Mountain

For the homonymous articles, to see Mountain (homonymy).
K2 in.

One mountain is a topographic structure in positive relief generally forming part of a "assembly line".

The altitude of a mountain is the height of its top compared to 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 modify gravitating balance (geoid, or fields of equal gravity) by déplacant (or while adding) rocks upwards. Imbalance thus creates causes a positive relief, and by isostatic compensation (floating of earth's crust on 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 , it Basin and Arranges West of the USA, in The Andes, with , in the chain hercynienne...) and it. These two mechanisms cause a crustal thinning, and generally causes a reduction in the relief (absolute and relative).

Synopsis

Orogenèse

orogenèse (literally "birth of the relief") can have several causes, but the principal one is due to the movements tectonics. subduction of a oceanic plate under a oceanic plate or continental form one cordillera ( Andes cordillera, them Rocky Mountains). The collision of two continental plates can follow and creer a chain of collision (them , it , it. earth's crust is thickened by faults and folds expressing itself on all the scales (of the continental scale has the microscopic scale).

The presence of a thermic anomaly can also cause the formation of a relief by the contribution of materiel (volcano) and/or by the modification of the density (and thus the flotability) of crust or of lithosphere (hotter/less dense). continental crust being lighter than it [ lithospheric coat ] ] under-jascent, the greatest part of crustal thickening is absorbed has the interface croûte/manteau (it 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. Assembly lines can also be creates on a border of plate transforming (taking down), or extensive (borders rift; the relief east creates by heating effect)


Morphology of the mountains

The morphology of assembly lines 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).

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

The highest mountain on is the mount Everest in (8848m with the top of the sea level), or the volcano Mauna Kea with Hawaii who emerges from 4206 with the top of the sea, with his base 5500m under the sea level (either almost 10000m of relief). Highest in Western is it in , or the mount Elbrouz in according to geographical definitions' of Europe. The highest mountain known to date in is itOlympus Mons on , 26 height km volcanic building for a diameter of 600 km.

Some famous mountains: K2, itAnnapurna, it Cervin, Ben Nevis, it Kilimandjaro, the mount McKinley, Pink mount, mount Whitney.

Assembly lines (nonexhaustive)


Téthysien system

The mountains of this systems result from closing the Téthys ocean since Cretaceous. This closing has pricipalement éte caused by the colision between the plates African and Indian with Eurasia sinceEocene.

  • Alpine chains

The opening of various oceanic basins in the Mediterranean (sea Ligure, between and , Tyrrhenian Sea enter , Sicily, Sardinia and , Sea of Alboran enter and , Sea Égée enter and etc.) complicates the geology and the géographieque distribution of these chains


System of the American cordillera

The American cordillera results from the subduction since Cretaceous peaceful plate under the plates North-American (Rocky Mountains, of with ) and South American (The Andes, ofEcuador in the South of ).


Another systems perish-peaceful

Hercynien System


Another system

  • (, , )
  • The Ural ()
  • Transantarctic chain


Traditional activities in mountain

The mountain is the place of many traditional activities: exploitation of wood in low altitude (less 1500m), the breeding of bovines or of caprine in mountain pastures (of 1500 with 2500m) the summer, which often gives place to the production of , which can be preserved a long time in altitude, like in . Mining is also current, like that of in the solid mass of Belledonne in Dauphiné, until the middle of last century.

Sports of mountain

The winter

The summer

See too


: internal structure · hydrosphere · relief · atmosphere
Hill · Dune · Mountain · Beach · Plain · Plate
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