Africa |
Africa is the world's second-largest and second most-populous continent, after Asia. At about 30,221,532 km² (11,668,545 mi²) including adjacent islands, it covers 6.0% of the Earth's total surface area, and 20.4% of the total land area. With more than 900,000,000 people (as of 2005) in 61 territories, it accounts for about 14% of the world's human population. The continent is surrounded by the Mediterranean Sea to the north, the Suez Canal and the Red Sea to the northeast, the Indian Ocean to the southeast, and the Atlantic Ocean to the west. There are 46 countries including Madagascar, and 53 including all the island groups.
Africa, particularly central eastern Africa, is widely regarded within the scientific community to be the origin of humans and the Hominidae tree, as evidenced by the discovery of the earliest Hominids, as well as later ones that have been dated to around 7 million years ago including Sahelanthropus tchadensis, Africanus, Homo Erectus, with the earliest humans being dated to ca. 200,000 years ago, according to this view.
Africa straddles the equator and encompasses numerous climate areas; it is the only continent to stretch from the northern temperate to southern temperate zones. Because of the lack of natural regular precipitation and irrigation as well as glaciers or mountain aquifer systems, there is no natural moderating effect on the climate except near the coasts.
The climate of Africa ranges from tropical to subarctic on its highest peaks. Its northern half is primarily desert or arid, while its central and southern areas contain both savanna plains and very dense jungle (rainforest) regions. In between, there is a convergence where vegetation patterns such as sahel, and steppe dominate.
Africa boasts perhaps the world's largest combination of density and "range of freedom" of wild animal populations and diversity, with wild populations of large carnivores (such as lions, hyenas, and cheetahs) and herbivores (such as buffalo, deer, elephants, camels, and giraffes) ranging freely on primarily open non-private plains. It is also home to a variety of jungle creatures (including snakes and primates) and aquatic life (including crocodiles and amphibians).
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North America |
North America is a continent in the Earth's northern hemisphere and (chiefly) western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the south and west by the North Pacific Ocean; South America lies to the southeast, connected to North America by the Isthmus of Panama. It covers an area of about 24,490,000 square kilometres (9,450,000 sq mi), about 4.8% of the planet's surface or about 16.4% of its land area. As of October 2006, its population was estimated at over 514,600,000. It is the third-largest continent in area, following Asia and Africa, and is fourth in population after Asia, Africa, and Europe. North and South America are collectivelly known as the Americas.
North America occupies the northern portion of the landmass generally referred to as the New World, the Western Hemisphere, the Americas, or simply America (which is sometimes considered a single continent and North America a subcontinent). North America's only land connection is to South America at the narrow Isthmus of Panama. (Geopolitically, all of Panama—including the segment east of the Panama Canal in the isthmus—is often considered a part of North America alone.) According to some authorities, North America begins not at the Isthmus of Panama but at the Isthmus of Tehuantepec, Mexico with the intervening region called Central America (or Middle America if the Caribbean is included) and resting on the Caribbean Plate. Before the Central American isthmus was raised, the region had been underwater. The islands of the West Indies delineate a submerged former land bridge, which had connected North America and South America via Florida and Venezuela.
The continental coastline is long and irregular. The Gulf of Mexico is the largest body of water indenting the continent, followed by Hudson Bay. Others include the Gulf of Saint Lawrence and the Gulf of California.
There are numerous islands off the continent’s coasts: principally, the Arctic Archipelago, the Greater and Lesser Antilles, the Alexander Archipelago, and the Aleutian Islands. Greenland, a Danish self-governing island and the world's largest, is on the same tectonic plate (the North American Plate) and is part of North America geographically. Bermuda is not part of the Americas, but is an oceanic island which was formed on the fissure of the Mid-Atlantic Ridge over 100 million years ago. The nearest landmass to it is Cape Hatteras, North Carolina, and it is often thought of as part of North America, especially given its historical political and cultural ties to Virginia and other parts of the continent. |
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Asia |
Asia is the world's largest and most populous continent. It covers 8.6% of the Earth's total surface area (or 29.4% of its land area) and, with almost 4 billion people, it contains more than 60% of the world's current human population.
Chiefly in the eastern and northern hemispheres, Asia is traditionally defined as part of the landmass of Africa-Eurasia – with the western portion of the latter occupied by Europe – lying east of the Suez Canal, east of the Ural Mountains, and south of the Caucasus Mountains and the Caspian and Black Seas. It is bounded to the east by the Pacific Ocean, to the south by the Indian Ocean, and to the north by the Arctic Ocean.
Given its size and diversity, Asia – a toponym dating back to classical antiquity – is. more a cultural concept incorporating a number of regions and peoples than a homogeneous, physical entity
In the far northeast of Asia, Siberia is separated from North America by the Bering Strait. Asia is bounded on the south by the Indian Ocean (specifically, from west to east, the Gulf of Aden, Arabian Sea, and Bay of Bengal); on the east by the waters of the Pacific (including, counterclockwise, the South China Sea, East China Sea, Yellow Sea, Sea of Japan, Sea of Okhotsk, and Bering Sea); and on the north by the Arctic Ocean. Australia (or Oceania) is to the southeast.
Some geographers do not consider Asia and Europe to be separate continents, as there is no logical physical separation between them. Physiographically, Asia is the major eastern constituent of the continent of Eurasia – with Europe being a northwestern peninsula of the landmass – or of Africa-Eurasia: geologically, Asia, Europe, and Africa comprise a single continuous landmass (save the Suez Canal) and share a common continental shelf. Almost all of Europe and most of Asia sit atop the Eurasian Plate, adjoined on the south by the Arabian and Indian Plates, and with much of Siberia on the North American Plate.
In geography, there are two schools of thought. One school follows historical convention and treats Europe and Asia as different continents, categorizing subregions within them for more detailed analysis. The other school equates the word "continent" with a geographical region when referring to Europe, and use the term "region" to describe Asia in terms of physiography. Since, in linguistic terms, "continent" implies a distinct landmass, it is becoming increasingly common to substitute the term "region" for "continent" to avoid the problem of disambiguation altogether.
Given the scope and diversity of the landmass, it is sometimes not even clear exactly what "Asia" consists of. Some definitions exclude Turkey, the Middle East, Central Asia, and Russia while only considering the Far East, Southeast Asia and the Indian subcontinent to compose Asia, especially in the United States after World War II. The term is sometimes used more strictly in reference to the Asia-Pacific region, which does not include the Middle East or Russia, but does include islands in the Pacific Ocean — a number of which may also be considered part of Australasia or Oceania, although Pacific Islanders are commonly not considered Asian. |
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Europe |
Europe is one of the seven traditional continents of the Earth. Physically and geologically, Europe is the westernmost peninsula of Eurasia, west of Asia. Europe is bounded to the north by the Arctic Ocean, to the west by the Atlantic Ocean, to the south by the Mediterranean Sea, to the southeast by the Caucasus Mountains and the Black Sea and the waterways connecting the Black Sea to the Mediterranean. To the east, Europe is generally divided from Asia by the water divide of the Ural Mountains, the Ural River, and by the Caspian Sea.
Europe is the world's second-smallest continent in terms of area, covering about 10,180,000 square kilometres (3,930,000 sq mi) or 2.0% of the Earth's surface. The only continent smaller than Europe is Australia. In terms of population, it is the third-largest continent (after Asia and Africa) with a population of 710,000,000 or about 11% of the world's population. However, the term continent can refer to a cultural and political distinction or a physiographic one, leading to various perspectives about Europe's precise borders, area, and population. Russia is Europe's largest country by area and population, the Vatican being the smallest. Europe is the birthplace of the European Union, a union of twenty-seven independent states based on the European Communities and founded to enhance political, economic and social co-operation and integration.
Having lived side-by-side with agricultural peoples for millennia, Europe's animals and plants have been profoundly affected by the presence and activities of man. With the exception of Scandinavia and northern Russia, few areas of untouched wilderness are currently found in Europe, except for various national parks.
The main natural vegetation cover in Europe is forest. The conditions for growth are very favourable. In the north, the Gulf Stream and North Atlantic Drift warm the continent. Southern Europe could be described as having a warm, but mild climate. There are frequent summer droughts in this region. Mountain ridges also affect the conditions. Some of these (Alps, Pyrenees) are oriented east-west and allow the wind to carry large masses of water from the ocean in the interior. Others are oriented south-north (Scandinavian Mountains, Dinarides, Carpathians, Apennines) and because the rain falls primarily on the side of mountains that is oriented towards sea, forests grow well on this side, while on the other side, the conditions are much less favourable. Few corners of mainland Europe have not been grazed by livestock at some point in time, and the cutting down of the pre-agricultural forest habitat caused disruption to the original plant and animal ecosystems.
Eighty to ninety per cent of Europe was once covered by forest. It stretched from the Mediterranean Sea to the Arctic Ocean. Though over half of Europe's original forests disappeared through the centuries of deforestation, Europe still has over one quarter of its land area as forest, such as the taiga of Scandinavia and Russia, mixed rainforests of the Caucasus and the Cork oak forests in the western Mediterranean. During recent times, deforestation has been slowed and many trees have been planted. However, in many cases monoculture plantations of conifers have replaced the original mixed natural forest, because these grow quicker. The plantations now cover vast areas of land, but offer poorer habitats for many European forest dwelling species which require a mixture of tree species and diverse forest structure. The amount of natural forest in Western Europe is just 2–3% or less, in European Russia 5–10%. The country with the smallest percentage of forested area (excluding the micronations) is Iceland (2%), while the most forested country is Finland(72%).
In temperate Europe, mixed forest with both broadleaf and coniferous trees dominate. The most important species in central and western Europe are beech and oak. In the north, the taiga is a mixed spruce-pine-birch forest; further north within Russia and extreme northern Scandinavia, the taiga gives way to tundra as the Arctic is approached. In the Mediterranean, many olive trees have been planted, which are very well adapted to its arid climate; Mediterranean Cypress is also widely planted in southern Europe. The semi-arid Mediterranean region hosts much scrub forest. A narrow east-west tongue of Eurasian grassland (the steppe) extends eastwards from Ukraine and southern Russia and ends in Hungary and traverses into taiga to the north. |
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Oceania |
Oceania (sometimes Oceanica) is a geographical, often geopolitical, region consisting of numerous lands—mostly islands and usually including Australia—in the Pacific Ocean and vicinity. The exact scope of Oceania is defined variously, with interpretations normally including Australia, New Zealand, New Guinea, and various islands of the Malay Archipelago. The term is also used by numerous authors and in many languages to define one of the continents.
Originally coined by the French explorer Dumont d'Urville in 1831, Oceania has been traditionally divided into Micronesia, Melanesia, Polynesia, and Australasia. As with any region, however, interpretations vary; increasingly, geographers and scientists divide Oceania into Near Oceania and Remote Oceania.
Most of Oceania consists of small island nations. Australia is the only continental country, by some definitions. Indonesia has land borders with Papua New Guinea, East Timor, and Malaysia.
Oceania is one of eight terrestrial ecozones, which constitute the major ecological regions of the planet. The Oceania ecozone includes all of Micronesia, Fiji, and all of Polynesia except New Zealand. New Zealand, along with New Guinea and nearby islands, Australia, the Solomon Islands, Vanuatu, and New Caledonia, constitute the separate Australasia ecozone. |
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South America |
South America is a continent of the Americas, situated entirely in the western hemisphere and mostly in the southern hemisphere. It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean; North America and the Caribbean Sea lie to the northwest.
South America was named in 1507 by cartographs Martin Waldseemüller and Matthias Ringmann after Amerigo Vespucci, who was the first European to suggest that the Americas were not the East Indies, but a New World unknown to Europeans.
South America has an area of 17,840,000 square kilometres (6,890,000 sq mi), or almost 3.5% of the Earth's surface. As of 2005, its population was estimated at more than 371,000,000. South America ranks fourth in area (after Asia, Africa, and North America) and fifth in population (after Asia, Africa, Europe, and North America).
South America comprises the major southern portion of the landmass generally referred to as the New World, the Western Hemisphere, the Americas, or simply America (which is sometimes considered a single continent and South America a subcontinent). It is south and east of the Panama Canal, which transects the Isthmus of Panama. Geologically, almost all of mainland South America sits on the South American Plate. Geopolitically, all of Panama – including the segment east of the Panama Canal in the isthmus – is often considered a part of North America alone and among the countries of Central America.
Geologically, the continent became attached to North America only recently with the formation of the Isthmus of Panama approximately 3 million years ago, which resulted in the Great American Interchange. The Andes, likewise a comparatively young and seismically restless mountain range, run down the western edge of the continent; the land to the east of the Andes is largely tropical rainforest, the vast Amazon River basin. The continent also contains drier regions such as East Patagonia and the extremely arid Atacama Desert.
The South American continent also includes various islands, many of which belong to countries on the continent. Many of the islands of the Caribbean (or West Indies) – e.g., the Leeward and Lesser Antilles – sit atop the Caribbean Plate, a tectonic plate with a diffuse topography. The islands of Aruba, Barbados, Trinidad, and Tobago sit on the northerly South American continental shelf. The Netherlands Antilles and the federal dependencies of Venezuela lie along the northerly South American. Geopolitically, the island states and overseas territories of the Caribbean are generally grouped as a part or subregion of North America. The South American nations that border the Caribbean Sea – including Colombia, Venezuela, Guyana, Suriname, and French Guiana – are also known as Caribbean South America. Other islands are the Galapagos, Easter Island (in Oceania but belongs to Chile), Robinson Crusoe Island, Chiloé Island, Tierra del Fuego and the Falklands Islands.
South America is home to the world's highest waterfall, Angel Falls in Venezuela, the largest river (by volume), the Amazon River, the longest mountain range, the Andes, the driest desert, Atacama Desert, the largest rainforest, the Amazon Rainforest, the highest railroad, Ticlio Peru, the highest capital city, La Paz, Bolivia, the highest commercially navigable lake in the world, Lake Titicaca, and the world's southernmost town, Puerto Toro, Chile. |
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