Quetzalcoatl

A mountain is a topographic structure significant in positive Relief, located at the surface of Astre S of the telluric type (telluric Planet, satellites like the the Moon), and generally forming part of a assembly line . In term of description, one often retains two criteria to give the name of mountain to a positive relief: the Altitude on the one hand, but also the Uneven on the other hand, must be consequent, if not one will speak rather for example about Colline. In common language, one also often uses terms Synonyme S such as Sommet, Pic, Mont, Aiguille, etc It exists a great diversity of geological structures which can carry the name of mountain : crumplings rock, Volcano S credits or extinguished, reliefs of the sea bed… More the high mountain of the Solar system is thus the Olympus Mons, Volcan shield located on Mars, with a difference in 27 km height between its top and its base. On Ground, the highest mountain is the Everest with 8,845 km if one considers the difference between his top and the Sea level, or the Mauna Kea with 10,230 km if one selected the difference between his top and its base which is underwater.

Characteristics and formation

altitude of a terrestrial mountain is the height of its top compared to the Sea level. The importance of a mountain can be also measured by the difference in altitude between its top and the grounds surrounding.

A mountain is always formed thanks to forces which upwards modify gravitating balance (Geoid, or fields of equal gravity) by moving (or while adding) rocks. Imbalance thus created causes a positive relief, and by isostatic compensation (floating of the Earth's crust on the coat) a thickening of the crust (which can pass from a usual thickness of 30 km has more than 60 km). Two principal mechanisms make it possible to find a state of balance (null relief): extension (observed in the the Alps, the Basin and Arranges West of the the United States, in the the Andes, with the Tibet, in the chain hercynienne…) and the erosion. These two mechanisms cause a crustal thinning, and generally cause a reduction in the relief (absolute and relative).

Orogenesis

See also: Orogenesis

The Orogénèse (literally “birth of the relief”) can have several causes, but the principal one is due to the tectonic movements . The Subduction of a oceanic plate under a oceanic plate or continental form a Cordillera (the Andes cordillera, the Rocky Mountains). The collision of two continental plates can follow and create a chain of collision (the the Alps, the the Caucasus, the the Himalayas. The Earth's crust is thickened by faults and folds being expressed on all the scales (of the continental scale on a microscopic scale).

The presence of a thermic anomaly can also cause the formation of a relief by the contribution of material (Volcan) and/or by the modification of the density (and thus buoyancy) of the crust or the Lithosphère (hotter/less dense). The continental Crust being lighter than the lithospheric Coat subjacent, most of crustal thickening is absorbed with the interface crust/coat (the Moho is deeper). This thickening causes an increase in the relief, and generally a local increase in erosion. Erosion can also be responsible for the creation of relief by isostatic answer. An assembly line can also be created on a border of transforming Plaque (taking down), or extensive (borders Rift; the relief is created by heating effect)

Morphology of the mountains

The morphology of an assembly line depends on various factors:
  • the nature of the rocks (the tender rocks give reliefs softer than hard stones);
  • climate, and in particular intensity, the nature and the distribution of precipitations, like presence or not of Glacier;
  • the speed of deformation (vertical and horizontal movements of the rocks).

An assembly line activates generally presents important slopes and sharp-edged forms, whereas an inactive assembly line generally presents softer forms. This simplistic classification is not however any more topicality.

The highest mountain on the Ground is the mount Everest in the the Himalayas (8844.43 meters with the top of the sea level), or the volcano Mauna Kea with Hawaii which emerges from 4206 meters to the top of the sea, with its base 5500 meters under the sea level (either almost 10000 meters of relief). Highest in Europe is the mount Elbrouz in the the Caucasus (the Mont Blanc not being more the high summit but of Western Europe). More the high mountain known to date in the Solar system is the Olympus Mons on Mars, building volcanic 26 height km for a diameter of 600 km.

Some famous mountains: the K2, the Annapurna, the Cervin, Ben Nevis, the Kilimandjaro, the Mount McKinley, Mount Pink, Mount Whitney.

Erosion in mountain

On an assembly line scale, erosion is a powerful agent of distribution of the masses; in particular, the isostatic answer to erosion causes a vertical movement to the top of the rocks, and possibly a rising of the tops (if the relationship between the erosion of the tops and the erosion of the valleys allows it).
  • the action of snow and freezing occurs on the high slopes.
  • the action of the glaciers: A Glaciated valley is a valley which was dug by a glacier. Under the effect of its own weight, the glacier slips, moves (up to one meter per day for the Glacier of Let us work) and uses the rock. The field of Plasticity of the Ice being particularly wide, the mass of ice of a glacier runs out slowly under the effect of gravity. It involves with it Moraine S frontal or side. The origin of the moraines makes debate among the specialists: the ultraglacialists estimate that they are produced by the erosion of the glacier. The antiglacialists think that they are only transported by the glacier. After the withdrawal of the glacier, there remain only pads sometimes covered by the forest.

With the end of the last glacial period, the glaciers withdrew and modelled glaciated valleys (or valley in " U").
Freezing manages to output blocks in the cracks of the rock. The Appalachian Mountains gave their name to a type of relief, the Appalachian Relief, which indicates the vestiges of an old strongly flush mountain. Long corridors extend rectilinear spines parallel to. The Appalachian Cluse S form narrow passages through the links of the montagne.
The torrent S carry and produce blocks, rollers, gravels (size ranging between 4 mm and 4 cm), of the coarse Sable S, fine sands.

Forms of the relief in mountain:

  • Circus
  • Needle S: Needles of Chamonix, the Thick, the Meije
  • glaciated valleys, valleys hanging
  • bolt S
  • umbilical point: “left widened flat-bottomed glaciated valley, between two bolts” in Brownish Roger (to dir.), words of the geography , page 357. They give place to postglacial lakes like those of the Le Bourget (France) or the Lake Garda (Italy).

Assembly lines (nonexhaustive)

An assembly line is the meeting of several mountains side by side.

Téthysien system

The mountains of this system result from closing the Téthys ocean since the Crétacé. This closing was caused mainly by the collision between the plates African and Indian with Eurasia since the Eocene .

Alpine chains

The opening of various oceanic basins in the Mediterranean (Ligure sea, between the Corsica and the Provence, Tyrrhenian Sea between Corsica, Sicily, Sardinia and Italy, Sea of Alboran between Spain and Morocco, Aegean Sea between Greece and Turkey etc) complicates the geology and the geographical distribution of these chains.

Chain of the Pyrenees

The the Pyrenees are a mountainous chain between the Mediterranean (Cape de Creus) and the Atlantic Ocean (the Bay of Biscay), separating France and Spain and sheltering the principality of Andorre. The principal exception to this rule is formed by the Val of Aran, which depends on Spain but is located on the northern slope of the solid mass and the Spanish enclave of the town of Llívia. In orography, among the anomalies, is included the Cerdagne fall located on the southern slope of the chain, but shared between France and Spain.

The chain of the Pyrenees crosses 6 French departments of is in west which are: the the Eastern Pyrenees, the Aude, the Ariège, the Haute-Garonne, the Hautes-Pyrénées and the Yrénées-Atlantiques which belong to three areas Aquitaine, the Midday-Pyrenees, Languedoc-Roussillon. It crosses the Spanish autonomous communities of Catalogne, of Aragon, Navarre and Euskadi (Spanish Basque Country).

Chains of the Middle East

Chains perish-Himalayans

System of the American cordillera

The American cordillera is resulting from the subduction since the Crétacé of the peaceful plate under the plates North-American (Rocky Mountains, of the Alaska to the California) and South American (the Andes, of the Ecuador in the South of the Chile).

Rocky Mountains

The Rocky Mountains extend from the Canada to the Mexico, while passing by the the United States of America.

Andes cordillera

The Andes cordillera extends on several countries from South America: Chile, Peru, Ecuador, Argentinian, Colombia and Bolivia.

Other systems perish-peaceful

System hercynien

Other systems

Traditional activities in mountain

The mountain is the place of many traditional activities: exploitation of wood in low altitude (less 1  500 m), the Bovine breeding of S or Caprine S in the Mountain pasture S (of 1  500 with 2  500  m) summer, which often gives place to the production of Fromage S, which can be preserved a long time in altitude, like the Reblochon in Savoy.

The mining is also current, like that of the Fer in the solid mass of Belledonne in Dauphiné, until the middle of last century.

Sports of mountain

The winter

The summer

The mountains of the solar system

The Earth is not the Astre to only have mountains, because it belongs to the family of the Astre S of the telluric type, which have a hard crust, and consequently can have assembly lines . They are the telluric planets (Venus, Mars), and the satellites like the the Moon or Io. More the high mountain of the Solar system is thus the Olympus Mons, Volcan shield located on Mars, with a difference in 27 km height between its top and its base.

See also: List of the tops and mountains of the Moon

See too

Random links:George Darwin | Masone | Raymond Grant | Fabien Levy | Taruia