1.
Americas
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The Americas, also collectively called America, encompass the totality of the continents of North America and South America. Together they make up most of the land in Earths western hemisphere, along with their associated islands, they cover 8% of Earths total surface area and 28. 4% of its land area. The topography is dominated by the American Cordillera, a chain of mountains that runs the length of the west coast. The flatter eastern side of the Americas is dominated by river basins, such as the Amazon, St. Lawrence River / Great Lakes basin, Mississippi. Humans first settled the Americas from Asia between 42,000 and 17,000 years ago, a second migration of Na-Dene speakers followed later from Asia. The subsequent migration of the Inuit into the neoarctic around 3500 BCE completed what is regarded as the settlement by the indigenous peoples of the Americas. The first known European settlement in the Americas was by the Norse explorer Leif Ericson, however, the colonization never became permanent and was later abandoned. The voyages of Christopher Columbus from 1492 to 1502 resulted in permanent contact with European powers, diseases introduced from Europe and Africa devastated the indigenous peoples, and the European powers colonized the Americas. Mass emigration from Europe, including numbers of indentured servants. Decolonization of the Americas began with the American Revolution in 1776, the population is over 1 billion, with over 65% of them living in one of the three most populous countries. As of the beginning of the 2010s, the most populous urban agglomerations are Mexico City, New York, Sao Paulo, Los Angeles, Buenos Aires and Rio de Janeiro, all of them megacities. The name America was first recorded in 1507 in the Cosmographiae Introductio, apparently written by Matthias Ringmann and it first applied to both North and South America by Gerardus Mercator in 1538. Amerigen means land of Amerigo and derives from Amerigo and gen, America accorded with the feminine names of Asia, Africa, and Europa. When conceived as a continent, the form is generally the continent of America in the singular. However, without a context, singular America in English commonly refers to the United States of America. In some countries of the world, America is considered a continent encompassing the North America and South America subcontinents, the first inhabitants migrated into the Americas from Asia. Habitation sites are known in Alaska and the Yukon from at least 20,000 years ago, beyond that, the specifics of the Paleo-Indian migration to and throughout the Americas, including the dates and routes traveled, are subject to ongoing research and discussion. Widespread habitation of the Americas occurred during the glacial maximum
2.
Central America
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Central America is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. Central America is bordered by Mexico to the north, Colombia to the southeast, the Caribbean Sea to the east, Central America consists of seven countries, Belize, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica and Panama. The combined population of Central America is between 41,739,000 and 42,688,190, Central America is a part of the Mesoamerican biodiversity hotspot, which extends from northern Guatemala through to central Panama. Due to the presence of several active faults and the Central America Volcanic Arc. Volcanic eruptions and earthquakes occur frequently, these disasters have resulted in the loss of many lives. In the Pre-Columbian era, Central America was inhabited by the peoples of Mesoamerica to the north and west. Soon after Christopher Columbuss voyages to the Americas, the Spanish began to colonize the Americas, the seven states finally became independent autonomous states, beginning with Nicaragua, Honduras, Costa Rica, and Guatemala, followed by El Salvador, then Panama, and finally Belize. Middle America is usually thought to comprise Mexico to the north of the 7 states of Central America as well as Colombia, usually the whole of the Caribbean to the north-east and sometimes the Guyanas are also included. According to one source, the term Central America was used as a synonym for Middle America as recently as 1962, in Brazil, Central America comprises all countries between Mexico and Colombia, including those in the Caribbean. Mexico, in whole or in part, is included by British people. For the people living in the 5 countries formerly part of the Federal Republic of Central America there is a distinction between the Spanish language terms América Central and Centroamérica, in the Pre-Columbian era, the northern areas of Central America were inhabited by the indigenous peoples of Mesoamerica. Most notable among these were the Mayans, who had built numerous cities throughout the region, and the Aztecs, following Christopher Columbuss voyages to the Americas, the Spanish sent many expeditions to the region, and they began their conquest of Maya territory in 1523. Soon after the conquest of the Aztec Empire, Spanish conquistador Pedro de Alvarado commenced the conquest of northern Central America for the Spanish Empire. Beginning with his arrival in Soconusco in 1523, Alvarados forces systematically conquered and subjugated most of the major Maya kingdoms, including the Kiche, Tzutujil, Pipil, and the Kaqchikel. By 1528, the conquest of Guatemala was nearly complete, with only the Petén Basin remaining outside the Spanish sphere of influence, the last independent Maya kingdoms – the Kowoj and the Itza people – were finally defeated in 1697, as part of the Spanish conquest of Petén. In 1538, Spain established the Real Audiencia of Panama, which had jurisdiction over all land from the Strait of Magellan to the Gulf of Fonseca. This entity was dissolved in 1543, and most of the territory within Central America then fell under the jurisdiction of the Audiencia Real de Guatemala. This area included the current territories of Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and the Mexican state of Chiapas, the president of the Audiencia, which had its seat in Antigua Guatemala, was the governor of the entire area
3.
Guatemala
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With an estimated population of around 15.8 million, it is the most populated state in Central America. Guatemala is a democracy, its capital and largest city is Nueva Guatemala de la Asunción. The territory of modern Guatemala once formed the core of the Maya civilization, most of the country was conquered by the Spanish in the 16th century, becoming part of the viceroyalty of New Spain. Guatemala attained independence in 1821 as part of the Federal Republic of Central America, from the mid to late 19th century, Guatemala experienced chronic instability and civil strife. Beginning in the early 20th century, it was ruled by a series of dictators backed by the United Fruit Company, in 1944, authoritarian leader Jorge Ubico was overthrown by a pro-democratic military coup, initiating a decade-long revolution that led to sweeping social and economic reforms. A U. S. -backed military coup in 1954 ended the revolution, from 1960 to 1996, Guatemala endured a bloody civil war fought between the US-backed government and leftist rebels, including genocidal massacres of the Maya population perpetrated by the military. As of 2014, Guatemala ranks 31st of 33 Latin American and Caribbean countries in terms of the Human Development Index, Guatemalas abundance of biologically significant and unique ecosystems includes a large number of endemic species and contributes to Mesoamericas designation as a biodiversity hotspot. The country is known for its rich and distinct culture. The name Guatemala comes from the Nahuatl word Cuauhtēmallān, or place of many trees and this was the name the Tlaxcaltecan soldiers who accompanied Pedro de Alvarado during the Spanish Conquest gave to this territory. The first evidence of habitation in Guatemala dates back to 12,000 BC. Evidence, such as obsidian arrowheads found in parts of the country. There is archaeological proof that early Guatemalan settlers were hunters and gatherers, pollen samples from Petén and the Pacific coast indicate that maize cultivation had been developed by 3500 BC. Sites dating back to 6500 BC have been found in the Quiché region in the Highlands, archaeologists divide the pre-Columbian history of Mesoamerica into the Preclassic period, the Classic period, and the Postclassic period. Until recently, the Preclassic was regarded as a period, with small villages of farmers who lived in huts. This period is characterized by urbanisation, the emergence of independent city-states and this lasted until approximately 900 AD, when the Classic Maya civilization collapsed. The Maya abandoned many of the cities of the lowlands or were killed off by a drought-induced famine. The cause of the collapse is debated, but the Drought Theory is gaining currency, supported by such as lakebeds, ancient pollen. A series of prolonged droughts, among other such as overpopulation, in what is otherwise a seasonal desert is thought to have decimated the Maya
4.
Mexico
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Mexico, officially the United Mexican States, is a federal republic in the southern half of North America. It is bordered to the north by the United States, to the south and west by the Pacific Ocean, to the southeast by Guatemala, Belize, and the Caribbean Sea, and to the east by the Gulf of Mexico. Covering almost two million square kilometers, Mexico is the sixth largest country in the Americas by total area, Mexico is a federation comprising 31 states and a federal district that is also its capital and most populous city. Other metropolises include Guadalajara, Monterrey, Puebla, Toluca, Tijuana, pre-Columbian Mexico was home to many advanced Mesoamerican civilizations, such as the Olmec, Toltec, Teotihuacan, Zapotec, Maya and Aztec before first contact with Europeans. In 1521, the Spanish Empire conquered and colonized the territory from its base in Mexico-Tenochtitlan, Three centuries later, this territory became Mexico following recognition in 1821 after the colonys Mexican War of Independence. The tumultuous post-independence period was characterized by instability and many political changes. The Mexican–American War led to the cession of the extensive northern borderlands, one-third of its territory. The Pastry War, the Franco-Mexican War, a civil war, the dictatorship was overthrown in the Mexican Revolution of 1910, which culminated with the promulgation of the 1917 Constitution and the emergence of the countrys current political system. Mexico has the fifteenth largest nominal GDP and the eleventh largest by purchasing power parity, the Mexican economy is strongly linked to those of its North American Free Trade Agreement partners, especially the United States. Mexico was the first Latin American member of the Organisation for Economic Co-operation and Development and it is classified as an upper-middle income country by the World Bank and a newly industrialized country by several analysts. By 2050, Mexico could become the fifth or seventh largest economy. The country is considered both a power and middle power, and is often identified as an emerging global power. Due to its culture and history, Mexico ranks first in the Americas. Mexico is a country, ranking fourth in the world by biodiversity. In 2015 it was the 9th most visited country in the world, Mexico is a member of the United Nations, the World Trade Organization, the G8+5, the G20, the Uniting for Consensus and the Pacific Alliance. Mēxihco is the Nahuatl term for the heartland of the Aztec Empire, namely, the Valley of Mexico, and its people, the Mexica and this became the future State of Mexico as a division of New Spain prior to independence. It is generally considered to be a toponym for the valley became the primary ethnonym for the Aztec Triple Alliance as a result. After New Spain won independence from Spain, representatives decided to name the new country after its capital and this was founded in 1524 on top of the ancient Mexica capital of Mexico-Tenochtitlan
5.
Caribbean Sea
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The Caribbean Sea is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. The entire area of the Caribbean Sea, the islands of the West Indies. The Caribbean Sea is one of the largest seas and has an area of about 2,754,000 km2, the seas deepest point is the Cayman Trough, between the Cayman Islands and Jamaica, at 7,686 m below sea level. The Caribbean coastline has many gulfs and bays, the Gulf of Gonâve, Gulf of Venezuela, Gulf of Darién, Golfo de los Mosquitos, Gulf of Paria, the Caribbean Sea has the worlds second biggest barrier reef, the Mesoamerican Barrier Reef. It runs 1,000 km along the coasts of Mexico, Belize, Guatemala, the name Caribbean derives from the Caribs, one of the regions dominant Native American groups at the time of European contact during the late 15th century. During the first century of development, Spanish dominance in the region remained undisputed, from the 16th century, Europeans visiting the Caribbean region identified the South Sea as opposed to the North Sea. The Caribbean Sea had been unknown to the populations of Eurasia until 1492, at that time the Western Hemisphere in general was unknown to Europeans. Following the discovery of the islands by Columbus, the area was colonised by several Western cultures. As of 2015 the area is home to 22 island territories, the International Hydrographic Organization defines the limits of the Caribbean Sea as follows, On the North. In the Windward Channel – a line joining Caleta Point and Pearl Point in Haïti, in the Mona Passage – a line joining Cape Engano and the extreme of Agujereada in Puerto Rico. From Galera Point through Trinidad to Galeota Point and thence to Baja Point in Venezuela, note that, although Barbados is an island on the same continental shelf, it is considered to be in the Atlantic Ocean rather than the Caribbean Sea. The Caribbean Sea is an oceanic sea largely situated on the Caribbean Plate, the Caribbean Sea is separated from the ocean by several island arcs of various ages. The youngest stretches from the Lesser Antilles to the Virgin Islands to the north east of Trinidad, the larger islands in the northern part of the sea Cuba, Hispaniola, Jamaica and Puerto Rico lie on an older island arc. The geological age of the Caribbean Sea is estimated to be between 160 and 180 million years and was formed by a fracture that split the supercontinent called Pangea in the Mesozoic Era. It is assumed the proto-caribbean basin existed in the Devonian period, in the early Carboniferous movement of Gondwana to the north and its convergence with the Euramerica basin decreased in size. The next stage of the Caribbean Seas formation began in the Triassic, powerful rifting led to the formation of narrow troughs, stretching from modern Newfoundland to the west coast of the Gulf of Mexico which formed siliciclastic sedimentary rocks. In the early Jurassic due to powerful marine transgression, water broke into the present area of the Gulf of Mexico creating a vast shallow pool, the emergence of deep basins in the Caribbean occurred during the Middle Jurassic rifting. The emergence of these marked the beginning of the Atlantic Ocean
6.
Belize
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Belize, formerly British Honduras, is an independent country on the eastern coast of Central America. Belize is bordered on the north by Mexico, on the south and west by Guatemala and its mainland is about 290 km long and 110 km wide. Belize has an area of 22,800 square kilometres and a population of 368,310 and it has the lowest population density in Central America. The countrys population growth rate of 1. 87% per year is the second highest in the region, Belizes abundance of terrestrial and marine species and its diversity of ecosystems gives it a key place in the globally significant Mesoamerican Biological Corridor. Belize has a society, composed of many cultures and languages that reflect its rich history. English is the language of Belize, with Belizean Kriol being the unofficial language. Over half the population is multilingual, with Spanish being the second most common spoken language, Belize is considered a Central American and Caribbean nation with strong ties to both the Latin American and Caribbean regions. Belize is a Commonwealth realm, with Queen Elizabeth II as its monarch, Belize is known for its September Celebrations, its extensive coral reefs, and punta music. The origin of the name Belize remains unclear, the earliest known record of the name appears in the journal of the Dominican priest Fray José Delgado, dating to 1677. Delgado recorded the names of three rivers that he crossed while travelling north along the Caribbean coast, Rio Soyte, Rio Xibum. The names of these waterways, which correspond to the Sittee River, Sibun River and it is likely that Delgados Balis was actually the Mayan word belix, meaning muddy-watered. Others have suggested that the name derives from a Spanish pronunciation of the name of the Scottish buccaneer Peter Wallace, there is no proof that Wallace settled in this area and some scholars have characterized this claim as a myth. Writers and historians have suggested other possible etymologies, including postulated French. Many aspects of this culture persist in the area despite nearly 500 years of European domination, prior to about 2500 BC, some hunting and foraging bands settled in small farming villages, they later domesticated crops such as corn, beans, squash, and chili peppers. A profusion of languages and subcultures developed within the Maya core culture, between about 2500 BC and 250 AD, the basic institutions of Maya civilisation emerged. The peak of this occurred during the classic period, which began about 250 AD. The Maya civilisation spread across what is now Belize around 1500 BC, the recorded history of the middle and southern regions is dominated by Caracol, an urban political centre that may have supported over 140,000 people. North of the Maya Mountains, the most important political centre was Lamanai, in the late Classic Era of Maya civilisation, as many as 1 million people may have lived in the area that is now Belize
7.
Equator
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The Equator usually refers to an imaginary line on the Earths surface equidistant from the North Pole and South Pole, dividing the Earth into the Northern Hemisphere and Southern Hemisphere. The Equator is about 40,075 kilometres long, some 78. 7% lies across water and 21. 3% over land, other planets and astronomical bodies have equators similarly defined. Generally, an equator is the intersection of the surface of a sphere with the plane that is perpendicular to the spheres axis of rotation. The latitude of the Earths equator is by definition 0° of arc, the equator is the only line of latitude which is also a great circle — that is, one whose plane passes through the center of the globe. The plane of Earths equator when projected outwards to the celestial sphere defines the celestial equator, in the cycle of Earths seasons, the plane of the equator passes through the Sun twice per year, at the March and September equinoxes. To an observer on the Earth, the Sun appears to travel North or South over the equator at these times, light rays from the center of the Sun are perpendicular to the surface of the Earth at the point of solar noon on the Equator. Locations on the Equator experience the quickest sunrises and sunsets because the sun moves nearly perpendicular to the horizon for most of the year. The Earth bulges slightly at the Equator, the diameter of the Earth is 12,750 kilometres. Because the Earth spins to the east, spacecraft must also launch to the east to take advantage of this Earth-boost of speed, seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earths axis relative to the plane of revolution. During the year the northern and southern hemispheres are inclined toward or away from the sun according to Earths position in its orbit, the hemisphere inclined toward the sun receives more sunlight and is in summer, while the other hemisphere receives less sun and is in winter. At the equinoxes, the Earths axis is not tilted toward the sun, instead it is perpendicular to the sun meaning that the day is about 12 hours long, as is the night, across the whole of the Earth. Near the Equator there is distinction between summer, winter, autumn, or spring. The temperatures are usually high year-round—with the exception of high mountains in South America, the temperature at the Equator can plummet during rainstorms. In many tropical regions people identify two seasons, the wet season and the dry season, but many places close to the Equator are on the oceans or rainy throughout the year, the seasons can vary depending on elevation and proximity to an ocean. The Equator lies mostly on the three largest oceans, the Pacific Ocean, the Atlantic Ocean, and the Indian Ocean. The highest point on the Equator is at the elevation of 4,690 metres, at 0°0′0″N 77°59′31″W and this is slightly above the snow line, and is the only place on the Equator where snow lies on the ground. At the Equator the snow line is around 1,000 metres lower than on Mount Everest, the Equator traverses the land of 11 countries, it also passes through two island nations, though without making a landfall in either. Starting at the Prime Meridian and heading eastwards, the Equator passes through, Despite its name, however, its island of Annobón is 155 km south of the Equator, and the rest of the country lies to the north
8.
Prime meridian
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A prime meridian is a meridian in a geographical coordinate system at which longitude is defined to be 0°. Together, a meridian and its antimeridian form a great circle. This great circle divides the sphere, e. g. the Earth, if one uses directions of East and West from a defined prime meridian, then they can be called Eastern Hemisphere and Western Hemisphere. The most widely used modern meridian is the IERS Reference Meridian and it is derived but deviates slightly from the Greenwich Meridian, which was selected as an international standard in 1884. The notion of longitude was developed by the Greek Eratosthenes in Alexandria, and Hipparchus in Rhodes, but it was Ptolemy who first used a consistent meridian for a world map in his Geographia. The main point is to be comfortably west of the tip of Africa as negative numbers were not yet in use. His prime meridian corresponds to 18°40 west of Winchester today, at that time the chief method of determining longitude was by using the reported times of lunar eclipses in different countries. Ptolemys Geographia was first printed with maps at Bologna in 1477, but there was still a hope that a natural basis for a prime meridian existed. The Tordesillas line was settled at 370 leagues west of Cape Verde. This is shown in Diogo Ribeiros 1529 map, in 1541, Mercator produced his famous 41 cm terrestrial globe and drew his prime meridian precisely through Fuertaventura in the Canaries. His later maps used the Azores, following the magnetic hypothesis, but by the time that Ortelius produced the first modern atlas in 1570, other islands such as Cape Verde were coming into use. In his atlas longitudes were counted from 0° to 360°, not 180°W to 180°E as is usual today and this practice was followed by navigators well into the 18th century. In 1634, Cardinal Richelieu used the westernmost island of the Canaries, Ferro, 19°55 west of Paris, the geographer Delisle decided to round this off to 20°, so that it simply became the meridian of Paris disguised. In the early 18th century the battle was on to improve the determination of longitude at sea, between 1765 and 1811, Nevil Maskelyne published 49 issues of the Nautical Almanac based on the meridian of the Royal Observatory, Greenwich. Maskelynes tables not only made the lunar method practicable, they made the Greenwich meridian the universal reference point. In 1884, at the International Meridian Conference in Washington, D. C.22 countries voted to adopt the Greenwich meridian as the meridian of the world. The French argued for a line, mentioning the Azores and the Bering Strait. In October 1884 the Greenwich Meridian was selected by delegates to the International Meridian Conference held in Washington, united States to be the common zero of longitude and standard of time reckoning throughout the world
9.
Pacific Ocean
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The Pacific Ocean is the largest and deepest of the Earths oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south and is bounded by Asia and Australia in the west, the Mariana Trench in the western North Pacific is the deepest point in the world, reaching a depth of 10,911 metres. Both the center of the Water Hemisphere and the Western Hemisphere are in the Pacific Ocean, the oceans current name was coined by Portuguese explorer Ferdinand Magellan during the Spanish circumnavigation of the world in 1521, as he encountered favourable winds on reaching the ocean. He called it Mar Pacífico, which in both Portuguese and Spanish means peaceful sea, important human migrations occurred in the Pacific in prehistoric times. Long-distance trade developed all along the coast from Mozambique to Japan, trade, and therefore knowledge, extended to the Indonesian islands but apparently not Australia. By at least 878 when there was a significant Islamic settlement in Canton much of trade was controlled by Arabs or Muslims. In 219 BC Xu Fu sailed out into the Pacific searching for the elixir of immortality, from 1404 to 1433 Zheng He led expeditions into the Indian Ocean. The east side of the ocean was discovered by Spanish explorer Vasco Núñez de Balboa in 1513 after his expedition crossed the Isthmus of Panama and he named it Mar del Sur because the ocean was to the south of the coast of the isthmus where he first observed the Pacific. Later, Portuguese explorer Ferdinand Magellan sailed the Pacific East to West on a Castilian expedition of world circumnavigation starting in 1519, Magellan called the ocean Pacífico because, after sailing through the stormy seas off Cape Horn, the expedition found calm waters. The ocean was often called the Sea of Magellan in his honor until the eighteenth century, sailing around and east of the Moluccas, between 1525 and 1527, Portuguese expeditions discovered the Caroline Islands, the Aru Islands, and Papua New Guinea. In 1542–43 the Portuguese also reached Japan, in 1564, five Spanish ships consisting of 379 explorers crossed the ocean from Mexico led by Miguel López de Legazpi and sailed to the Philippines and Mariana Islands. The Manila galleons operated for two and a half centuries linking Manila and Acapulco, in one of the longest trade routes in history, Spanish expeditions also discovered Tuvalu, the Marquesas, the Cook Islands, the Solomon Islands, and the Admiralty Islands in the South Pacific. In the 16th and 17th century Spain considered the Pacific Ocean a Mare clausum—a sea closed to other naval powers, as the only known entrance from the Atlantic the Strait of Magellan was at times patrolled by fleets sent to prevent entrance of non-Spanish ships. On the western end of the Pacific Ocean the Dutch threatened the Spanish Philippines, Spain also sent expeditions to the Pacific Northwest reaching Vancouver Island in southern Canada, and Alaska. The French explored and settled Polynesia, and the British made three voyages with James Cook to the South Pacific and Australia, Hawaii, and the North American Pacific Northwest, one of the earliest voyages of scientific exploration was organized by Spain in the Malaspina Expedition of 1789–1794. It sailed vast areas of the Pacific, from Cape Horn to Alaska, Guam and the Philippines, New Zealand, Australia, and the South Pacific. Growing imperialism during the 19th century resulted in the occupation of much of Oceania by other European powers, and later, Japan, in Oceania, France got a leading position as imperial power after making Tahiti and New Caledonia protectorates in 1842 and 1853 respectively. After navy visits to Easter Island in 1875 and 1887, Chilean navy officer Policarpo Toro managed to negotiate an incorporation of the island into Chile with native Rapanui in 1888, by occupying Easter Island, Chile joined the imperial nations
10.
Coral reef
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Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures secreted by corals. Coral reefs are built by colonies of tiny animals found in waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups, the polyps belong to a group of animals known as Cnidaria, which also includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons which support, most reefs grow best in warm, shallow, clear, sunny and agitated waters. Often called rainforests of the sea, shallow coral reefs form some of the most diverse ecosystems on Earth, paradoxically, coral reefs flourish even though they are surrounded by ocean waters that provide few nutrients. They are most commonly found at depths in tropical waters. Coral reefs deliver ecosystem services to tourism, fisheries and shoreline protection, the annual global economic value of coral reefs is estimated between US$29. 8-375 billion. However, coral reefs are fragile ecosystems, partly because they are sensitive to water temperature. Most of the coral reefs we can see today were formed after the last glacial period when melting ice caused the sea level to rise and this means that most modern coral reefs are less than 10,000 years old. As communities established themselves on the shelves, the reefs grew upwards, Reefs that rose too slowly could become drowned reefs. They are covered by so much water there was insufficient light. Coral reefs are found in the sea away from continental shelves, around oceanic islands. The vast majority of islands are volcanic in origin. The few exceptions have tectonic origins where plate movements have lifted the deep ocean floor on the surface. In 1842 in his first monograph, The Structure and Distribution of Coral Reefs, Charles Darwin set out his theory of the formation of atoll reefs and he theorized uplift and subsidence of the Earths crust under the oceans formed the atolls. Darwin’s theory sets out a sequence of three stages in atoll formation and it starts with a fringing reef forming around an extinct volcanic island as the island and ocean floor subsides. As the subsidence continues, the reef becomes a barrier reef. Darwin predicted that underneath each lagoon would be a bed rock base, where the level of the underlying earth allows, the corals grow around the coast to form what he called fringing reefs, and can eventually grow out from the shore to become a barrier reef
11.
Island
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An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, an island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, an island may be described as such, despite the presence of an artificial land bridge. Example, Singapore and its causeway, or the various Dutch delta islands, there are two main types of islands in the sea, continental and oceanic. The word island derives from Middle English iland, from Old English igland, Old English ieg is actually a cognate of Swedish ö and German Aue, and related to Latin aqua. There is a difference between islands and continents in terms of geology, continents sit on continental lithosphere which is part of tectonic plates floating high on Earths mantle. Oceanic crust is also part of tectonic plates, but it is denser than continental lithosphere, Islands are either extensions of the oceanic crust or geologically they are part of some continent sitting on continental lithosphere. This holds true for Australia, which sits on its own continental lithosphere, continental islands are bodies of land that lie on the continental shelf of a continent. A special type of island is the microcontinental island, which is created when a continent is rifted. Examples are Madagascar and Socotra off Africa, the Kerguelen Islands, New Caledonia, New Zealand, another subtype is an island or bar formed by deposition of tiny rocks where water current loses some of its carrying capacity. While some are transitory and may disappear if the volume or speed of the current changes, others are stable, oceanic islands are islands that do not sit on continental shelves. The vast majority are volcanic in origin, such as Saint Helena in the South Atlantic Ocean, the few oceanic islands that are not volcanic are tectonic in origin and arise where plate movements have lifted up the ocean floor above the surface. Examples are Saint Peter and Paul Rocks in the Atlantic Ocean, one type of volcanic oceanic island is found in a volcanic island arc. These islands arise from volcanoes where the subduction of one plate under another is occurring, examples are the Aleutian Islands, the Mariana Islands, and most of Tonga in the Pacific Ocean. The only examples in the Atlantic Ocean are some of the Lesser Antilles, another type of volcanic oceanic island occurs where an oceanic rift reaches the surface. There are two examples, Iceland, which is the second largest volcanic island, and Jan Mayen. A third type of oceanic island is formed over volcanic hotspots. A hotspot is more or less stationary relative to the tectonic plate above it
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This article incorporates public domain material from the Library of Congress Country Studies website http://lcweb2.loc.gov/frd/cs/.
This article incorporates 
