A abundance is a ample landform that stretches aloft the surrounding acreage in a bound breadth usually in the anatomy of a peak. A abundance is about steeper than a hill. The adjective montane is acclimated to call aerial areas and things associated with them. The abstraction of mountains is alleged Orography. Exogeology deals with all-embracing mountains, which in that annex of science are usually alleged montes (singular—mons). The accomplished abundance on Earth based from sea akin is Mount Everest (8,848 m (29,029 ft)) in the Himalayas of Asia. The accomplished accepted abundance in the Solar System is Olympus Mons on the planet Mars at 21,171 m (69,459 ft). Mountains and abundance ranges on Earth are about formed by the movement and/or alternation of lithospheric plates.
Friday 24 February 2012
Definition
There is no universally accustomed analogue of a mountain. Elevation, volume, relief, steepness, agreement and chain accept been acclimated as belief for defining a mountain.2 In the Oxford English Dictionary a abundance is authentic as "a accustomed acclivity of the apple apparent ascent added or beneath abruptly from the surrounding akin and attaining an distance which, almost to the adjoining elevation, is absorbing or notable."2
Whether a landform is alleged a abundance may depend on acceptance amid the bounded people. The accomplished point in San Francisco, California, is alleged Mount Davidson, admitting its acme of 300 m (980 ft), which makes it ten anxiety abbreviate of the minimum for a abundance by American designations.citation needed Similarly, Mount Scott alfresco Lawton, Oklahoma is alone 251 m (823 ft) from its abject to its accomplished point
.
Definitions of "mountain" include:3
Height over abject of at atomic 2,500 m (8,202 ft
);
Height over abject of 1,500 m (4,921 ft).–2,500 m (8,202 ft). with a abruptness greater than 2
degrees
Height over abject of 1,000 m (3,281 ft).–1,500 m (4,921 ft). with a abruptness greater than 5 degrees
Local (radius 7,000 m (22,966 ft). acclivity greater than 300 m (984 ft)., or 300 m (984 ft)–1,000 m (3,281 ft). if bounded (radius 7,000 m (22,966 ft). acclivity is greater than 300 m (984 ft
).
By this definition,which? mountains awning 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 acreage accumulation is aerial and 10% of bodies alive in aerial regions.4 Most of the world's rivers are fed from abundance sources, and added than bisected of altruism depends on mountains for water.56
Whether a landform is alleged a abundance may depend on acceptance amid the bounded people. The accomplished point in San Francisco, California, is alleged Mount Davidson, admitting its acme of 300 m (980 ft), which makes it ten anxiety abbreviate of the minimum for a abundance by American designations.citation needed Similarly, Mount Scott alfresco Lawton, Oklahoma is alone 251 m (823 ft) from its abject to its accomplished point
.
Definitions of "mountain" include:3
Height over abject of at atomic 2,500 m (8,202 ft
);
Height over abject of 1,500 m (4,921 ft).–2,500 m (8,202 ft). with a abruptness greater than 2
degrees
Height over abject of 1,000 m (3,281 ft).–1,500 m (4,921 ft). with a abruptness greater than 5 degrees
Local (radius 7,000 m (22,966 ft). acclivity greater than 300 m (984 ft)., or 300 m (984 ft)–1,000 m (3,281 ft). if bounded (radius 7,000 m (22,966 ft). acclivity is greater than 300 m (984 ft
).
By this definition,which? mountains awning 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 acreage accumulation is aerial and 10% of bodies alive in aerial regions.4 Most of the world's rivers are fed from abundance sources, and added than bisected of altruism depends on mountains for water.56
Characteristics
Tall mountains ability into the colder layers of the atmosphere. They are appropriately accountable to glaciation, and abrasion through frost action. Such processes aftermath the aiguille shape. Some mountains accept arctic lakes, created by melting glaciers; for example, there are an estimated 3,000 arctic lakes in Bhutan. Mountains can be breakable and
weathered, altering their characteristics over time.
Tall mountains accept altered acute altitude at the top than at the base, and will appropriately accept altitudinal zonation of ecosystems. At the accomplished elevations, copse cannot grow, and whatever activity may be
present
will be of the aerial type, akin tundra.7 Just beneath the timberline line, one may acquisition subalpine forests of needleleaf trees, which can bear cold, dry conditions.8 In regions with dry climates, the addiction of mountains to accept college precipitation as able-bodied as lower temperatures additionally provides for capricious conditions, which in about-face leads to differing flora and fauna.79 Some plants and animals begin in these zones tend to become abandoned back the altitude aloft and beneath a accurate area will be brusque and appropriately constrain their movements or dispersal. On the added hand, birds, actuality able of flight, may booty advantage of montane habitats and drift into a arena that would contrarily not accommodate adapted habitat.10 These abandoned ecological systems, or microclimates, are accepted as sky islands.11
weathered, altering their characteristics over time.
Tall mountains accept altered acute altitude at the top than at the base, and will appropriately accept altitudinal zonation of ecosystems. At the accomplished elevations, copse cannot grow, and whatever activity may be
present
will be of the aerial type, akin tundra.7 Just beneath the timberline line, one may acquisition subalpine forests of needleleaf trees, which can bear cold, dry conditions.8 In regions with dry climates, the addiction of mountains to accept college precipitation as able-bodied as lower temperatures additionally provides for capricious conditions, which in about-face leads to differing flora and fauna.79 Some plants and animals begin in these zones tend to become abandoned back the altitude aloft and beneath a accurate area will be brusque and appropriately constrain their movements or dispersal. On the added hand, birds, actuality able of flight, may booty advantage of montane habitats and drift into a arena that would contrarily not accommodate adapted habitat.10 These abandoned ecological systems, or microclimates, are accepted as sky islands.11
Fold mountains
Bend mountains are the best accepted blazon of mountains. They are formed due to blow of two plates, causing folding of the Earth's crust. Examples of bend mountains are the Himalayas of Asia and the Alps in Europe.citation needed
Fault-Block mountains
As the name suggests, fault-block mountains or accountability mountains are formed back blocks of bedrock abstracts accelerate forth faults in the Earth's crust. There are two types of block mountains, namely the aerial and tilted. Aerial mountains accept two abrupt sides; whereas, the agee blazon has one abrupt ancillary and a affable angled side. Examples of fault-block mountains are begin in the Sierra Nevada abundance ambit of the western United States.
Volcanic mountains
Agitable mountains are formed due to agitable eruptions area magma bags up on the apparent of the Earth. Examples of volcanoes accommodate Mount Fuji in Japan and Mount Pinatubo in the Philippines. Inactive or abolished agitable abundance accommodate Mount Elbrus in Russia, Mount Kinabalu in Malaysia, Cotopaxi in Ecuador and Aconcagua in Argentina/
Dome mountains
Arch mountains are formed back the hot magma rises from the crimson and uplifts the above sedimentary band of the Earth's crust. In the process, the magma is not erupted, but it cools bottomward and forms the amount of the mountain. They are alleged arch mountains due to their actualization that resembles a arch shape. An archetype of a arch abundance is Navajo Abundance in the U.S. accompaniment of Utah.
Geology
A abundance is usually produced by the movement of lithospheric plates, either orogenic movement or epeirogenic movement. Compressional forces, isostatic boost and advance of ablaze amount armament apparent bedrock upward, creating a landform college than the surrounding features. The acme of the affection makes it either a acropolis or, if college and steeper, a mountain. The complete heights of appearance termed mountains and hills alter abundantly according to an area's terrain. The above mountains tend to action in continued beeline arcs, advertence tectonic bowl boundaries and activity. Two types of abundance are formed in this way depending on how the bedrock reacts to the tectonic forces, — bend mountains or fault-block mountains. Other abundance architecture processes accommodate volcanoes and sea attic spreading.
Fold mountains
Compressional armament in continental collisions may account the aeroembolism arena to thicken and fold, with actual affected both upwards and downwards. Since the below close continental band "floats" (cf iceberg) on the denser crimson rocks beneath, the weight of any crustal actual affected advancement to anatomy hills, plateaus or mountains charge be counterbalanced by the airiness force (see isostasy) of a abundant greater aggregate affected bottomward into the mantle. Thus the continental band is commonly abundant thicker below mountains ( sometimes alleged "mountain roots"),16 compared to lower lying areas. However, in abounding continental collisions (e.g. the Himalayas) allotment of one abstemious may artlessly override the other, crumpling in the action with the overridden band basic abundant of the support. Mountains may analogously be partly accurate by amphibian band subducted below the continental band (e.g. the Andes as the Nazca bowl flows below the South American Plate).
Fault-block mountain
Block mountains are created back ample areas are broadly burst up by faults creating ample vertical displacements. This accident is adequately common. The aerial blocks are block mountains or horsts. The amid alone blocks are termed graben: these can be baby or anatomy all-encompassing breach basin systems. This anatomy of mural can be apparent in East Africa, the Vosges, the Basin and Range arena of Western North America and the Rhine valley. These areas generally action back the bounded accent is analytic and the band is thinned.
Rock that does not accountability may fold, either symmetrically or asymmetrically. The upfolds are anticlines and the downfolds are synclines: in agee folding there may additionally be collapsed and chaotic folds. The Jura Mountains are an archetype of folding. Over time, abrasion can accompany about an antagonism of relief: the bendable upthrust bedrock is beat abroad so the anticlines are absolutely lower than the tougher, added aeroembolism bedrock of the synclines
.
Rock that does not accountability may fold, either symmetrically or asymmetrically. The upfolds are anticlines and the downfolds are synclines: in agee folding there may additionally be collapsed and chaotic folds. The Jura Mountains are an archetype of folding. Over time, abrasion can accompany about an antagonism of relief: the bendable upthrust bedrock is beat abroad so the anticlines are absolutely lower than the tougher, added aeroembolism bedrock of the synclines
.
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