Plateau

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Satellite image of the Tibetan Plateau between the Himalayan mountains to the south and the Taklamakan Desert to the north Himalaya 85.30820E 32.11063N.jpg
Satellite image of the Tibetan Plateau between the Himalayan mountains to the south and the Taklamakan Desert to the north

In geology and physical geography, a plateau ( /pləˈt/ , /plæˈt/ , or /ˈplæt/ ; French:  [pla.to] ; plural plateaus or plateaux [1] [2] ), also called a high plain or a tableland , is an area of a highland, usually consisting of relatively flat terrain, that is raised significantly above the surrounding area, often with one or more sides with deep hills. Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, and erosion by water and glaciers. Plateaus are classified according to their surrounding environment as intermontane, piedmont, or continental. A few plateaus may have a small flat top while others have wide ones.

Contents

Formation

Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, and erosion by water and glaciers.

Volcanic

Volcanic plateaus are produced by volcanic activity. The Columbia Plateau in the northwestern United States is an example. They may be formed by upwelling of volcanic magma or extrusion of lava.

The Pajarito Plateau in New Mexico is an example of a volcanic plateau. Pajarito Plateau.jpg
The Pajarito Plateau in New Mexico is an example of a volcanic plateau.

The underlining mechanism in forming plateaus from upwelling starts when magma rises from the mantle, causing the ground to swell upward. In this way, large, flat areas of rock are uplifted to form a plateau. For plateaus formed by extrusion, the rock is built up from lava spreading outward from cracks and weak areas in the crust.

Erosion

Plateaus can also be formed by the erosional processes of glaciers on mountain ranges, leaving them sitting between the mountain ranges. Water can also erode mountains and other landforms down into plateaus. Dissected plateaus are highly eroded plateaus cut by rivers and broken by deep narrow valleys. Computer modeling studies suggest that high[ clarification needed ] plateaus may also be partially a result from the feedback between tectonic deformation and dry climatic conditions created at the lee side of growing orogens. [3]

Classification

Plateaus are classified according to their surrounding environment.

Large plateaus

Asia

The largest and highest plateau in the world is the Tibetan Plateau, sometimes metaphorically described as the "Roof of the World", which is still being formed by the collisions of the Indo-Australian and Eurasian tectonic plates. The Tibetan plateau covers approximately 2,500,000 km2 (970,000 sq mi), at about 5,000 m (16,000 ft) above sea level. The plateau is sufficiently high to reverse the Hadley cell convection cycles and to drive the monsoons of India towards the south.

The second-highest plateau is the Deosai Plateau of the Deosai National Park (also known as Deoasai Plains) at an average elevation of 4,114 m (13,497 ft). It is located in the Astore and Skardu districts of Gilgit-Baltistan, in northern Pakistan. Deosai means 'the land of giants'. The park protects an area of 3,000 km2 (1,200 sq mi). It is known for its rich flora and fauna of the Karakoram-West Tibetan Plateau alpine steppe ecoregion. In spring it is covered by sweeps of wildflowers and a wide variety of butterflies. The highest point in Deosai is Deosai Lake, or Sheosar Lake from the Shina language meaning "Blind lake" (Sheo – Blind, Sar – lake) near the Chilim Valley. The lake lies at an elevation of 4,142 m (13,589 ft), one of the highest lakes in the world, and is 2.3 km (1.4 mi) long, 1.8 km (1.1 mi) wide, and 40 m (130 ft) deep on average.

Hardangervidda, the largest plateau in Europe Hardangervidda 1986.jpg
Hardangervidda, the largest plateau in Europe
Bogota, Colombia is located in a high plateau, over 8,600 ft (2,600 m) high Bogota Centro.jpg
Bogotá, Colombia is located in a high plateau, over 8,600 ft (2,600 m) high

Some other major plateaus in Asia are: Najd in the Arabian Peninsula elevation 762 to 1,525 m (2,500 to 5,003 ft), Armenian Highlands (≈400,000 km2 (150,000 sq mi), elevation 900–2,100 metres (3,000–6,900 ft)), Iranian plateau (≈3,700,000 km2 (1,400,000 sq mi), elevation 300–1,500 metres (980–4,920 ft)), Anatolian Plateau, Mongolian Plateau (≈2,600,000 km2 (1,000,000 sq mi), elevation 1,000–1,500 metres (3,300–4,900 ft)), and the Deccan Plateau (≈1,900,000 km2 (730,000 sq mi), elevation 300–600 metres (980–1,970 ft)).

Antarctica

Another very large plateau is the icy Antarctic Plateau, which is sometimes referred to as the Polar Plateau, home to the geographic South Pole and the Amundsen-Scott South Pole Station, which covers most of East Antarctica where there are no known mountains but rather 3,000 m (9,800 ft) high of superficial ice and which spreads very slowly toward the surrounding coastline through enormous glaciers. This polar ice cap is so massive that the echolocation sound measurements of ice thickness have shown that large parts of the Antarctic "dry land" surface have been pressed below sea level. Thus, if that same ice cap were suddenly removed, the large areas of the frozen white continent would be flooded by the surrounding Antarctic Ocean or Southern Ocean. On the other hand, were the ice cap melts away too gradually, the surface of the land beneath it would gradually rebound away through isostasy from the center of the Earth and that same land would ultimately rise above sea level.

North America

A large plateau in North America is the Colorado Plateau, which covers about 337,000 km2 (130,000 sq mi) in Colorado, Utah, Arizona and New Mexico. [4]

In northern Arizona and southern Utah the Colorado Plateau is bisected by the Colorado River and the Grand Canyon. How this came to be is that over 10 million years ago, a river was already there, though not necessarily on exactly the same course. Then, subterranean geological forces caused the land in that part of North America to gradually rise by about a centimeter per year for millions of years. An unusual balance occurred: the river that would become the Colorado River was able to erode into the crust of the Earth at a nearly equal rate to the uplift of the plateau. Now, millions of years later, the North Rim of the Grand Canyon is at an elevation of about 2,450 m (8,040 ft) above sea level, and the South Rim of the Grand Canyon is about 2,150 m (7,050 ft) above sea level. At its deepest, the Colorado River is about 1,830 m (6,000 ft) below the level of the North Rim.

Another high altitude plateau in North America is the Mexican Plateau. With an area of 601,882 km2 (232,388 sq mi) and average height of 1,825 m, it is the home of more than 70 million people.

South America

A tepui ( /ˈtɛpwi/ ), or tepuy (Spanish:  [teˈpui] ), is a table-top mountain or mesa found in the Guiana Highlands of South America, especially in Venezuela and western Guyana. The word tepui means "house of the gods" in the native tongue of the Pemon, the indigenous people who inhabit the Gran Sabana.

Tepuis can be considered minute plateaus and tend to be found as isolated entities rather than in connected ranges, which makes them the host of a unique array of endemic plant and animal species. Some of the most outstanding tepuis are Neblina, Autana, Auyan and Mount Roraima. They are typically composed of sheer blocks of Precambrian quartz arenite sandstone that rise abruptly from the jungle, giving rise to spectacular natural scenery. Auyantepui is the source of Angel Falls, the world's tallest waterfall.

The Colombian capital city of Bogota sits on an Andean plateau known as the Altiplano Cundiboyacense roughly the size of Switzerland. Averaging a height of 2,600 m (8,500 ft) above sea level, this northern Andean plateau is situated in the country's eastern range and is divided into three main flat regions: the Bogotá savanna, the valleys of Ubaté and Chiquinquirá, and the valleys of Duitama and Sogamoso.

Road to the ALMA's Operations Support Facility and then on further to the Chajnantor Plateau at 5000 meters above sea level. The Road to the Stars.jpg
Road to the ALMA’s Operations Support Facility and then on further to the Chajnantor Plateau at 5000 meters above sea level.

The parallel Sierra of Andes delimit one of the world highest plateaux: the Altiplano, (Spanish for "high plain"), Andean Plateau or Bolivian Plateau. It lies in west-central South America, where the Andes are at their widest, is the most extensive area of high plateau on Earth outside of Tibet. The bulk of the Altiplano lies within Bolivian and Peruvian territory while its southern parts lie in Chile. The Altiplano plateau hosts several cities like Puno, Oruro, El Alto and La Paz the administrative seat of Bolivia. Northeastern Altiplano is more humid than the Southwestern, the latter of which hosts several salares, or salt flats, due to its aridity. At the Bolivia-Peru border lies Lake Titicaca, the largest lake in South America.

Africa

The highest African plateau is the Ethiopian Highlands which cover the central part of Ethiopia. It forms the largest continuous area of its altitude in the continent, with little of its surface falling below 1500 m (4,921 ft), while the summits reach heights of up to 4550 m (14,928 ft). It is sometimes called the Roof of Africa due to its height and large area.

Another example is the Highveld which is the portion of the South African inland plateau which has an altitude above approximately 1500 m, but below 2100 m, thus excluding the Lesotho mountain regions. It is home to some of largest South-African urban agglomerations.

In Egypt are the Giza Plateau [6] and Galala Mountain, which was once called Gallayat Plateaus, raising 3,300 above sea level. [7]

Oceania

The Western Plateau, part of the Australian Shield, is an ancient craton covering much of the continent's southwest, an area of some 700,000 square kilometres. It has an average elevation of between 305 and 460 m.

The North Island Volcanic Plateau is an area of high land occupying much of the centre of the North Island of New Zealand, with volcanoes, lava plateaus, and crater lakes, the most notable of which is the country's largest lake, Lake Taupo. The plateau stretches approximately 100 km east to west and 130 km north to south. The majority of the plateau is more than 600 m above sea level.

See also

Related Research Articles

Geography of Bolivia

The geography of Bolivia includes the Eastern Andes Mountain Range which bisects Bolivia roughly from north to south. To the east of that mountain chain are lowland plains of the Amazon Basin, and to the west is the Altiplano which is a highland plateau where Lake Titicaca is located. Bolivia's geography has features similar to those of Peru which abuts Bolivia's northwest border; like Bolivia, Peru is bisected from north to south by the Eastern Andes Mountains, and these two countries share Lake Titicaca which is the highest navigable lake on Earth. Unlike Peru, however, Bolivia is one of the two landlocked countries in South America, the other being Paraguay which is located along Bolivia's southeast border.

Guyot An isolated, flat-topped underwater volcano mountain

In marine geology, a guyot, also known as a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than 200 m (660 ft) below the surface of the sea. The diameters of these flat summits can exceed 10 km (6.2 mi). Guyots are most commonly found in the Pacific Ocean, but they have been identified in all the oceans except the Arctic Ocean.

Geology of the Lassen volcanic area

The geology of the Lassen volcanic area presents a record of sedimentation and volcanic activity in the area in and around Lassen Volcanic National Park in Northern California, U.S. The park is located in the southernmost part of the Cascade Mountain Range in the Pacific Northwest region of the United States. Pacific Oceanic tectonic plates have plunged below the North American Plate in this part of North America for hundreds of millions of years. Heat from these subducting plates has fed scores of volcanoes in California, Oregon, Washington and British Columbia over at least the past 30 million years and is also responsible for activities in the Lassen volcanic area.

Parinacota (volcano) Volcano on the border of Chile and Bolivia

Parinacota, Parina Quta or Parinaquta is a dormant stratovolcano on the border of Chile and Bolivia. Together with Pomerape it forms the Nevados de Payachata volcanic chain. Part of the Central Volcanic Zone of the Andes, its summit reaches an elevation of 6,380 metres (20,930 ft) above sea level. The symmetrical cone is capped by a summit crater with widths of 1 kilometre (0.62 mi) or 500 metres (1,600 ft). Farther down on the southern slopes lie three parasitic centres known as the Ajata cones. These cones have generated lava flows. The volcano overlies a platform formed by lava domes and andesitic lava flows.

Heart Peaks mountain massif in British Columbia, Canada

Heart Peaks, originally known as the Heart Mountains, is a mountain massif in the Northern Interior of British Columbia, Canada. It is 90 km (56 mi) northwest of the small community of Telegraph Creek and just southwest of Callison Ranch. With a maximum elevation of 2,012 m (6,601 ft), it rises above the surrounding landscape on the Nahlin Plateau, which is part of the western Stikine Plateau. Heart Peaks has been an area of prospecting since the 1980s with the discovery of precious metals.

Ollagüe mountain shared by Bolivia and Chile

Ollagüe or Ullawi is a massive andesite stratovolcano in the Andes on the border between Bolivia and Chile, within the Antofagasta Region of Chile and the Potosi Department of Bolivia. Part of the Central Volcanic Zone of the Andes, its highest summit is 5,868 metres (19,252 ft) above sea level and features a summit crater that opens to the south. The western rim of the summit crater is formed by a compound of lava domes, the youngest of which features a vigorous fumarole that is visible from afar.

Level Mountain Mountain in Canada

Level Mountain is a massive complex volcano in the Northern Interior of British Columbia, Canada. It is located 50 km (31 mi) north-northwest of Telegraph Creek and 60 km (37 mi) west of Dease Lake on the Nahlin Plateau. With a maximum elevation of 2,166 m (7,106 ft), it is the third highest of five large complexes in an extensive north-south trending volcanic zone. Much of the mountain is gently-sloping; when measured from its base, Level Mountain is about 1,100 m (3,600 ft) tall, slightly taller than its neighbour to the northwest, Heart Peaks. The lower broader half of Level Mountain consists of a shield-like edifice while its upper half has a more steep, jagged profile. Its large summit is dominated by the Level Mountain Range, a small mountain range with prominent peaks cut by deep valleys. These valleys serve as a radial drainage for several small streams that flow from the volcano. Meszah Peak is the only named peak in the Level Mountain Range.

Volcanology of Canada

Volcanology of Canada includes lava flows, lava plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes, and maars, along with examples of more less common volcanic forms such as tuyas and subglacial mounds. It has a very complex volcanological history spanning from the Precambrian eon at least 3.11 billion years ago when this part of the North American continent began to form.

Ilgachuz Range mountain in Canada

The Ilgachuz Range is a name given to an extinct shield volcano in British Columbia, Canada. It is not a mountain range in the normal sense, because it was formed as a single volcano that has been eroded for the past 5 million years. It lies on the Chilcotin Plateau, located some 350 kilometres (220 mi) north-northwest of Vancouver and 30 km north of Anahim Lake. The highest peak of the range is Far Mountain. The range supports a unique grassland ecosystem. This type of grassland has not been seen anywhere else in central and southern British Columbia. The climate is cool and dry; typical of higher elevations of the Interior Plateau.

Maitland Volcano mountain in Canada

Maitland Volcano is a heavily eroded shield volcano in the Northern Interior of British Columbia, Canada. It is 83 km (52 mi) southeast of the small community of Telegraph Creek in what is now the Klappan Range of the northern Skeena Mountains. This multi-vent volcano covered a remarkably large area and was topped by a younger volcanic edifice. Little remains of Maitland Volcano today, limited only to eroded lava flows and distinctive upstanding landforms created when magma hardened within the vents of the volcano.

Silverthrone Caldera Stratovolcano in Canada

The Silverthrone Caldera is a potentially active caldera complex in southwestern British Columbia, Canada, located over 350 kilometres (220 mi) northwest of the city of Vancouver and about 50 kilometres (31 mi) west of Mount Waddington in the Pacific Ranges of the Coast Mountains. The caldera is one of the largest of the few calderas in western Canada, measuring about 30 kilometres (19 mi) long (north-south) and 20 kilometres (12 mi) wide (east-west). Mount Silverthrone, an eroded lava dome on the caldera's northern flank that is 2,864 metres (9,396 ft) high, may be the highest volcano in Canada.

Mount Edziza volcanic complex mountain in Canada

The Mount Edziza volcanic complex is a large and potentially active north-south trending complex volcano in Stikine Country, northwestern British Columbia, Canada, located 38 kilometres (24 mi) southeast of the small community of Telegraph Creek. It occupies the southeastern portion of the Tahltan Highland, an upland area of plateau and lower mountain ranges, lying east of the Boundary Ranges and south of the Inklin River, which is the east fork of the Taku River. As a volcanic complex, it consists of many types of volcanoes, including shield volcanoes, calderas, lava domes, stratovolcanoes, and cinder cones.

Volcanology of Northern Canada

Volcanology of Northern Canada includes hundreds of volcanic areas and extensive lava formations across Northern Canada. The region's different volcano and lava types originate from different tectonic settings and types of volcanic eruptions, ranging from passive lava eruptions to violent explosive eruptions. Northern Canada has a record of very large volumes of magmatic rock called large igneous provinces. They are represented by deep-level plumbing systems consisting of giant dike swarms, sill provinces and layered intrusions.

Volcanic history of the Northern Cordilleran Volcanic Province

The volcanic history of the Northern Cordilleran Volcanic Province presents a record of volcanic activity in northwestern British Columbia, central Yukon and the U.S. state of easternmost Alaska. The volcanic activity lies in the northern part of the Western Cordillera of the Pacific Northwest region of North America. Extensional cracking of the North American Plate in this part of North America has existed for millions of years. Continuation of this continental rifting has fed scores of volcanoes throughout the Northern Cordilleran Volcanic Province over at least the past 20 million years and occasionally continued into geologically recent times.

Tunupa mountain in Potosí Department Bolivia

Tunupa is a dormant volcano in the Potosí Department of southwestern Bolivia.

Cerro Guacha

Cerro Guacha is a Miocene caldera in southwestern Bolivia's Sur Lípez Province. Part of the volcanic system of the Andes, it is considered to be part of the Central Volcanic Zone (CVZ), one of the three volcanic arcs of the Andes, and its associated Altiplano-Puna volcanic complex (APVC). A number of volcanic calderas occur within the latter.

Cerro Bitiche is a volcanic field in Argentina. It is located east of the Central Volcanic Zone away from the volcanic arc within the Altiplano-Puna volcanic complex (APVC), close to Zapaleri volcano.

Los Frailes ignimbrite plateau

Los Frailes is an ignimbrite plateau in Bolivia, between the city of Potosi and the Lake Poopo. It belongs to a group of ignimbrites that exist in the Central Andes and which includes the Altiplano–Puna volcanic complex. The plateau covers a surface of 7,500 square kilometres (2,900 sq mi)–8,500 square kilometres (3,300 sq mi) with about 2,000 cubic kilometres (480 cu mi) of ignimbrite.

Uturuncu stratovolcano

Uturunku is a dormant 6,008 metres (19,711 ft) high volcano in Bolivia with two summit peaks. It consists of a complex of lava domes and lava flows with a total volume of 50–85 cubic kilometres (12–20 cu mi) and bears traces of a former glaciation, even though it does not currently carry glaciers. Volcanic activity took place during the Pleistocene and the last eruption was 250,000 years ago; since then Uturuncu has not erupted but active fumaroles occur in the summit region.

References

  1. "Definition of plateau". American English Dictionary. Merriam-Webster . Retrieved 26 August 2017.
  2. "Definition of plateau". Cambridge English Dictionary . Cambridge University Press . Retrieved 26 August 2017.
  3. Garcia-Castellanos, D., 2007. The role of climate during high plateau formation. Insights from numerical experiments. Earth Planet. Sci. Lett. 257, 372-390, doi:10.1016/j.epsl.2007.02.039 pdf
  4. Leighty, Dr. Robert D. (2001). "Colorado Plateau Physiographic Province". Contract Report. Defense Advanced Research Projects Agency (DOD) Information Sciences Office. Archived from the original on 2004-09-26. Retrieved 2007-12-25.
  5. "The Road to the Stars" . Retrieved 27 July 2015.
  6. The Ibis. 1906. pp. 206–.
  7. Maged S. A. Mikhail; Mark Moussa (2009). Christianity and Monasticism in Wadi Al-Natrun: Essays from the 2002 International Symposium of the Saint Mark Foundation and the Saint Shenouda the Archimandrite Coptic Society. American Univ in Cairo Press. pp. 63–. ISBN   978-977-416-260-2.

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