbers, many seamounts remain to be properly studied, and even mapped. Bathymetry and satellite altimetry are two technologies working to close the gap. There have been instances where naval vessels have collided with uncharted seamounts; for example, Muirfield Seamount

11424-576: The 10th century. With the spread of Islam from the 7th century AD, the area became known as Sudan or as Bilad Al Sudan (English: Land of the Blacks). Since the populations were partially affiliated with the Arab Muslim culture of North Africa , they began trans-Saharan trade and were referred to by the Arabic speakers as Al-Sudan (meaning "The Blacks") as they were considered an extended part of

11592-467: The 12th and 14th centuries, respectively. The oldest signs of human settlement at Ife's current site date back to the 9th century, and its material culture includes terracotta and bronze figures. In the 16th century, Portuguese explorers were the first Europeans to begin important, direct trade with the peoples of southern Nigeria, at the port they named Lagos (formerly Eko) and in Calabar along

11760-586: The 2007 general elections, Umaru Yar'Adua of the People's Democratic Party came to power. The international community, which had observed the Nigerian elections to promote a free and fair process, condemned these elections as seriously flawed. Yar'Adua died on 5 May 2010, and Vice President Goodluck Jonathan had been sworn in by the Senate three months earlier as acting president to succeed Yar'Adua. Jonathan won

11928-449: The 2011 presidential election; the polls went smoothly and with relatively little violence or electoral fraud. Jonathan's tenure saw an economic recovery that made Nigeria the leading economic power in Africa. The Jonathan administration also saw an increase in unparalleled corruption, with as many as 20 billion US dollars said to have been lost to the Nigerian state through the national oil company. Above all, however, Jonathan's tenure saw

12096-713: The Bamboutos Mountains and becomes the Cross River on its lower course, and the Nkam , which is known as the Wouri River on its lower course. The region gives rise to important tributaries to the Sanaga River . These rivers have a long high-water period during the wet season and a short low-water period during the dry season. Volcanism has created fertile black and brown soils. The Western High Plateau

12264-472: The Benue Trough between 140 Ma and 49 Ma. One plume-related hypothesis for the later development of the Cameroon Line around 30 Ma is that it coincides with development of a shallow mantle convection system centered on the mantle plume, and is related to thinning and extension of the crust along the Cameroon line as pressures relaxed in the now stationary plate. The traditional mantle plume hypothesis

12432-467: The British government moved Nigeria toward self-government on a representative and increasingly federal basis. By the eve of independence in 1960, regional differences in modern educational access were marked. The legacy, though less pronounced, continues to the present day. The balance between north and south was also expressed in Nigeria's political life. For instance, northern Nigeria did not outlaw slavery until 1936 whilst in other parts of Nigeria, slavery

12600-763: The Chad Basin, where the course of the El Beid River forms the border with Cameroon, from the Mandara Mountains to Lake Chad. The Komadugu Yobe river system gives rise to the internationally important Hadejia-Nguru wetlands and Ox-bow lakes around Lake Nguru in the rainy season. Other rivers of the northeast include the Ngadda and the Yedseram, both of which flow through the Sambisa swamps, thus forming

12768-479: The Indian and Southern Oceans, but rather their distribution appears to be more or less random. Isolated seamounts and those without clear volcanic origins are less common; examples include Bollons Seamount , Eratosthenes Seamount , Axial Seamount and Gorringe Ridge . If all known seamounts were collected into one area, they would make a landform the size of Europe . Their overall abundance makes them one of

12936-590: The Kwankwassiya of Rabiu Kwankwaso , former governor of Kano State in the Northwest. Bola Tinubu , of the ruling party, won the disputed election with 36.61% of the vote, but both runners-up claimed victory and litigation is ongoing in an election tribunal. Bola Tinubu's inauguration was held on 29 May 2023. Problems with widespread kidnapping in Nigeria continued. On 29 May 2024, Tinubu signed into law an act readopting Nigeria, We Hail Thee , which

13104-600: The Niger and the Cross Rivers has lost most of its forest because of development and harvesting by increased population and has been replaced by grassland . Everything in between the far south and the far north is savannah (insignificant tree cover, with grasses and flowers located between trees). Rainfall is more limited to between 500 and 1,500 millimetres (20 and 60 in) per year. The savannah zone's three categories are Guinean forest-savanna mosaic , Sudan savannah, and Sahel savannah. Guinean forest-savanna mosaic

13272-531: The Nigerian government, with Nigeria utilizing air support from Egyptian pilots provided by Gamal Abdel Nasser , while France and Israel aided the Biafrans. The Congolese government, under President Joseph-Désiré Mobutu , took an early stand on the Biafran secession, voicing strong support for the Nigerian federal government and deploying thousands of troops to fight against the secessionists . Following

13440-524: The OASIS project, a detailed study of the effects of fishing on seamount communities in the North Atlantic . Another project working towards conservation is CenSeam , a Census of Marine Life project formed in 2005. CenSeam is intended to provide the framework needed to prioritise, integrate, expand and facilitate seamount research efforts in order to significantly reduce the unknown and build towards

13608-739: The Sharie catchment area. In the Sahel region, rain is less than 500 millimetres (20 in) per year, and the Sahara Desert is encroaching. In the dry northeast corner of the country lies Lake Chad , on a shared water boundary delimitation with Niger, Chad and Cameroon. The Chad Basin is fed from the north-eastern quarter of Nigeria. The Bauchi Plateau forms the watershed between the Niger/Benue and Komadugu Yobe river systems. The flat plains of north-eastern Nigeria are geographically part of

13776-695: The average size of seamounts. Nearly 50% of guyot area and 42% of the number of guyots occur in the North Pacific Ocean, covering 342,070 km (132,070 sq mi). The largest three guyots are all in the North Pacific: the Kuko Guyot (estimated 24,600 km (9,500 sq mi)), Suiko Guyot (estimated 20,220 km (7,810 sq mi)) and the Pallada Guyot (estimated 13,680 km (5,280 sq mi)). Seamounts are often found in groupings or submerged archipelagos ,

13944-556: The bird species, 16 are endemic and six are near endemic, of which four are only shared with Príncipe. Six species are considered vulnerable , and three are critically endangered (the São Tomé ibis , São Tomé fiscal and São Tomé grosbeak ). Schistometopum thomense , a bright yellow species of caecilian , is endemic to São Tomé. As of 2010, São Tomé and Príncipe , an independent nation, had an estimated population of 167,000, most of whom lived on São Tomé island. The main language

14112-552: The border with Cameroon , where the montane land is part of the Bamenda Highlands of Cameroon. The far south is defined by its tropical rainforest climate , where annual rainfall is 1,500 to 2,000 millimetres (60 to 80 in) per year. In the southeast stands the Obudu Plateau . Coastal plains are found in both the southwest and the southeast. Mangrove swamps are found along the coast. The area near

14280-537: The border with Cameroon close to the coast is rich rainforest and part of the Cross-Sanaga-Bioko coastal forests ecoregion , an important centre for biodiversity . It is a habitat for the drill primate , which is found in the wild only in this area and across the border in Cameroon. The areas surrounding Calabar , Cross River State, also in this forest, are believed to contain the world's largest diversity of butterflies. The area of southern Nigeria between

14448-405: The caliphate and the central Sokoto administration to prevent any defence as he worked towards the capital. As the British approached the city of Sokoto , Sultan Muhammadu Attahiru I organized a quick defence of the city and fought the advancing British-led forces. The British force quickly won, sending Attahiru I and thousands of followers on a Mahdist hijra . In the northeast, the decline of

14616-477: The canals, sewerage systems that are channels for water flows, and the like. Haphazard industrial planning, increased urbanisation, poverty and lack of competence of the municipal government are seen as the major reasons for high levels of waste pollution in major cities of the country. Some of the solutions have been disastrous to the environment, resulting in untreated waste being dumped in places where it can pollute waterways and groundwater . In 2005, Nigeria had

14784-451: The chain is Annobón, also known as Pagalu, with an area of about 17.5 km (6.8 sq mi). It is an extinct volcano that rises from deep water to 598 m (1,962 ft) above sea level. The island belongs to Equatorial Guinea . The average temperature is 26.1 °C (79.0 °F), with little seasonal variation. Most rain falls from November to May, with annual precipitation averaging 1,196 mm (47.1 in) - less than on

14952-565: The civil service. Colonel Buka Suka Dimka launched a February 1976 coup attempt , during which General Murtala Muhammed was assassinated. Dimka lacked widespread support among the military, and his coup failed, forcing him to flee. After the coup attempt, General Olusegun Obasanjo was appointed military head of state. Obasanjo vowed to continue Murtala's policies. Aware of the danger of alienating northern Nigerians, Obasanjo brought General Shehu Yar'Adua as his replacement and second-in-command as Chief of Staff, Supreme Headquarters completing

15120-750: The crust to the surface. Volcanoes formed near or above subducting zones are created because the subducting tectonic plate adds volatiles to the overriding plate that lowers its melting point . Which of these two process involved in the formation of a seamount has a profound effect on its eruptive materials. Lava flows from mid-ocean ridge and plate boundary seamounts are mostly basaltic (both tholeiitic and alkalic ), whereas flows from subducting ridge volcanoes are mostly calc-alkaline lavas. Compared to mid-ocean ridge seamounts, subduction zone seamounts generally have more sodium , alkali , and volatile abundances, and less magnesium , resulting in more explosive, viscous eruptions. All volcanic seamounts follow

15288-490: The cultural and political differences were sharp among Nigeria's dominant ethnic groups: the Hausa in the north, Igbo in the east and Yoruba in the west. The Westminster system of government was retained, and thus the President 's powers were generally ceremonial. The parliamentary system of government had Abubakar Tafawa Balewa as Prime Minister and Nnamdi Azikiwe as the ceremonial president. The founding government

15456-570: The dictator died in the villa. He looted money to offshore accounts in Western European banks and defeated coup plots by arresting and bribing generals and politicians. His successor, General Abdulsalami Abubakar , adopted a new constitution on 5 May 1999, which provided for multiparty elections. On 29 May 1999, Abubakar handed over power to the winner of the 1999 presidential election, former military ruler General Olusegun Obasanjo , as President of Nigeria. Obasanjo had been in prison under

15624-516: The dictatorship of Abacha. Obasanjo's inauguration heralded the beginning of the Fourth Nigerian Republic, ending a 39-year period of short-lived democracies, civil war and military dictatorship. Although the elections that brought Obasanjo to power and allowed him to run for a second term in the 2003 presidential elections were condemned as unfree and unfair, Nigeria made significant progress in democratization under Obasanjo. In

15792-622: The direct control of the British government and established the Southern Nigeria Protectorate as a British protectorate and part of the British Empire . By 1902, the British had begun plans to move north into the Sokoto Caliphate. British General Lord Frederick Lugard was tasked by the Colonial Office to implement the agenda. Lugard used rivalries between many of the emirs in the southern reach of

15960-561: The duo of Moshood Abiola and Baba Gana Kingibe of the Social Democratic Party defeated Bashir Tofa and Sylvester Ugoh of the National Republican Convention by over 2.3 million votes. However, Babangida annulled the elections, leading to massive civilian protests that effectively shut down the country for weeks. In August 1993, Babangida finally kept his promise to relinquish power to

16128-723: The earliest known sculptures in sub-Saharan Africa and smelted iron by about 550 BC and possibly a few centuries earlier. Evidence of iron smelting has also been excavated at sites in the Nsukka region of southeast Nigeria: dating to 2000 BC at the site of Lejja and to 750 BC and at the site of Opi . The Kano Chronicle highlights an ancient history dating to around 999 AD of the Hausa Sahelian city-state of Kano , with other major Hausa cities (or Hausa Bakwai ) of Daura , Hadeija , Kano , Katsina , Zazzau , Rano , and Gobir all having recorded histories dating back to

16296-425: The effect of seamounts on endemicity. They have , however, been confidently shown to provide a habitat to species that have difficulty surviving elsewhere. The volcanic rocks on the slopes of seamounts are heavily populated by suspension feeders , particularly corals , which capitalize on the strong currents around the seamount to supply them with food. These coral are therefore host to numerous other organisms in

16464-792: The emergence of a wave of terror by the Boko Haram insurgency , such as the Gwoza massacre and Chibok schoolgirls kidnapping in 2014. Ahead of the general election of 2015 , a merger of the biggest opposition parties in Nigeria – the Action Congress of Nigeria , the Congress for Progressive Change , the All Nigeria Peoples Party , a faction of the All Progressives Grand Alliance and

16632-522: The first time since the return of democracy, no former military ruler ran for president, marking a strengthening of democracy and faith in the multiparty constitution . The election also saw the rise of metonymic supporters of the new candidates, the Obidient movement of Peter Obi , previously governor of Anambra State, widely appealed to young, urban voters and has his core base in the Southeast; and

16800-465: The first two have any potential of being targeted by mining in the next few decades. Some seamounts have not been mapped and thus pose a navigational danger. For instance, Muirfield Seamount is named after the ship that hit it in 1973. More recently, the submarine USS San Francisco ran into an uncharted seamount in 2005 at a speed of 35 knots (40.3 mph; 64.8 km/h), sustaining serious damage and killing one seaman. One major seamount risk

16968-417: The fish that feed on them aggregate, in turn falling prey to further predation, making seamounts important biological hotspots. Seamounts provide habitats and spawning grounds for these larger animals, including numerous fish. Some species, including black oreo (Allocyttus niger) and blackstripe cardinalfish (Apogon nigrofasciatus) , have been shown to occur more often on seamounts than anywhere else on

17136-416: The forest zone's most southerly portion, especially around the Niger River and Cross River deltas, is mangrove swamp . North of this is a freshwater swamp, containing different vegetation from the saltwater mangrove swamps, and north of that is a rainforest. The savannah zone's three categories are divided into Guinean forest-savanna mosaic , made up of plains of tall grass which are interrupted by trees,

17304-528: The highest rate of deforestation in the world, according to the Food and Agriculture Organization of the United Nations . That year, 12.2%, the equivalent of 11,089,000 hectares, had been forested in the country. Between 1990 and 2000, Nigeria lost an average of 409,700 hectares of forest every year equal to an average annual deforestation rate of 2.4%. Between 1990 and 2005, in total Nigeria lost 35.7% of its forest cover or around 6,145,000 hectares. Nigeria had

17472-407: The inlets to irrigate agricultural land. Nigeria is covered by three types of vegetation: forests (where there is significant tree cover), savannahs (insignificant tree cover, with grasses and flowers located between trees), and montane land (least common and mainly found in the mountains near the Cameroon border). Both the forest zone and the savannah zone are divided into three parts. Some of

17640-544: The island and exported via tanker. The Western High Plateau, also called the Western Highlands or the Bamenda Grassfields, continues the Cameroon line into the mainland of Cameroon. The plateau rises in steps from the west. To the east, it terminates in mountains that range in height from 1,000 m (3,300 ft) to 2,500 metres (8,200 ft). The plateau gives way to the Adamawa Plateau to

17808-436: The largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface, such flat-top seamounts are called " guyots " or "tablemounts". Earth's oceans contain more than 14,500 identified seamounts, of which 9,951 seamounts and 283 guyots, covering a total area of 8,796,150 km (3,396,210 sq mi), have been mapped but only

17976-497: The last few decades. Before consistent conservation efforts can begin, the seamounts of the world must first be mapped , a task that is still in progress. Overfishing is a serious threat to seamount ecological welfare. There are several well-documented cases of fishery exploitation, for example the orange roughy ( Hoplostethus atlanticus ) off the coasts of Australia and New Zealand and the pelagic armorhead ( Pseudopentaceros richardsoni ) near Japan and Russia. The reason for this

18144-516: The late-19th and early-20th centuries. San Joaquin , also known as Pico Biao or Pico do Moka, is 2,009 m (6,591 ft) high, on the southeast of the island. The summit is cut by a small lake-filled caldera , and there is a crater lake on the NE flank. San Joaquin has been active during the last 2,000 years. The southwestern side of Bioko is rainy for most of the year, with annual rainfall in some locations of 10,000 mm (394 in). The climate

18312-477: The leadership of Sir George Taubman Goldie . By the late 19th and early 20th centuries, the company had vastly succeeded in subjugating the independent southern kingdoms along the Niger River , the British conquered Benin in 1897, and, in the Anglo-Aro War (1901–1902), defeated other opponents. The defeat of these states opened up the Niger area to British rule. In 1900, the company's territory came under

18480-476: The location of a large area of Central African mangroves . Nigeria's most expansive topographical region is that of the valleys of the Niger and Benue river valleys (which merge and form a Y-shape). To the southwest of the Niger is a "rugged" highland . To the southeast of the Benue are hills and mountains, which form the Mambilla Plateau , the highest plateau in Nigeria. This plateau extends through

18648-479: The lower levels. San Carlos is 2,260 m (7,410 ft) high with a broad summit caldera, lying at the extreme SW of the island. The volcano dates from the Holocene age and has been active within the last 2000 years. Santa Isabel is the largest volcano at 3,007 m (9,865 ft) in height, and contains many satellite cinder cones. Three eruptions have been reported from vents on the southeast flank during

18816-602: The mainland, the line starts with Mount Cameroon and extends northeast in a range known as the Western High Plateau , home to the Cameroonian Highlands forests . Volcanic swells further inland are Manengouba , Bamboutu and the Oku Massif . East of Oku there are further volcanic mountains in the Ngaoundere Plateau , some of which appear to have similar origins. The southernmost island in

18984-519: The mainland. Annobón has lush valleys and steep mountains, covered with rich woods and luxuriant vegetation. The small population lives in one community, practicing some agriculture but mainly living by fishing. São Tomé island is 854 km (330 sq mi) in area, lying almost on the equator. The entire island is a massive shield volcano which rises from the floor of the Atlantic Ocean , over 3,000 m (10,000 ft) below sea level, and reaches 2,024 m (6,640 ft) above sea level in

19152-620: The major coastal ports. Some of the more prolific slave-trading kingdoms who participated in the Atlantic slave trade were linked with the Edo's Benin Empire in the south, Oyo Empire in the southwest, and the Aro Confederacy in the southeast. Benin's power lasted between the 15th and 19th centuries. Oyo, at its territorial zenith in the late 17th to early 18th centuries, extended its influence from western Nigeria to modern-day Togo . In

19320-461: The middle reaches of the river around Timbuktu before 19th-century European colonialism . Before Flora Shaw suggested the name Nigeria , other proposed names included Royal Niger Company Territories , Central Sudan , Niger Empire , Niger Sudan , and Hausa Territories . Kainji Dam excavations showed ironworking by the 2nd century BC. The transition from Neolithic times to the Iron Age

19488-418: The military triumvirate, with Obasanjo as head of state and General Theophilus Danjuma as Chief of Army Staff , the three went on to re-establish control over the military regime and organized the military's transfer of power programme: states creation and national delimitation , local government reforms and the constitutional drafting committee for a new republic. The military carefully planned

19656-403: The most common across the country; Sudan savannah, with short grasses and short trees; and Sahel savannah patches of grass and sand, found in the northeast. Waste management including sewage treatment , the linked processes of deforestation and soil degradation , and climate change or global warming are the major environmental problems in Nigeria. Waste management presents problems in

19824-530: The most common, and least understood, marine structures and biomes on Earth, a sort of exploratory frontier. Most seamounts are built by one of two volcanic processes, although some, such as the Christmas Island Seamount Province near Australia, are more enigmatic. Volcanoes near plate boundaries and mid-ocean ridges are built by decompression melting of rock in the upper mantle . The lower density magma rises through

19992-539: The new PDP (a faction of serving governors of the ruling People's Democratic Party) – formed the All Progressives Congress led by current president Bola Ahmed Tinubu. At the time, it was the most expensive election ever to be held on the African continent (being surpassed only by the elections of 2019 and 2023 ). The new mega-opposition party chose as their candidate for the election former military dictator Muhammadu Buhari. Buhari's campaign in 2015

20160-434: The new caliph. Lugard abolished the caliphate but retained the title sultan as a symbolic position in the newly organized Northern Nigeria Protectorate . This remnant became known as " Sokoto Sultanate Council ". In June 1903, the British defeated the remaining northern forces of Attahiru. By 1906, all resistance to British rule had ended. On 1 January 1914, the British formally united the Southern Nigeria Protectorate and

20328-514: The north , Chad in the northeast , Cameroon in the east , and Benin in the west . Nigeria is a federal republic comprising 36 states and the Federal Capital Territory , where its capital, Abuja , is located. The largest city in Nigeria is Lagos , one of the largest metropolitan areas in the world and the largest in Africa . Nigeria has been home to several indigenous pre-colonial states and kingdoms since

20496-579: The north, the incessant fighting amongst the Hausa city-states and the decline of the Bornu Empire allowed the Fulani people to gain headway into the region. Until this point, the Fulani, a nomadic ethnic group, primarily traversed the semi-desert Sahelian region north of Sudan with cattle and avoided trade and intermingling with the Sudanic peoples. At the beginning of the 19th century, Usman dan Fodio led

20664-469: The northeast, a larger but less rugged region. The Western High Plateau features several dormant volcanoes , including the Bamboutos Mountains , Mount Oku , and Mount Kupe . Crater lakes dot the plateau, the result of dead volcanoes filling with water. This includes Lake Barombi Mbo and Lake Bermin , which have the highest number of endemic fish species per area recorded anywhere in

20832-470: The ocean floor. Marine mammals , sharks , tuna , and cephalopods all congregate over seamounts to feed, as well as some species of seabirds when the features are particularly shallow. Seamounts often project upwards into shallower zones more hospitable to sea life, providing habitats for marine species that are not found on or around the surrounding deeper ocean bottom. Because seamounts are isolated from each other they form "undersea islands" creating

21000-470: The ocean makes up 70% of Earth's surface area, technological challenges have severely limited the extent of deep sea mining . But with the constantly decreasing supply on land, some mining specialists see oceanic mining as the destined future, and seamounts stand out as candidates. Seamounts are abundant, and all have metal resource potential because of various enrichment processes during the seamount's life. An example for epithermal gold mineralization on

21168-516: The official Nigerian government side attacked Biafra on 6 July 1967, at Garkem. The 30-month war, with a long blockade of Biafra and its isolation from trade and international relief, ended in January 1970. Estimates of the number of dead in the former Eastern Region during the 30-month civil war range from one to three million. Britain and the Soviet Union were the main military backers of

21336-516: The plotters struggled to form a central government. Senate President Nwafor Orizu handed over government control to the Army , under the command of another Igbo officer, Major General Johnson Aguiyi-Ironsi . Later, the counter-coup of 1966, supported primarily by Northern military officers, facilitated the rise of Yakubu Gowon as military head of state. Tension rose between north and south; Igbos in northern cities suffered persecution and many fled to

21504-551: The primary ecological havens on the seamount is its deep sea coral garden, and many of the specimens noted were over a century old. Following the expansion of knowledge on the seamount there was extensive support to make it a marine sanctuary , a motion that was granted in 2008 as part of the Monterey Bay National Marine Sanctuary . Much of what is known about seamounts ecologically is based on observations from Davidson. Another such seamount

21672-495: The protectorates. Under Britain's policy of indirect rule and validation of Islamic legitimist tradition, the Crown did not encourage the operation of Christian missions in the northern, Islamic part of the country. By the mid-20th century following World War II , a wave for independence was sweeping across Africa, in response to the growth of Nigerian nationalism and demands for independence, successive constitutions legislated by

21840-633: The rain shadow to the northeast of São Tomé the vegetation is dry savannah, with only 60 cm (24 in) of rain each year. By contrast, the lush south and west of the island receive about 6 m (20 ft) of rain, mostly falling in March and April. The climate is hot and humid with the rainy season from October to May. The higher slopes of the island are forested and form part of the Obo National Park. São Tomé has never been connected to Africa, and therefore has many unique plants and birds. Of

22008-573: The region Slave Coast . Europeans traded goods with peoples at the coast; coastal trade with Europeans also marked the beginnings of the Atlantic slave trade . The port of Calabar on the historical Bight of Biafra (now commonly referred to as the Bight of Bonny) became one of the largest slave-trading posts in West Africa in this era. Other major slaving ports were located in Badagry , Lagos on

22176-570: The region a cooler climate than the rest of Cameroon. For example, the average temperature at Dschang in the West Province is 20 °C (68 °F). Toward the north, rainfall levels are reduced as the Sudan climate becomes predominant. The Western High Plateau's relief and high rainfall make it a major watershed for Cameroon. Important rivers in the region include the Manyu , which rises in

22344-727: The resettlement of slaves freed by Britain in North America after the American Revolutionary War . Britain intervened in the Lagos kingship power struggle by bombarding Lagos in 1851, deposing the slave-trade-friendly Oba Kosoko , helping to install the amenable Oba Akitoye and signing the Treaty between Great Britain and Lagos on 1   January 1852. Britain annexed Lagos as a crown colony in August 1861 with

22512-536: The return to civilian rule putting in place measures to ensure that political parties had broader support than witnessed during the first republic. In 1979, five political parties competed in a series of elections in which Alhaji Shehu Shagari of the National Party of Nigeria (NPN) was elected president. All five parties won representation in the National Assembly. On 1 October 1979, Shehu Shagari

22680-399: The right technology available, only a scant 1% of the total number have been explored, and sampling and information remains biased towards the top 500 m (1,640 ft). New species are observed or collected and valuable information is obtained on almost every submersible dive at seamounts. Before seamounts and their oceanographic impact can be fully understood, they must be mapped,

22848-439: The same biogeographical interest. As they are formed from volcanic rock , the substrate is much harder than the surrounding sedimentary deep sea floor. This causes a different type of fauna to exist than on the seafloor, and leads to a theoretically higher degree of endemism . However, recent research especially centered at Davidson Seamount suggests that seamounts may not be especially endemic, and discussions are ongoing on

23016-728: The seafloor is Conical Seamount, located about 8 km south of Lihir Island in Papua New Guinea. Conical Seamount has a basal diameter of about 2.8 km and rises about 600 m above the seafloor to a water depth of 1050 m. Grab samples from its summit contain the highest gold concentrations yet reported from the modern seafloor (max. 230 g/t Au, avg. 26 g/t, n=40). Iron - manganese , hydrothermal iron oxide , sulfide , sulfate , sulfur , hydrothermal manganese oxide , and phosphorite (the latter especially in parts of Micronesia) are all mineral resources that are deposited upon or within seamounts. However, only

23184-416: The seafloor to 1,000–4,000 m (3,300–13,100 ft) in height. They are defined by oceanographers as independent features that rise to at least 1,000 m (3,281 ft) above the seafloor, characteristically of conical form. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea . During their evolution over geologic time,

23352-475: The seamount moves with the tectonic plate towards a subduction zone . Here it is subducted under the plate margin and ultimately destroyed, but it may leave evidence of its passage by carving an indentation into the opposing wall of the subduction trench. The majority of seamounts have already completed their eruptive cycle, so access to early flows by researchers is limited by late volcanic activity. Ocean-ridge volcanoes in particular have been observed to follow

23520-529: The seamount's life. In addition soft sediments tend to accumulate on seamounts, which are typically populated by polychaetes ( annelid marine worms ) oligochaetes ( microdrile worms), and gastropod mollusks ( sea slugs ). Xenophyophores have also been found. They tend to gather small particulates and thus form beds, which alters sediment deposition and creates a habitat for smaller animals. Many seamounts also have hydrothermal vent communities, for example Suiyo and Kamaʻehuakanaloa seamounts. This

23688-528: The second millennium BC, with the Nok civilization in the 15th century BC marking the first internal unification. The modern state originated with British colonialization in the 19th century, taking its present territorial shape with the merging of the Southern Nigeria Protectorate and the Northern Nigeria Protectorate in 1914. The British set up administrative and legal structures while practicing indirect rule through traditional chiefdoms . Nigeria became

23856-587: The separatist Ambazonia ) 1,690 km or 1,050 mi. Its coastline is at least 853 km (530 mi). Nigeria lies between latitudes 4° and 14°N , and longitudes 2° and 15°E . The highest point in Nigeria is Chappal Waddi at 2,419 m (7,936 ft). The main rivers are the Niger and the Benue , which converge and empty into the Niger Delta . This is one of the world's largest river deltas and

24024-468: The shear zone is reactivating. The Benue Trough lies to the west of the Cameroon line. The Benue Trough was formed by rifting of the central West African basement, beginning at the start of the Cretaceous era. A common explanation of the trough's formation is that it is an aulacogen , an abandoned arm of a three-armed radial rift system. The other two arms continued to spread during the break-up of Gondwana , as South America separated from Africa. During

24192-480: The shear zone, and may be associated with the Cameroon line. 3°30′0″N 8°42′0″E  /  3.50000°N 8.70000°E  / 3.50000; 8.70000 Seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface ( sea level ), and thus is not an island , islet , or cliff -rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from

24360-704: The smallest seamounts found in the Arctic Ocean and the Mediterranean and Black Seas; whilst the largest mean seamount size, 890 km (340 sq mi), occurs in the Indian Ocean . The largest seamount has an area of 15,500 km (6,000 sq mi) and it occurs in the North Pacific. Guyots cover a total area of 707,600 km (273,200 sq mi) and have an average area of 2,500 km (970 sq mi), more than twice

24528-501: The south to 946 m (3,104 ft) at Pico de Príncipe , in a thickly forested area within the Obo National Park. The north and centre of the island were formerly plantations but have largely reverted to forest. As with São Tomé, the island has always been isolated from the mainland and therefore has many unique species of plants and animals, including six endemic birds. Príncipe has a population of around 5,000 people. Other than Portuguese , some speak Principense or Lunguyê with

24696-454: The threshold of power in the country. As oil production and revenue rose, the Nigerian government became increasingly dependent on oil revenues and international commodity markets for budgetary and economic concerns. The coup in July 1975 , led by Generals Shehu Musa Yar'Adua and Joseph Garba , ousted Gowon, who fled to Britain. The coup plotters wanted to replace Gowon's autocratic rule with

24864-452: The time of their deposition, this would have been 500 m (1,640 ft) up the flank of the volcano, far too high for a normal wave to reach. The date corresponded with a massive flank collapse at the nearby Mauna Loa , and it was theorized that it was a massive tsunami, generated by the landslide, that deposited the fossils. Geology Ecology Geography and geology Ecology Nigeria Nigeria , officially

25032-490: The volcanic activities. The puzzling feature, that the composition of the magmas is the same both in the land volcanoes and the oceanic ones is likely explained by recent studies that show the underlying lithosphere is the same. A gravity study of the southern part of the Adamawa plateau has shown a belt of dense rocks at an average depth of 8 km running parallel to the Foumban shear zone. The material appears to be an igneous intrusion that may have accompanied reactivation of

25200-413: The war, Nigeria enjoyed an oil boom in the 1970s, during which the country joined OPEC and received huge oil revenues. Despite these revenues, the military government did little to improve the standard of living , help small and medium businesses, or invest in infrastructure. As oil revenues fueled the rise of federal subsidies to states, the federal government became the centre of political struggle and

25368-502: The waters of this country". In August 1983, Shagari and the NPN were returned to power in a landslide victory, with a majority of seats in the National Assembly and control of 12 state governments. But the elections were marred by violence, and allegations of widespread vote-rigging and electoral malfeasance led to legal battles over the results. There were also uncertainties, such as in the first republic, that political leaders may be unable to govern properly. The 1983 military coup d'état

25536-415: The western coast along the south of the West African craton . The coastline roughly corresponds to the coast of the Borborema geological province of northeastern Brazil, which began to separate from this part Africa around 115 million years ago. The Central African Shear Zone (CASZ), a lineament that extends from the Sudan to coastal Cameroon, runs under the continental section of the Cameroon line. It

25704-419: The widespread cultivation of agricultural products, such as the palm, for use in European industry. The slave trade continued after the ban, as illegal smugglers purchased slaves along the coast from native slavers. Britain's West Africa Squadron sought to intercept the smugglers at sea. The rescued slaves were taken to Freetown , a colony in West Africa originally established by Lieutenant John Clarkson for

25872-491: The world, about two million, was concentrated in the territories of the Sokoto Caliphate . The use of slave labour was extensive, especially in agriculture. By the time of its break-up in 1903 into various European colonies, the Sokoto Caliphate was one of the largest pre-colonial African states. A changing legal imperative (the outlawing of the Atlantic slave trade in 1807) and economic imperative (a desire for political and social stability) led most European powers to support

26040-418: The world. The 4,095 m (13,435 ft) Mount Cameroon on the coastline, which may have been observed by the Carthaginian Hanno the Navigator in the 5th century BC, erupted in 2000. Further inland, the stratovolcano Mount Oku at 3,011 metres (9,879 ft) is the second highest mountain in sub-Saharan mainland West Africa . In 1986, Lake Nyos , a crater lake in the Oku volcanic plain , released

26208-453: The world. Interactions between seamounts and underwater currents, as well as their elevated position in the water, attract plankton , corals , fish, and marine mammals alike. Their aggregational effect has been noted by the commercial fishing industry , and many seamounts support extensive fisheries. There are ongoing concerns on the negative impact of fishing on seamount ecosystems, and well-documented cases of stock decline, for example with

26376-471: The younger lithosphere below the Atlantic, one explanation is that the source is in the asthenosphere rather than in metasomatized lithosphere. A different view is that the similarities are caused by shallow contamination of the oceanic section, which could be caused by sediments from the continent or by rafted crustal blocks that were trapped in the oceanic lithosphere during the separation between South America and Africa. According to some geologists, there

26544-408: Was a coalition of conservative parties: the Northern People's Congress led by Sir Ahmadu Bello , a party dominated by Muslim northerners, and the Igbo and Christian-dominated National Council of Nigeria and the Cameroons led by Nnamdi Azikiwe . The opposition consisted of the comparatively liberal Action Group , which was largely dominated by the Yoruba and led by Obafemi Awolowo . An imbalance

26712-425: Was abolished soon after colonialism. Nigeria gained a degree of self-rule in 1954, and full independence from the United Kingdom on 1 October 1960, as the Federation of Nigeria with Abubakar Tafawa Balewa as its Prime Minister , while retaining the British monarch , Elizabeth II , as nominal head of state and Queen of Nigeria . Azikiwe replaced the colonial governor-general in November 1960. At independence,

26880-567: Was accomplished without intermediate bronze production. Some have suggested the technology moved west from the Nile Valley . But the Iron Age in the Niger River valley and the forest region appears to predate the introduction of metallurgy in the upper savanna by more than 800 years, as well as predating it in the Nile Valley. More recent research suggests that iron metallurgy was developed independently in sub-Saharan Africa . The Nok civilization thrived between 1,500 BC and AD 200. It produced life-sized terracotta figures that are some of

27048-403: Was coordinated by key officers of the Nigerian military and led to the overthrow of the government and the installation of Major General Muhammadu Buhari as head of state. The military coup of Muhammadu Buhari shortly after the regime's re-election in 1984 was generally viewed as a positive development. In 1985, Ibrahim Babangida overthrew Buhari in a coup d'état. In 1986, Babangida established

27216-412: Was created in the polity as the result of the 1961 plebiscite . Southern Cameroons opted to join the Republic of Cameroon while Northern Cameroons chose to join Nigeria. The northern part of the country became larger than the southern part. The disequilibrium and perceived corruption of the electoral and political process led to two military coups in 1966. The first coup was in January 1966 and

27384-404: Was led mostly by soldiers under Majors Emmanuel Ifeajuna (of the Igbo tribe), Chukwuma Kaduna Nzeogwu ( Northerner of Eastern extraction) and Adewale Ademoyega (a Yoruba from the West). The coup plotters succeeded in assassinating Sir Ahmadu Bello and Sir Abubakar Tafawa Balewa alongside prominent leaders of the Northern Region and Premier Samuel Akintola of the Western Region , but

27552-405: Was once heavily forested. However, repeated cutting and burning by humans has forced the forest back to areas along the waterways and has allowed grasslands to expand into the area. Sudan savanna forms the dominant vegetation. This consists of grassfields—leading to the name Bamenda grassfields around the city of Bamenda —and short shrubs and trees that shed their foliage during the dry season as

27720-418: Was popular and built around his image as a staunch anti-corruption fighter—he won the election by over two million votes. Observers generally praised the election as being fair. The election marked the first time an incumbent president had lost re-election in Nigeria. In the 2019 presidential election , Buhari was re-elected. Four candidates vied for the presidency in the 2023 presidential election . For

27888-822: Was published in 2008. The effect that seamounts have on fish populations has not gone unnoticed by the commercial fishing industry . Seamounts were first extensively fished in the second half of the 20th century, due to poor management practices and increased fishing pressure seriously depleting stock numbers on the typical fishing ground, the continental shelf . Seamounts have been the site of targeted fishing since that time. Nearly 80 species of fish and shellfish are commercially harvested from seamounts, including spiny lobster (Palinuridae), mackerel (Scombridae and others), red king crab ( Paralithodes camtschaticus ), red snapper ( Lutjanus campechanus ), tuna (Scombridae), Orange roughy ( Hoplostethus atlanticus ), and perch (Percidae). The ecological conservation of seamounts

28056-440: Was sworn in as the first President and Commander-in-Chief of the Federal Republic of Nigeria. Obasanjo peacefully transferred power to Shagari, becoming the first head of state in Nigerian history to willingly step down. The Shagari government became viewed as corrupt by virtually all sectors of Nigerian society. In 1983, the inspectors of the state-owned Nigerian National Petroleum Corporation began to notice "the slow poisoning of

28224-501: Was the country's national anthem from 1960 to 1978, as its national anthem, replacing Arise, O Compatriots . Nigeria is located in western Africa on the Gulf of Guinea and has a total area of 923,768 km (356,669 sq mi), making it the world's 32nd-largest country . Its borders span 4,047 kilometres (2,515 mi), and it shares borders with Benin (773 km or 480 mi), Niger (1,497 km or 930 mi), Chad (87 km or 54 mi), and Cameroon (including

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