A
mountain is a large
landformIn the earth sciences and geology sub-fields, a landform or physical feature comprises a geomorphological unit, and is largely defined by its surface form and location in the landscape, as part of the terrain, and as such, is typically an element of topography...
that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a
hillA hill is a landform that extends above the surrounding terrain, in a limited area. Hills often have a distinct summit, although in areas with scarp/dip topography a hill may refer to a particular section of scarp slope without a well-defined summit A hill is a landform that extends above the...
. The adjective
montane is used to describe mountainous areas and things associated with them. The study of mountains is Orology.
Exogeology deals with planetary mountains, which in that branch of science are usually called
montes (singular -
mons). The highest known mountain in the
Solar SystemThe Solar System consists of the Sun and those celestial objects bound to it by gravity, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago...
is
Olympus MonsOlympus Mons is the tallest known volcano and mountain in the Solar System and was formed during the Amazonian epoch. It is located on the planet Mars at approximately 18°N 133°W / 18, -133. It is three times as tall as Mount Everest...
on the planet
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
(elevation 21,171 m).
Definition
There is no universally-accepted definition of mountain. Elevation, volume, relief, steepness, spacing and continuity has been used as criteria for defining a mountain. In the
Oxford English DictionaryThe Oxford English Dictionary , published by the Oxford University Press , is a comprehensive dictionary of the English language...
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."
In the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
, the following points of measurement have been used and taught in geography classes:
- Flat to 500 feet, base to highest point - Rolling Plain
- Highest point 501 to 999 feet above base - Hill
- Highest point 1000 feet or more above base - Mountain
Whether a landform is called a mountain may depend on usage among the local people. The highest point in
San FranciscoSan Francisco is the fourth most populous city in California and the 12th most populous city in the United States, with a 2008 estimated population of 808,976. It is the eighth most densely populated city in the U.S. and is the financial, cultural, and transportation center of the larger San...
,
CaliforniaCalifornia is the most populous state in the United States, and the third largest by area. California is the second most populous sub-national entity in the Americas, behind only São Paulo, Brazil...
, is called Mount Davidson, notwithstanding its height of 990 feet, which makes it ten feet short of the minimum for a mountain in American appellation.
Other definitions of "mountain" include:
- Height over base of at least 2,500m
- Height over base of 1500-2500m with a slope greater than 2 degrees
- Height over base of 1000-1500m with a slope greater than 5 degrees
- Local (radius 7 km) elevation greater than 300m, or 300-1000m if local (radius 7 km) elevation is greater than 300m
By this definition, mountains cover 64% of
AsiaAsia is the world's largest and most populous continent, located in the eastern and northern hemispheres. It covers 8.6% of the earth's total surface area and with approximately 4 billion people, it hosts 60% of the world's current human population.Asia is traditionally defined as part of the...
, 25% of
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
, 22% of
South AmericaSouth America is the southern continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere...
, 17% of
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...
, and 3% of
AfricaAfrica is the world's second-largest and second most-populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area. With a billion people in 61 territories, it accounts for about 14.8% of the...
. As a whole, 24% of the Earth's land mass is mountainous and 10% of people live in mountainous regions. Most of the world's rivers are fed from mountain sources, and more than half of humanity depends on mountains for water.
Characteristics
High mountains, as well as those located close to the Earth's poles, reach into the colder layers of the atmosphere. They are consequently subject to glaciation, and
erosionErosion is a gravity driven process that moves solids in the natural environment or their source and deposits them elsewhere...
through frost action. Such processes produce the
peakA pyramidal peak, or sometimes in its most extreme form called a glacial horn, is a mountaintop that has been modified by the action of ice during glaciation and frost weathering...
shape. Some of these mountains have
glacial lakeA glacial lake is a lake with origins in a melted glacier. Roughly, 10,000 years ago glaciers began to retreat, near the end of the Ice Age....
s, created by melting glaciers; for example, there are an estimated 3,000 glacial lakes in
BhutanThe Kingdom of Bhutan is a landlocked nation in South Asia, located at the eastern end of the Himalaya Mountains and is bordered to the south, east and west by the Republic of India and to the north by People's Republic of China. Bhutan is separated from the nearby state of Nepal to the west by...
. Mountains can be
erodedErosion is a gravity driven process that moves solids in the natural environment or their source and deposits them elsewhere...
and
weatheredWeathering is the decomposition of Earth's rocks, soils and minerals through direct contact with the planet's atmosphere. Weathering occurs in situ, or "with no movement", and thus should not be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice,...
, altering their characteristics over time.
Tall mountains have different climatic conditions at the top than at the base, and will thus have different
life zoneThe Life Zone concept was developed by C. Hart Merriam in 1889 as a means of describing areas with similar plant and animal communities. Merriam observed that the changes in these communities with an increase in latitude at a constant elevation are similar to the changes seen with an increase in...
s at different altitudes. The flora and fauna found in these zones tend to become isolated since the conditions above and below a particular zone will be inhospitable to those organisms. These isolated ecological systems are known as
sky islandSky islands are mountains in ranges isolated by valleys in which other ecosystems are located. As a result, the mountain ecosystems are isolated from each other, and species can develop in parallel, as on island groups such as the Galápagos Islands....
s and/or microclimates. Alpine forests are forests on mountain sides.
Mountains are colder than lower ground, because the Sun heats Earth from the ground up. The Sun's radiation travels through the atmosphere to the ground, where Earth absorbs the heat. Air closest to the Earth's surface is, in general, warmest (see
lapse rateThe lapse rate is defined as the rate of decrease with height for an atmospheric variable. The variable involved is temperature unless specified otherwise. The terminology arises from the word lapse in the sense of a decrease or decline; thus, the lapse rate is the rate of decrease with height and...
for details). Air temperature normally drops 1 to 2 degrees Celsius (1.8 to 3.6 degrees Fahrenheit) for each 300 meters (1000 ft) of altitude.
Mountains are generally less preferable for
humanHumans are bipedal primates belonging to the species Homo sapiens in Hominidae, the great ape family. They are the only surviving member of the genus Homo. Humans have a highly developed brain, capable of abstract reasoning, language, introspection, and problem solving...
habitation than lowlands; the weather is often harsher, and there is little level ground suitable for
agricultureAgriculture is the production of food and goods through farming and forestry. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants creating food surpluses that enabled the development of more densely populated and...
. At very high altitudes, there is less
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
in the air and less protection against solar radiation (
UVUltraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
). Acute mountain sickness (caused by
hypoxiaHypoxia is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
- a lack of oxygen in the blood) affects over half of lowlanders who spend more than a few hours above 3,500 meters (11,483 ft).
Mountains and mountain ranges throughout the world have been left in their natural state, and are today primarily used for
recreationRecreation or fun is the expenditure of time in a manner designed for therapeutic refreshment of one's body or mind. While leisure is more likely a form of entertainment or sleep, recreation is active for the participant but in a refreshing and diverting manner...
, while others are used for
loggingLogging is the process in which certain trees are cut down for forest management and timber.In forestry the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard. In common usage...
,
miningMining is the extraction of valuable minerals or other geological materials from the earth, usually from an ore body, vein or seam. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt and potash...
,
grazingGrazing generally describes a type of predation in which an herbivore feeds on plants , and also on other multicellular autotrophs...
, 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.
RoadA road is an identifiable route, way or path between places.
s,
liftsThe term ski lift can refer to many different types of uphill transport, in three main classes:-Lift systems and networks:The network lifts at a ski resort can be arranged in several patterns depending on the size and topography of the area. Several lifts may be arranged radially outward from a...
, or
tramwaysAn aerial tramway or cable car is a type of aerial lift in which a cabin or other conveyance is suspended from a fixed cable and is pulled by another cable....
affect accessibility.
HikingHiking is an outdoor activity which consists of walking in natural environments, often on hiking trails. It is such a popular activity that there are numerous hiking organizations worldwide. The health benefits of different types of hiking have been confirmed in studies...
,
backpackingBackpacking combines hiking and camping in a single trip. A backpacker hikes into the backcountry to spend one or more nights there, and carries supplies and equipment to satisfy sleeping and eating needs.-Definition:A backpacker packs all of his or her gear into a backpack...
,
mountaineeringMountaineering is the sport, hobby or profession of walking, hiking, backpacking and climbing mountains. In Europe it is also referred to as alpinism, while in the Americas the term refers to a particular style of mountain climbing, that involves a mixture of ice climbing, rock climbing, mixed...
,
rock climbingRock climbing is a sport in which participants climb up or across natural rock formations or man-made rock walls. The goal is to reach the summit of a formation or the endpoint of a pre-defined route...
,
ice climbingIce climbing, as the term indicates, is the activity of ascending inclined ice formations. Usually, ice climbing refers to roped and protected climbing of features such as icefalls, frozen waterfalls, and cliffs and rock slabs covered with ice refrozen from flows of water. For the purposes of...
, downhill skiing, and
snowboardingSnowboarding is a sport that involves descending a slope that is either partially or fully covered with snow on a snowboard attached to a rider's feet using a special boot set into a mounted binding. The development of snowboarding was inspired by skateboarding, surfing and skiing...
are recreational activities enjoyed on mountains. Mountains that support heavy recreational use (especially downhill skiing) are often the locations of
mountain resortThe Mountain Resort in Chengde or Ligong situated in the city of Chengde in Hebei Province, China, is the world's largest existing imperial garden.Built between 1703 and 1792, the Mountain Resort took 89...
s.
Types of mountains
Mountains can be characterized in several ways. Some mountains are volcanoes and can be characterized by the type of lava. Other mountains are shaped by
glacial processesA glacier is a perennial mass of ice which moves over land. A glacier forms in locations where the mass accumulation of snow and ice exceeds ablation over many years...
and can be characterized by their glaciated features. Still others are typified by the faulting and
foldingThe term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of plastic deformation. Synsedimentary folds are those due to slumping of sedimentary material before it is lithified. Folds in rocks vary in size...
of the Earth's crust, or by the collision of continental plates via
plate tectonicsPlate tectonics is a theory which describes the large scale motions of Earth's lithosphere...
(the Himalayas, for instance). Shape and placement within the overall landscape also define mountains and mountainous structures (such as
butteA butte is an isolated hill with steep, often vertical sides and a small, relatively flat top; smaller than mesas, plateaus, and tables. In some regions the word is simply used for any hill...
and
monadnockA monadnock or inselberg is an isolated rock hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain. The term "monadnock" is usually used in the United States, whereas "inselberg" is the more common international term...
). Finally, mountains can be characterized by the type of
rockIn geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
that make up their composition.
Geology
Image:Himalaya_annotated.jpg|thumb|right|The Himalayan mountain range with Mount Everest.
rect 58 14 160 49 Chomo LonzoChomo-Lonzo is a mountain in Tibet, 5 km northeast of Makalu in the Mahalungur or Khumbu Himalayas.Chomo-Lonzo has three distinct summits...
rect 200 28 335 52 MakaluMakalu is the fifth highest mountain in the world and is located east of Mount Everest, on the border between Nepal and China. One of the eight-thousanders, Makalu is an isolated peak whose shape is a four-sided pyramid.Makalu has two notable subsidiary peaks...
rect 378 24 566 45 Mount EverestMount Everest – also called Sagarmāthā , Chomolungma or Qomolangma or Zhumulangma – is the highest mountain on Earth, and the highest point on the Earth's crust, as measured by the height above sea level of its summit,...
rect 188 581 920 656 Tibetan PlateauThe Tibetan Plateau , also known as the Tibel-Qingai Plateau or Qinghai-Tibetan Plateau is a vast, elevated plateau in Central Asia covering most of the Tibet Autonomous Region and Qinghai Province in China and Ladakh in Kashmir, India...
rect 250 406 340 427 Rong River
rect 333 149 409 186 ChangtseChangtse is a mountain situated between the Main Rongbuk and East Rongbuk Glaciers in Tibet immediately north of Mount Everest. It is connected to Mount Everest via the North Col....
rect 550 284 677 303 Rongbuk GlacierImage:Himalaya_annotated.jpg|thumb|250px|right|Rongbuk Glacier and Mount Everest as seen from the International Space Station.rect 58 14 160 49 Chomo Lonzorect 200 28 335 52 Makalurect 378 24 566 45 Mount Everestrect 188 581 920 656 Tibetan Plateau...
rect 478 196 570 218 North FaceMount Everest – also called Sagarmāthā , Chomolungma or Qomolangma or Zhumulangma – is the highest mountain on Earth, and the highest point on the Earth's crust, as measured by the height above sea level of its summit,...
rect 237 231 346 267 East Rongbuk Glacier
rect 314 290 536 309 North Col north ridge routeMount Everest – also called Sagarmāthā , Chomolungma or Qomolangma or Zhumulangma – is the highest mountain on Earth, and the highest point on the Earth's crust, as measured by the height above sea level of its summit,...
rect 531 79 663 105 LhotseLhotse is the fourth highest mountain on Earth and is connected to Everest via the South Col...
rect 582 112 711 130 NuptseNuptse is a mountain in the Khumbu region of the Mahalangur Himal, in the Nepalese Himalaya. It lies two kilometres WSW of Mount Everest. Nuptse is Tibetan for "west peak", as it is the western segment of the Lhotse-Nuptse massif....
rect 603 232 733 254 South Col routeThe South Col usually refers to the southern col between Mount Everest and Lhotse, the first and fourth highest mountains in the world. When climbers attempt to climb Everest from the southeast ridge in Nepal, their final camp is situated on the South Col...
rect 716 165 839 206 Gyachung KangGyachung Kang is a mountain in the Mahalangur Himal, a subrange of the Himalaya, and is the highest peak between Cho Oyu and Mount Everest . It lies on the border between Nepal and Tibet...
rect 882 147 967 183 Cho OyuCho Oyu is the sixth highest mountain in the world. Cho Oyu lies in the Himalayas and is 20 km west of Mount Everest, at the border between China and Nepal...
rect 1 1 999 661 
desc bottom-left
A mountain is usually produced by the movement of lithospheric plates, either
orogenic movementOrogeny refers to natural mountain building, and may be studied as a tectonic structural event, as a geographical event, and a chronological event...
or
epeirogenic movementEpeirogenic or continent forming movements, act along the radius of the earth. They are also called radial movements. Their direction maybe towards or away from the centre of the earth...
. The compressional forces, isostatic uplift and intrusion of
igneous matterIgneous rock is one of the three main rock types . Igneous rock is formed by magma being cooled and becoming solid. They may form with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks...
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
terrainTerrain, or relief, is the third or vertical dimension of land surface. When relief is described underwater, the term bathymetry is used...
. The major mountains tend to occur in long linear arcs, indicating tectonic plate boundaries and activity. Two types of mountain are formed depending on how the rock reacts to the tectonic forces – block mountains or fold mountains.
Compressional forces in continental collisions may cause the compressed region to thicken, so the upper surface is forced upward. In order to balance the weight of the earth surface, much of the compressed rock is forced
downward, producing deep "mountain roots" [see the Book of "Earth", Press and Siever page.413]. Mountains therefore form downward as well as upward (see
isostasyIsostasy is a term used in geology to refer to the state of gravitational equilibrium between the earth's lithosphere and asthenosphere such that the tectonic plates "float" at an elevation which depends on their thickness and density. This concept is invoked to explain how different topographic...
). However, in some continental collisions part of one continent may simply
override part of the others, crumpling in the process.
Some isolated mountains were produced by
volcano3. Conduit
4. Base
5. Sill
6. Dike
7. Layers of ash emitted by the volcano
8. Flank| 9. Layers of lava emitted by the volcano
10. Throat
11. Parasitic cone
12. Lava flow
13. Vent
14. Crater
15...
es, including many apparently small
islandAn island or isle is any piece of land that is surrounded by water. Very small islands such as emergent land features on atolls are called islets. A key or cay is another name for a small island or islet. An island in a river or lake may be called an eyot, .There are two main types of islands:...
s that reach a great height above the
oceanAn ocean is a large body of saline water, and a principal component of the hydrosphere. Approximately 75% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
floor.
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
horstsIn physical geography and geology, a horst is the raised fault block bounded by normal faults or graben. A horst is formed from extension of the Earth's crust...
. The intervening dropped blocks are termed
grabenA graben is a depressed block of land bordered by parallel faults. Graben is German for ditch.A graben is the result of a block of land being downthrown producing a valley with a distinct scarp on each side. Grabens often occur side-by-side with horsts. Horst and graben structures are indicative of...
: these can be small or form extensive rift valley systems. This form of
landscapeLandscape comprises the visible features of an area of land, including physical elements such as landforms, living elements of flora and fauna, abstract elements like lighting and weather conditions, and human elements like human activity and the built environment.-Etymology:The word landscape...
can be seen in
East AfricaEast Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
, the
VosgesThis article is about the department of France named Vosges. For the mountain range, see Vosges Mountains.Vosges is a French department, named after the local mountain range. It contains the hometown of Joan of Arc, Domrémy.-History:...
, the
Basin and RangeThe Basin and Range Province is a large geologic province which includes parts of the southwestern United States and northwestern Mexico, typified by basin and range topography.-Geography:...
province of Western
North AmericaNorth America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the 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 west by the North Pacific...
and the
RhineThe Rhine is one of the longest and most important rivers in Europe, at , with an average discharge of more than ....
valley. These areas often occur when the regional stress is extensional and the
crustIn geology, a crust is the outermost solid shell of a rocky planet or moon, which is chemically distinct from the underlying mantle. The crusts of Earth, our Moon, Mercury, Venus, Mars, Io, and other planetary bodies have been generated largely by igneous processes, and these crusts are richer in...
is thinned.
The
mid-ocean ridgeA mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, typically having a valley known as a rift running along its spine, formed by plate tectonics. This type of oceanic ridge is characteristic of what is known as an oceanic spreading center, which is responsible for seafloor...
s are often referred to as undersea mountain ranges due to their bathymetric prominence.
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.
See also
:Category:Lists of mountains
- Mountain range
A mountain range is a chain of mountains bordered by highlands or separated from other mountains by passes or valleys. Individual mountains within the same mountain range do not necessarily have the same geology, though they often do; they may be a mix of different orogeny, for example volcanoes,...
- List of mountain ranges
- List of highest mountains
- List of peaks by prominence
- Latin names of mountains
Users of Neo-Latin have taken the Latin language to places the Romans never went; hence a need arose to make Latin names of mountains that did not exist when Latin was a living language.-Strategies for constructing Latin names:-List of names:...
- List of ski areas and resorts
- Mountaineering
Mountaineering is the sport, hobby or profession of walking, hiking, backpacking and climbing mountains. In Europe it is also referred to as alpinism, while in the Americas the term refers to a particular style of mountain climbing, that involves a mixture of ice climbing, rock climbing, mixed...
Further reading
- Fraknoi, A., Morrison, D., & Wolff, S. (2004). Voyages to the Planets. 3rd Ed. Belmont: Thomson Books/Cole.
External links