A mountain is an elevated portion of the
Earth's crust is Earth's thin outer shell of rock, referring to less than 1% of Earth's radius and volume. It is the top component of the lithosphere, a division of Earth's layers that includes the crust and the upper part of the mantle. The ...
, generally with steep sides that show significant exposed bedrock
. Although definitions vary, a mountain may differ from a plateau
in having a limited
A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. The topographic terms acme, apex, peak (mountain peak), and zenith are synonymous.
The term (mountain top) is generally used only for a ...
area, and is usually higher than a
A hill is a landform that extends above the surrounding terrain. It often has a distinct summit.
The distinction between a hill and a mountain is unclear and largely subjective, but a hill is universally considered to be not as ...
, typically rising at least 300 metres (1,000 feet) above the surrounding land. A few mountains are isolated summits
, but most occur in mountain range
Mountains are formed
through tectonic forces
, or volcanism
which act on time scales of up to tens of millions of years.
Once mountain building ceases, mountains are slowly leveled through the action of weathering
, through slumping
and other forms of
Mass wasting, also known as mass movement, is a general term for the movement of rock or soil down slopes under the force of gravity. It differs from other processes of erosion in that the debris transported by mass wasting is not entrained i ...
, as well as through erosion by river
s and glacier
High elevations on mountains produce colder climates
than at sea level
at similar latitude. These colder climates strongly affect the
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
of mountains: different elevations have different plants and animals. Because of the less hospitable terrain and climate, mountains tend to be used less for agriculture and more for resource extraction, such as mining
, along with recreation, such as mountain climbing
The highest mountain on Earth is Mount Everest
in the Himalayas
, whose summit is above mean sea level. The highest known mountain
on any planet in the Solar System is Olympus Mons
on Mars at .
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.
[ 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."] [
Whether a landform is called a mountain may depend on local usage. Mount Scott outside ] Lawton, Oklahoma
Lawton is a city in and the county seat of Comanche County, in the U.S. state of Oklahoma. Located in southwestern Oklahoma, approximately southwest of Oklahoma City, it is the principal city of the Lawton, Oklahoma, metropolitan statistical a ..., US, is only from its base to its highest point. John Whittow's ''Dictionary of Physical Geography'' states "Some authorities regard eminences above as mountains, those below being referred to as hills."
In the United Kingdom and the Republic of Ireland, a mountain is usually defined as any summit at least high, which accords with the official UK government's definition that a mountain, for the purposes of access, is a summit of or higher. In addition, some definitions also include a topographical prominence
In topography, prominence (also referred to as autonomous height, relative height, and shoulder drop in US English, and drop or relative height in British English) measures the height of a mountain or hill's summit relative to the lowest conto ... requirement, such as that the mountain rises above the surrounding terrain. At one time the US Board on Geographic Names defined a mountain as being or taller, but has abandoned the definition since the 1970s. Any similar landform lower than this height was considered a hill. However, today, the US Geological Survey concludes that these terms do not have technical definitions in the US.
The UN Environmental Programme's definition of "mountainous environment" includes any of the following: [
* Class 1: Elevation greater than .
* Class 2: Elevation between and .
* Class 3: Elevation between and .
* Class 4: Elevation between and , with a slope greater than 2 degrees.
* Class 5: Elevation between and , with a slope greater than 5 degrees and/or elevation range within .
* Class 6: Elevation between and , with a elevation range within .
* Class 7: Isolated inner basins and plateaus less than in area that are completely surrounded by Class 1 to 6 mountains, but do not themselves meet criteria for Class 1 to 6 mountains.
Using these definitions, mountains cover 33% of Eurasia, 19% of South America, 24% of North America, and 14% of Africa.] [ As a whole, 24% of the Earth's land mass is mountainous.]
There are three main types of mountains:
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plates ar ..., fold, and block. All three types are formed from plate tectonics: when portions of the Earth's crust move, crumple, and dive. 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. Major mountains tend to occur in long linear arcs, indicating tectonic plate boundaries and activity.
Volcanoes are formed when a plate is pushed below another plate, or at a mid-ocean ridge or hotspot.
At a depth of around , melting occurs in rock above the slab (due to the addition of water), and forms magma that reaches the surface. When the magma reaches the surface, it often builds a volcanic mountain, such as a shield volcano
A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more v ... or a stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and p .... [ Examples of volcanoes include Mount Fuji in Japan and ] Mount Pinatubo
Mount Pinatubo is an active stratovolcano in the Zambales Mountains, located on the tripoint boundary of the Philippine provinces of Zambales, Tarlac and Pampanga, all in Central Luzon on the northern island of Luzon. Its eruptive histor ... in the Philippines. The magma does not have to reach the surface in order to create a mountain: magma that solidifies below ground can still form dome mountains, such as Navajo Mountain in the US.
Fold mountains occur when two plates collide: shortening occurs along thrust faults and the crust is overthickened.
Since the less dense continental crust
Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called ''sial'' be ... "floats" 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 of a much greater volume forced downward into the mantle. Thus the continental crust is normally much thicker under mountains, compared to lower lying areas. Rock can fold either symmetrically or asymmetrically. The upfolds are anticline
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...s and the downfolds are syncline
In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimposed ...s: in asymmetric folding there may also be recumbent and overturned folds. The Balkan Mountains and the Jura Mountains are examples of fold mountains.
Block mountains are caused by faults in the crust: a plane where rocks have moved past each other. When rocks on one side of a fault rise relative to the other, it can form a mountain.
The uplifted blocks are block mountains or horsts. The intervening dropped blocks are termed graben
In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults.
''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic contex ...: these can be small or form extensive rift valley
A rift valley is a linear shaped lowland between several highlands or mountain ranges created by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear ... systems. This form of landscape can be seen in East Africa, the Vosges
The Vosges ( , ; german: Vogesen ; Franconian and gsw, Vogese) are a range of low mountains in Eastern France, near its border with Germany. Together with the Palatine Forest to the north on the German side of the border, they form a single ... and Rhine valley, and the Basin and Range Province of Western North America. These areas often occur when the regional stress is extensional and the crust is thinned.
During and following uplift, mountains are subjected to the agents of erosion (water, wind, ice, and gravity) which gradually wear the uplifted area down. Erosion causes the surface of mountains to be younger than the rocks that form the mountains themselves.
[ Glacial processes produce characteristic landforms, such as ] pyramidal peak
A pyramidal peak, sometimes called a glacial horn in extreme cases, is an angular, sharply pointed mountain peak which results from the cirque erosion due to multiple glaciers diverging from a central point. Pyramidal peaks are often examples o ...s, knife-edge arête
An arête ( ) is a narrow ridge of rock which separates two valleys. It is typically formed when two glaciers erode parallel U-shaped valleys. Arêtes can also form when two glacial cirques erode headwards towards one another, although frequ ...s, and bowl-shaped cirque
A (; from the Latin word ') is an amphitheatre-like valley formed by glacial erosion. Alternative names for this landform are corrie (from Scottish Gaelic , meaning a pot or cauldron) and (; ). A cirque may also be a similarly shaped landfo ...s that can contain lakes. Plateau mountains, such as the Catskills
The Catskill Mountains, also known as the Catskills, are a physiographic province of the larger Appalachian Mountains, located in southeastern New York. As a cultural and geographic region, the Catskills are generally defined as those areas c ..., are formed from the erosion of an uplifted plateau.
Climate in the mountains becomes colder at high elevations, due to an interaction between radiation and convection. Sunlight in the visible spectrum hits the ground and heats it. The ground then heats the air at the surface. If radiation were the only way to transfer heat from the ground to space, the
The greenhouse effect is a process that occurs when energy from a planet's host star goes through the planet's atmosphere and heats the planet's surface, but greenhouse gases in the atmosphere prevent some of the heat from returning directly ... of gases in the atmosphere would keep the ground at roughly , and the temperature would decay exponentially with height.
However, when air is hot, it tends to expand, which lowers its density. Thus, hot air tends to rise and transfer heat upward. This is the process of convection. Convection comes to equilibrium when a parcel of air at a given altitude has the same density as its surroundings. Air is a poor conductor of heat, so a parcel of air will rise and fall without exchanging heat. This is known as an adiabatic process
In thermodynamics, an adiabatic process (Greek: ''adiábatos'', "impassable") is a type of thermodynamic process that occurs without transferring heat or mass between the thermodynamic system and its environment. Unlike an isothermal process, ..., which has a characteristic pressure-temperature dependence. As the pressure gets lower, the temperature decreases. The rate of decrease of temperature with elevation is known as the adiabatic lapse rate, which is approximately 9.8 °C per kilometre (or per 1000 feet) of altitude. [
The presence of water in the atmosphere complicates the process of convection. Water vapor contains latent ] heat of vaporization
The enthalpy of vaporization (symbol ), also known as the (latent) heat of vaporization or heat of evaporation, is the amount of energy (enthalpy) that must be added to a liquid substance to transform a quantity of that substance into a gas. T .... As air rises and cools, it eventually becomes saturated and cannot hold its quantity of water vapor. The water vapor condenses (forming cloud
In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may com ...s), and releases heat, which changes the lapse rate from the dry adiabatic lapse rate
The lapse rate is the rate at which an atmospheric variable, normally temperature in Earth's atmosphere, falls with altitude. ''Lapse rate'' arises from the word ''lapse'', in the sense of a gradual fall. In dry air, the adiabatic lapse rate is ... to the moist adiabatic lapse rate
The lapse rate is the rate at which an atmospheric variable, normally temperature in Earth's atmosphere, falls with altitude. ''Lapse rate'' arises from the word ''lapse'', in the sense of a gradual fall. In dry air, the adiabatic lapse rate is ... (5.5 °C per kilometre or per 1000 feet)
The actual lapse rate can vary by altitude and by location.
Therefore, moving up on a mountain is roughly equivalent to moving 80 kilometres (45 miles or 0.75° of latitude) towards the nearest pole. [ This relationship is only approximate, however, since local factors such as proximity to oceans (such as the Arctic Ocean) can drastically modify the climate. As the altitude increases, the main form of precipitation becomes snow and the winds increase.] [
The effect of the climate on the ecology at an elevation can be largely captured through a combination of amount of precipitation, and the biotemperature, as described by Leslie Holdridge in 1947. Biotemperature is the mean temperature; all temperatures below are considered to be 0 °C. When the temperature is below 0 °C, plants are dormant, so the exact temperature is unimportant. The peaks of mountains with permanent snow can have a biotemperature below .]
Mountain environments are particularly sensitive to anthropogenic climate change and are currently undergoing alterations unprecedented in last 10,000 years. In recent decades mountain ice caps and glaciers have experienced accelerating ice loss. The melting of the glaciers, permafrost and snow has caused underlying surfaces to become increasingly unstable. Landslip hazards have increased in both number and magnitude due to climate change.
Alpine ecosystems can also thus be particularly climatically sensitive. Many mid-latitude mountains act as cold climate refugia, with the ecosystems occupying small environmental niches. As well as the direct influence that the change in climate can have on an ecosystem, there is also the indirect one on the soils from changes in stability and soil development.
Patterns of river discharge are also significantly affected by climate change, which in turn has significant impacts on communities that rely on water fed from alpine sources. Nearly half of mountain areas provide essential or supportive water resources for mainly urban populations, in particular during the dry season and in semiarid areas such as in central Asia.
The colder climate on mountains affects the plants and animals residing on mountains. A particular set of plants and animals tend to be adapted to a relatively narrow range of climate. Thus, ecosystems tend to lie along elevation bands of roughly constant climate. This is called
Altitudinal zonation (or elevational zonation) in mountainous regions describes the natural layering of ecosystems that occurs at distinct elevations due to varying environmental conditions. Temperature, humidity, soil composition, and solar rad ....
In regions with dry climates, the tendency of mountains to have higher precipitation as well as lower temperatures also provides for varying conditions, which enhances zonation.
Some plants and animals found in altitudinal zones tend to become isolated since the conditions above and below a particular zone will be inhospitable and thus constrain their movements or dispersal. These isolated ecological systems are known as sky island
Sky islands are isolated mountains surrounded by radically different lowland environments. The term originally referred to those found on the Mexican Plateau, and has extended to similarly isolated high-elevation forests. The isolation has s ...s.
Altitudinal zones tend to follow a typical pattern. At the highest elevations, trees cannot grow, and whatever life may be present will be of the alpine type, resembling tundra. Just below the tree line, one may find subalpine
Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial ... forests of needleleaf trees, which can withstand cold, dry conditions. Below that, montane forest
Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial ...s grow. In the temperate portions of the earth, those forests tend to be needleleaf trees, while in the tropics, they can be broadleaf trees growing in a rain forest
Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainforest, ....
Mountains and humans
The highest known permanently tolerable altitude is at .
At very high altitudes, the decreasing atmospheric pressure means that less oxygen is available for breathing, and there is less protection against solar radiation ( UV). [ Above elevation, there is not enough oxygen to support human life. This is sometimes referred to as the "] death zone
In mountaineering, the death zone refers to altitudes above a certain point where the pressure of oxygen is insufficient to sustain human life for an extended time span. This point is generally tagged as , less than 356 millibars of atmospheric ...". The summits of Mount Everest and K2 are in the death zone.
Mountain societies and economies
Mountains are generally less preferable for
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture ... habitation than lowlands, because of harsh weather and little level ground suitable for agriculture. While 7% of the land area of Earth is above , [ only 140 million people live above that altitude and only 20-30 million people above elevation. About half of mountain dwellers live in the Andes, Central Asia, and Africa.] [
With limited access to infrastructure, only a handful of human communities exist above of elevation. Many are small and have heavily specialized economies, often relying on industries such as agriculture, mining, and tourism. An example of such a specialized town is La Rinconada, Peru, a gold-mining town and the highest elevation human habitation at . A counterexample is El Alto, Bolivia, at , which has a highly diverse service and manufacturing economy and a population of nearly 1 million.
Traditional mountain societies rely on agriculture, with higher risk of crop failure than at lower elevations. Minerals often occur in mountains, with mining being an important component of the economics of some montane societies. More recently, tourism supports mountain communities, with some intensive development around attractions such as national parks or ski resorts.] [ About 80% of ] mountain people
Hill people, also referred to as mountain people, is a general term for people who live in the hills and mountains.
This includes all rugged land above and all land (including plateaus) above elevation.
The climate is generally harsh, with s ... live below the poverty line. [
Most of the world's rivers are fed from mountain sources, with snow acting as a storage mechanism for downstream users.] [ More than half of humanity depends on mountains for water.
In geopolitics mountains are often seen as preferable " natural boundaries" between polities.
Mountain climbing, or alpinism is the sport, hobby or
A profession is a field of work that has been successfully ''professionalized''. It can be defined as a disciplined group of individuals, '' professionals'', who adhere to ethical standards and who hold themselves out as, and are accepted by ... of hiking, skiing, and climbing mountains. While mountaineering began as attempts to reach the highest point of unclimbed big mountains it has branched into specializations that address different aspects of the mountain and consists of three areas: rock-craft, snow-craft and skiing, depending on whether the route chosen is over rock, snow or ice
Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opa .... All require experience, athletic ability, and technical knowledge of the terrain to maintain safety.
Mountains as sacred places
Mountains often play a significant role in religion. There are for example a number of sacred mountains within
Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders ... such as Mount Olympus
Mount Olympus (; el, Όλυμπος, Ólympos, also , ) is the highest mountain in Greece. It is part of the Olympus massif near the Thermaic Gulf of the Aegean Sea, located in the Olympus Range on the border between Thessaly and Macedonia, b ... which was held to be the home of the gods. In Japanese culture, the 3,776.24 m (12,389 ft) volcano of Mount Fuji is also held to be sacred with tens of thousands of Japanese ascending it each year. Mount Kailash
Mount Kailash (also Kailasa; ''Kangrinboqê'' or ''Gang Rinpoche''; Tibetan: གངས་རིན་པོ་ཆེ; ; sa, कैलास, ), is a mountain in the Ngari Prefecture, Tibet Autonomous Region of China. It has an altitude of ..., in the Tibet Autonomous Region of China, is considered to be sacred in four religions: Hinduism
Hinduism () is an Indian religion or '' dharma'', a religious and universal order or way of life by which followers abide. As a religion, it is the world's third-largest, with over 1.2–1.35 billion followers, or 15–16% of the global po ..., Bon, Buddhism, and Jainism. In Ireland, pilgrimages are made up the Mount Brandon by Irish Catholic
Irish Catholics are an ethnoreligious group native to Ireland whose members are both Catholic and Irish. They have a large diaspora, which includes over 36 million American citizens and over 14 million British citizens (a quarter of the Britis ...s. The Himalayan peak of Nanda Devi is associated with the Hindu goddesses Nanda and Sunanda; it has been off-limits to climbers since 1983. Mount Ararat
Mount Ararat or , ''Ararat''; or is a snow-capped and dormant compound volcano in the extreme east of Turkey. It consists of two major volcanic cones: Greater Ararat and Little Ararat. Greater Ararat is the highest peak in Turkey and th ... is a sacred mountain, as it is believed to be the landing place of Noah's Ark
Noah's Ark ( he, תיבת נח; Biblical Hebrew: ''Tevat Noaḥ'')The word "ark" in modern English comes from Old English ''aerca'', meaning a chest or box. (See Cresswell 2010, p.22) The Hebrew word for the vessel, ''teva'', occurs twice in t .... In Europe and especially in the Alps, summit crosses are often erected on the tops of prominent mountains.
Heights of mountains are typically measured
above sea level
Height above mean sea level is a measure of the vertical distance (height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as '' orthometric heights''.
The .... Using this metric, Mount Everest is the highest mountain on Earth, at . There are at least 100 mountains with heights of over above sea level
Height above mean sea level is a measure of the vertical distance (height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as '' orthometric heights''.
The ..., all of which are located in central and southern Asia. The highest mountains above sea level are generally not the highest above the surrounding terrain. There is no precise definition of surrounding base, but Denali
Denali (; also known as Mount McKinley, its former official name) is the highest mountain peak in North America, with a summit elevation of above sea level. With a topographic prominence of and a topographic isolation of , Denali is the th ..., Mount Kilimanjaro and Nanga Parbat
Nanga Parbat ( ur, ) (; ), known locally as Diamer () which means “king of the mountains”, is the ninth-highest mountain on Earth, its summit at above sea level. Lying immediately southeast of the northernmost bend of the Indus River in ... are possible candidates for the tallest mountain on land by this measure. The bases of mountain islands are below sea level, and given this consideration Mauna Kea
Mauna Kea ( or ; ; abbreviation for ''Mauna a Wākea''); is a dormant volcano on the island of Hawaii. Its peak is above sea level, making it the highest point in the state of Hawaii and second-highest peak of an island on Earth. The peak i ... ( above sea level) is the world's tallest mountain and volcano, rising about from the Pacific Ocean floor.
The highest mountains are not generally the most voluminous. Mauna Loa () is the largest mountain on Earth in terms of base area (about ) and volume (about ). Mount Kilimanjaro is the largest non-shield volcano in terms of both base area () and volume (). Mount Logan is the largest non-volcanic mountain in base area ().
The highest mountains above sea level are also not those with peaks farthest from the centre of the Earth, because the figure of the Earth
Figure of the Earth is a term of art in geodesy that refers to the size and shape used to model Earth. The size and shape it refers to depend on context, including the precision needed for the model. A sphere is a well-known historical approxim ... is not spherical. Sea level closer to the equator is several miles farther from the centre of the Earth. The summit of Chimborazo, Ecuador's tallest mountain, is usually considered to be the farthest point from the Earth's centre, although the southern summit of Peru's tallest mountain, Huascarán
Huascarán () ( Quechua: Waskaran), Nevado Huascarán or Mataraju is a mountain in the Peruvian province of Yungay ( Ancash Department), situated in the Cordillera Blanca range of the western Andes. The southern summit of Huascarán (Huascará ..., is another contender. [
] Both have elevations above sea level more than less than that of Everest.
* List of mountain ranges
List of peaks by prominence
This is a list of mountain peaks ordered by their topographic prominence.
The prominence of a peak is the minimum height of climb to the summit on any route from a higher peak, or from sea level if there is no higher peak. The lowest ...
* List of ski areas and resorts
* Lists of mountains
* Seven Summits