For other uses see Mountain (disambiguation). The Matterhorn Swiss Alps Five Finger Mountain Azerbaijan

A mountain is a large landform that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill. The adjective montane is used to describe mountainous areas and things associated with them. The study of mountains is called Orography.

Exogeology deals with planetary mountains which in that branch of science are usually called montes (singularmons). The highest mountain on Earth based from sea level is Mount Everest (8848 m (29029 ft)) in the Himalayas of Asia. The highest known mountain in the Solar System is Olympus Mons on the planet Mars at 21171 m (69459 ft). Contents 1 Definition 2 Characteristics 3 Types 4 Geology 4.1 Fold mountains 4.2 Fault-block mountain 4.3 Volcanoes 4.4 Mid-ocean ridges 5 See also 6 Notes 7 Further reading Definition The view of Jeff Davis Peak from the glacier-carved summit of Wheeler Peak Nevada. Because Boundary Peak Nevada is partially in California and is actually a sub-peak of Montgomery Peak the shorter Wheeler Peak can be considered the tallest mountain in Nevada.

There is no universally accepted definition of a mountain. Elevation volume relief steepness spacing and continuity have been used as criteria for defining a mountain.1 In the Oxford English Dictionary a mountain is defined as "a natural elevation of the earth surface rising more or less abruptly from the surrounding level and attaining an altitude which relatively to the adjacent elevation is impressive or notable."1

Whether a landform is called a mountain may depend on usage among the local people. The highest point in San Francisco California is called Mount Davidson notwithstanding its height of 300 m (980 ft) which makes it ten feet short of the minimum for a mountain by American designations.citation needed Similarly Mount Scott outside Lawton Oklahoma is only 251 m (823 ft) from its base to its highest point.

Definitions of "mountain" include:2 Height over base of at least 2500 m (8202 ft). Height over base of 1500 m (4921 ft).2500 m (8202 ft). with a slope greater than 2 degrees Height over base of 1000 m (3281 ft).1500 m (4921 ft). with a slope greater than 5 degrees Local (radius 7000 m (22966 ft). elevation greater than 300 m (984 ft). or 300 m (984 ft)1000 m (3281 ft). if local (radius 7000 m (22966 ft). elevation is greater than 300 m (984 ft).

By this definitionwhich mountains cover 64% of Asia 25% of Europe 22% of South America 17% of Australia and 3% of Africa. As a whole 24% of the Earth's land mass is mountainous and 10% of people live in mountainous regions.3 Most of the world's rivers are fed from mountain sources and more than half of humanity depends on mountains for water.45 Characteristics Mountain in Carbon County Utah

Tall mountains reach into the colder layers of the atmosphere. They are consequently subject to glaciation and erosion through frost action. Such processes produce the peak shape. Some of these mountains have glacial lakes created by melting glaciers; for example there are an estimated 3000 glacial lakes in Bhutan. Mountains can be eroded and weathered altering their characteristics over time. Mount Olympus in Greece

Tall mountains have different climatic conditions at the top than at the base and will thus have altitudinal zonation of ecosystems. At the highest elevations trees cannot grow and whatever life may be present will be of the alpine type resembling tundra.6 Just below the tree line one may find subalpine forests of needleleaf trees which can withstand cold dry conditions.7 In regions with dry climates the tendency of mountains to have higher precipitation as well as lower temperatures also provides for varying conditions which in turn lead to differing flora and fauna.68 Some plants and animals found in these zones tend to become isolated since the conditions above and below a particular zone will be inhospitable and thus constrain their movements or dispersal. On the other hand birds being capable of flight may take advantage of montane habitats and migrate into a region that would otherwise not provide appropriate habitat.9 These isolated ecological systems or microclimates are known as sky islands.10

The reason mountains are colder than lowlands has to do with how the sun heats the surface of the Earth. Practically all the heat at the surface of the Earth comes from the sun in the form of solar energy. The sun's radiation is absorbed by land and sea whence the heat is transferred into the air. Air is an insulator so conduction of heat from the ground to the atmosphere is negligible. Heat is mainly transferred into the atmosphere through convection and radiation. Warm air rises because of its buoyancy leading to convective circulation in the form of thermals within the lowest layer of the atmosphere the troposphere. When heat radiates from the surface of the earth it is released as long-wave radiation which does not travel through the air efficiently. This radiant heat is absorbed temporarily by gasses in the atmosphere such as carbon dioxide and water vapor. Thus the lower portion of the tropospheremore than 50% of all air lies below the altitude of the summit of Mt. Everestforms a blanket of air keeping the surface warm. This is the Greenhouse Effect. The higher one goes in altitude the less of this blanket there is to keep in the heat. Thus higher elevations such as mountains are colder than surrounding lowlands.11 Air temperature in the lowest layer of the atmosphere the troposphere decreases with gains in altitude. The rate at which the temperature drops with elevation called the environmental lapse rate is not constant (it can fluctuate throughout the day or seasonally and also regionally) but a normal lapse rate is 5.5C per 1000 m (3F per 3000 ft).1213 The temperature continues to drop up to a height of about 916 km where it does not decrease further. However this is higher than the highest mountaintop. Mountains are generally less preferable for human habitation than lowlands; the weather is often harsher and there is little level ground suitable for agriculture. At very high altitudes there is less oxygen in the air and less protection against solar radiation (UV). Acute mountain sickness (caused by hypoxiaa lack of oxygen in the blood) affects over half of lowlanders who spend more than a few hours above 3500 metres (11480 ft). Many mountains and mountain ranges throughout the world have been left in their natural state and are today primarily used for recreation while others are used for logging mining grazing or see little use. Some mountains offer spectacular views from their summits while others are densely wooded. Summit accessibility is affected by height steepness latitude terrain weather. Roads lifts or tramways affect accessibility. Hiking backpacking mountaineering rock climbing ice climbing downhill skiing and snowboarding are recreational activities enjoyed on mountains. Mountains that support heavy recreational use (especially downhill skiing) are often the locations of mountain resorts. Mountains are made up of earth and rock materials. The outermost layer of the Earth or the Earth's crust is composed of seven primary plates. When two plates move or collide each other vast land areas are uplifted resulting in the formation of mountains. Types This section does not cite any references or sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (October 2010) Classified by the geological processes that shape them there are five major types of mountains: Left to right: Mount Everest Lhotse and Ama Dablam in the Himalayas Mount Kilimanjaro 5895 metres (19341 ft) Tanzania Fold mountains Fold mountains are the most common type of mountains. They are formed due to collision of two plates causing folding of the Earth's crust. The fold that descends on both sides is called anticline; whereas the fold that ascends from a common low point (on both sides) is called syncline. Examples of fold mountains are the Himalayas of Asia and the Alps in Europe. Fault-Block mountains As the name suggests fault-block mountains or fault mountains are formed when blocks of rock materials slide along faults in the Earth's crust. There are two types of block mountains namely the lifted and tilted. Lifted mountains have two steep sides; whereas the tilted type has one steep side and a gentle sloping side. Examples of fault-block mountains are found in the Sierra Nevada mountain range of the western United States. Volcanic mountains Volcanic mountains are formed due to volcanic eruptions where magma piles up on the surface of the Earth. Examples of volcanoes include Mount Fuji in Japan and Mount Pinatubo in the Philippines. Dome mountains Dome mountains are formed when the hot magma rises from the mantle and uplifts the overlying sedimentary layer of the Earth's crust. In the process the magma is not erupted but it cools down and forms the core of the mountain. They are called dome mountains due to their appearance that resembles a dome shape. An example of a dome mountain is Navajo Mountain in the U.S. state of Utah. The Adirondack Mountains of New York are pseudo mountains. Plateau mountains Plateau mountains are pseudo mountains that are formed because of erosion. They usually occur near folded mountain ranges. An example of a plateau mountain is the Adirondack Mountains in the U.S. state of New York. Some mountains are formed as a result of several of the Earth's forces. Though the Rockies in North America is formed due to folding there are mountains in the same range that are formed by faulting and doming. In nature there is a continuous process of glaciation soil erosion and mechanical and chemical weathering which altogether play a major role in altering the shape and characteristics of mountains. Geology The Himalayan mountain range with Mount Everest Main articles: Orogeny and Mountain formation A mountain is usually produced by the movement of lithospheric plates either orogenic movement or epeirogenic movement. Compressional forces isostatic uplift and intrusion of igneous matter forces surface rock upward creating a landform higher than the surrounding features. The height of the feature makes it either a hill or if higher and steeper a mountain. The absolute heights of features termed mountains and hills vary greatly according to an area's terrain. The major mountains tend to occur in long linear arcs indicating tectonic plate boundaries and activity. Two types of mountain are formed in this way depending on how the rock reacts to the tectonic forces fold mountains or fault-block mountains. Other mountain building processes include volcanoes and sea floor spreading. Fold mountains Compressional forces in continental collisions may cause the compressed region to thicken and fold with material forced both upwards and downwards. Since the less dense continental crust "floats" (cf iceberg) on the denser mantle rocks beneath the weight of any crustal material forced upward to form hills plateaus or mountains must be balanced by the buoyancy force (see isostasy) of a much greater volume forced downward into the mantle. Thus the continental crust is normally much thicker under mountains ( sometimes called "mountain roots")14 compared to lower lying areas. However in many continental collisions (e.g. the Himalayas) part of one continent may simply override the other crumpling in the process with the overridden crust forming much of the support. Mountains may similarly be partly supported by oceanic crust subducted beneath the continental crust (e.g. the Andes as the Nazca plate flows beneath the South American Plate). Fault-block mountain Blue Ridge Mountains in Shenandoah National Park Virginia USA Block mountains are created when large areas are widely broken up by faults creating large vertical displacements. This occurrence is fairly common. The uplifted blocks are block mountains or horsts. The intervening dropped blocks are termed graben: these can be small or form extensive rift valley systems. This form of landscape can be seen in East Africa the Vosges the Basin and Range province of Western North America and the Rhine valley. These areas often occur when the regional stress is extensional and the crust is thinned. Rock that does not fault may fold either symmetrically or asymmetrically. The upfolds are anticlines and the downfolds are synclines: in asymmetric folding there may also be recumbent and overturned folds. The Jura Mountains are an example of folding. Over time erosion can bring about an inversion of relief: the soft upthrust rock is worn away so the anticlines are actually lower than the tougher more compressed rock of the synclines. Volcanoes Some isolated mountains are produced by volcanoes including many apparently small islands or seamounts that reach a great height above the ocean floor. Mid-ocean ridges The mid-ocean ridges formed during sea-floor spreading are often referred to as undersea mountain ranges due to their bathymetric prominence. See also Environment portal Ecology portal The Zugspitze the highest mountain in Germany List of mountains List of mountain types Category:Lists of mountains Mountain range List of mountain ranges List of highest mountains List of peaks by prominence Latin names of mountains List of ski areas and resorts Mountaineering Mountain building Notes a b Gerrard A. J. 1990. Mountain Environments Blyth S. Groombridge B. Lysenko I. Miles L. & Newton A. (2002). "Mountain Watch". UNEP World Conservation Monitoring Centre Cambridge UK. http://www.unep-wcmc.org/mountains/mountainwatch/pdfs/WholeReport.pdf. Retrieved 2009-02-17.  Panos (2002). "High Stakes". http://www.panos.org.uk/lid278. Retrieved 2009-02-17.  "International Year of Freshwater 2003". http://www.wateryear2003.org/en/ev.php-URLID3903&URLDODOTOPIC&URLSECTION201.html. Retrieved 2006-12-07.  "The Mountain Institute". http://www.mountain.org/mountains/whymtns.cfmslidepagewater. Retrieved 2006-12-07.  a b "Biotic Communities of the Colorado Plateau: C. Hart Merriam and the Life Zones Concept". http://cpluhna.nau.edu/Biota/merriam.htm. Retrieved 30 January 2010.  "Tree". Microsoft Encarta Reference Library 2003. Microsoft Corporation. 1993-2002. 60210-442-1635445-74407.  "Mountain Environments". United Nations Environment Programme World Conservation Monitoring Centre. http://www.unep-wcmc.org/mountains/mountainwatch/pdfs/mountainEnvironments.pdf. Retrieved 30 January 2010.  Taylor Richard Cachor (2005). A Birder's Guide to Southeastern Arizona. American Birding Association. pp. 24. ISBN 1-878788-22-1.  Tweit Susan J. (1992). The Great Southwest Nature Factbook. Alaska Northwest Books. pp. 209210. ISBN 0-88240-434-2.  Lutgens Frederick K.; Tarbuck Edward J. (1998). The Atmosphere: An Introduction to Meteorology. Prentice Hall. pp. 1517 3035 3840. ISBN 0-13-742974-6.  "Temperature". Microsoft Encarta Reference Library 2003. Microsoft Corporation. 1993-2002. 60210-442-1635445-74407.  "Atmosphere". Microsoft Encarta Reference Library 2003. Microsoft Corporation. 1993-2002. 60210-442-1635445-74407.  Press Frank and Siever Raymond Earth W. H. Freeman 4th ed. 1985 p. 413 ISBN 978-0716717430 Further reading Wikiquote has a collection of quotations related to: Mountains Wikimedia Commons has media related to: Mountains Wikisource has the text of the 1911 Encyclopdia Britannica article Mountain. Fraknoi A. Morrison D. & Wolff S. (2004). Voyages to the Planets. 3rd Ed. Belmont: Thomson Books/Cole. v d eEarth's landforms List of landforms Mountainous landforms Mountain  Mountain range  Plateaus  Hills  Valley Continental plain Plain  Tundra  Ice sheets River landform River  River Delta  Lakes  Meanders  Waterfalls  Rapids  River valley Fluvial landforms Alluvial fan  Beach  Canyons  Channel  Cave  Cliff  River Delta  Floodplain  Levee  Oasis  Swamp  Ponds Glacial landforms Arte  Cirques  Eskers  Fjords  Glacier  Tunnel valley Oceanic and coastal landforms Atoll  Bay  Channels  Coast  Continental shelf  Coral reef  Estuary  Lagoons  Mid-ocean ridge  Oceanic trench  Peninsula  Isthmus  Islands  Sea mount Volcanic landforms Volcanoes  Caldera  Crater Lake   Geyser  Hotspot  Oceanic ridges  Lava plain  Lava plateaus  Volcanic crater  Plugs  Wall rock  Lava dome  Submarine volcano (Guyot) Aeolian landforms Desert  Tundra  Dry lake  Dunes  Sandhill Artificial landforms Building  Bridge  Canals (man-made channels)  Dams  Dikes  Artificial Lakes  Polder  Artificial islands  Artificial reef  Tunnel  Quarry  Ditch  Road  Reclaimed land see also Geographical feature