The Full Wiki

mountain: Wikis

  

Encyclopedia

, Iran]] , 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 Orology.

There is no universally-accepted definition of mountain. In the United States, 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 the 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 990 feet, which makes it ten feet short of the minimum for a mountain in American appellation.

Other definitions of "mountain" include: [1]

  • 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 7km) elevation greater than 300m, or 300-1000m if local (radius 7km) elevation is greater than 300m

By this definition, 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.[2] Most of the world's rivers are fed from mountain sources, and more than half of humanity depends on mountains for water.[3][4]

The 50 tallest mountains in the world are in Asia.

Exogeology deals with planetary mountains, which in that branch of science are usually called montes (singular - mons). The highest known mountain in the Solar System is Olympus Mons on the planet Mars (elevation 21,171 m).

Contents

Characteristics

High mountains, and mountains located close to the Earth's poles, 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 3,000 glacial lakes in Bhutan. Mountains can be eroded and weathered, altering their characteristics over time.

in Greece.]]
mountain view in Switzerland ]]

Tall mountains have different climatic conditions at the top than at the base, and will thus have different life zones 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 islands 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 rate 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 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 hypoxia - 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 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.

Types of mountains

Main article: Types of mountains [[File:|thumb|left|The Matterhorn, the classic pyramidal peak ]] 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 processes and can be characterized by their glaciated features. Still others are typified by the faulting and folding of the Earth's crust, or by the collision of continental plates via plate tectonics (the Himalayas, for instance). Shape and placement within the overall landscape also define mountains and mountainous structures (such as butte and monadnock). Finally, mountains can be characterized by the type of rock that make up their composition.

Geology

Error: must specify an image in the first line

A mountain is usually produced by the movement of lithospheric plates, either orogenic movement or epeirogenic movement. The 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 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 isostasy). 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 volcanoes, including many apparently small islands that reach a great height above the ocean 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 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.

The mid-ocean ridges 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.

Gallery

See also

External links

A Climber's Glossary

References

  • Fraknoi, A., Morrison, D., & Wolff, S. (2004). Voyages to the Planets. 3rd Ed. Belmont: Thomson Books/Cole.

Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

Contents

English

A mountain (large mass of rock)

Etymology

From Old French montaigne, from Vulgar Latin *montanea, from Latin montānus (mountainous), from mōns (mountain).

Pronunciation

Noun

Singular
mountain

Plural
mountains

mountain (plural mountains)

  1. A large mass of earth and rock, rising above the common level of the earth or adjacent land.
  2. A large amount.
    There's still a mountain of work to do.

Derived terms

Related terms

Translations

External links

References

  • mountain in The Century Dictionary, The Century Co., New York, 1911
  • mountain in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913

Anagrams


Simple English

A mountain is a natural rise of the Earth's surface that usually has a "summit" (or "top"). It is usually steeper and taller than a hill. Mountains are often thought of as being a hill of over 600 metres (about 2,000 feet), but this thought is not the same in every country.

Mountains are important to life on Earth, because most rivers begin in mountains and carry water from the mountains down to the sea.

Contents

What is a mountain?

  • The highest point of a mountain is called the peak. A mountain's summit is the highest area on the mountain a mountain climber may reach, but a climber cannot reach the peak.
  • Britannica Student Encyclopedia says that the term "mountain' usually means a rise of over 2,000 feet (610 m)".[1].
  • The usual height for a mountain in England is 600 metres. In England, it is important to have a legal height because people have the "Right to Roam" in mountains, but they do not have the right to walk on other people's land. Even though mountains are defined by law, many people in England use the word "hill" even when they talk about very large mountains.
  • In the USA, even though there are many very tall mountains, the name mountain is often given to hills that may be only 100 feet high.
  • In Scotland, a mountain that is over 3,000 feet (914.4 m) is sometimes called a "Munro".
  • In Australia and some other places, the word "mountains" is also used to describe high land that is really a plateau and is flat on top, rather than having peaks.

Mountains can symbolize hard things to overcome or an obstacle. It may also symbolize loneliness, being brave, and more.

Form

The forming of a mountain is called orogeny. Mountains are formed when rock layers are pushed from opposite sides, and they push the crust up. A mountain range is a large group of mountains beside each other. There are four ways a mountain may be made:

  • fault
  • fold
  • plutonic
  • volcanic

Height

The height of a mountain is measured as distance above sea level. The tallness of a mountain is from the center.

Tallest mountains

The highest mountain in the solar system is the Olympus Mons (27 km) on Mars. The highest mountain in the world is Mount Everest (8,848m)which is in Nepal/Tibet in Asia. (The "tallest" mountain in the world is Mauna Kea, in Hawaii. The "height" of a mountain is measured from sea level, but the "tallness" of a mountain is measured from its base, even if under water.) The highest mountain in North America is Mount McKinley (6,194m) in Alaska in the USA. The highest in South America is Aconcagua (6,962m) in Argentina. For Africa, it is Kilimanjaro (5,963m) of Tanzania. In Europe, the highest mountain is in Russia called Elbrus (5,633m). Antarctica's highest mountain is Vinsin Massiff (5,140m). In Oceania, a mountain called Puncak Jaya (5,030m) is the highest there. This particular mountain is in Papua New Guinea / Indonesia.

Mountain types

There are five main types of mountains:

  • volcanic
  • dome
  • folded
  • plateau
  • fault-block

Some people say there are six types, as domed mountains can be a plutonic dome or a tectonic dome.

Volcanic mountains

Volcanic mountains are mountains that form when molten rock erupts onto the Earth's surface. They can either form on land or in the ocean. The Cascade Range in Washington, Oregon and northern California is made of volcanoes. Some of the largest volcanoes are on divergent boundaries, which form the mid-ocean ridges. The mid-ocean ridges have big volcanic mountain chains that run through the Atlantic, Pacific and Indian Oceans. The mountains in the mid-ocean ridges can actually grow tall enough to create islands such as Iceland or the Azores.

Other volcanic mountains can form over hot spots, which are pockets of magma beneath the crust that erupt onto Earth's surface. The Hawaiian Islands are actually the tops of really high volcanic islands that have formed over a hot spot on the sea floor. The main Hawaiian island is actually a volcano that is about 9 km above the ocean floor, with a base that is about 160 km wide. Almost 4 km of this island is above sea level.

Dome mountains

Dome mountains, like those in the Black Hills of South Dakota and the Adirondack Mountains of New York, are an unusual domish type of mountain that is formed when molten rock rises through the crust and push up the rock layers above it. This creates a circular dome on the Earth's surface. The molten rock later cools off and forms hardened rock. When the pushed up rocks are worn away, the hardened rock is shown. This hardened rock then wears away in places. When it wears away, it leaves mountains, and they are called dome mountains.

Folded mountains

Folded mountains make up some of the highest mountains in the world. Folded mountains commonly form along boundaries, where 2 continents meet. Some really complex folds can be found in parts of the Andes, Alps, Himalayas, Appalachians, and Russia's Ural Mountains. These long mountain chains also show lots of signs of folding.

Plateau mountains

Plateau mountains are formed a bit like folded mountains. They are large areas of flat topped rocks that have been lifted high above the crust by continental plates. Most plateaus are found near folded mountains.

Fault-block mountains

Fault-block mountains are formed when parts of the Earth's crust has been broken off into large block mountains. They are also formed when two blocks of land rise above or fall down leaving its middle part behind, and when magma pushes up by the lava and forces top layers of rock up with it. Domed mountains, although have broken and move up as a 'chunk'. A fault block mountain is a mountain or range formed as a horst when it was elevated between parallel normal faults. A horst is the raised fault block bound by normal faults.

References

Find more information on Mountain by searching one of Wikipedia's sister projects:

Dictionary definitions from Wiktionary
Textbooks from Wikibooks
Quotations from Wikiquote
Source texts from Wikisource

Error creating thumbnail: sh: convert: command not found
Images and media from Commons

News stories from Wikinews


Citable sentences

Up to date as of December 15, 2010

Here are sentences from other pages on Mountain, which are similar to those in the above article.








Got something to say? Make a comment.
Your name
Your email address
Message