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thumb Mount Cook, a mountain in New Zealand
A mountain is a landform that extends above the surrounding terrain in a limited area. A mountain is generally much higher and steeper than a hill, but there is considerable overlap, and usage often depends on local custom. Some authorities define a mountain as a peak with a topographic prominence over an arbitrary value, for example the Encyclopędia Britannica requires a prominence of 2,000 feet (610 m).
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 upwards, 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 topography. The major mountains tend to occur in long linear arcs, indicating tectonic plate boundaries and activity. Mountain creation tends to occur in discrete periods, referred to as orogenies (orogeny). Two types of mountain are formed depending on how the rock reacts to the tectonic forces - block mountains or fold mountains.
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. 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 AfricaEast Africa is a region generally considered to include the countries of Djibouti, Eritrea, Ethiopia, Kenya, Somalia, Tanzania, and Uganda. Madagascar, is also included. Some parts of East Africa have been renowned for their concentrations of wild animals, the VosgesVosges Details Information Number88 Region Lorraine Prefecture Epinal Subprefecture Neufchateau, Saint-Die-des-Vosges Population Total 1999 Density Ranked 60th 380,952 65 /km² Area5,874 km Arrondissements 3 Cantons 31 Communes 515 President of the general, the Basin and RangeThe Basin and Range Province is a particular type of topography that extends east from the Sierra Nevada all the way to the Colorado Plateau, in the states of Arizona, California, Idaho, Nevada, New Mexico, Texas, and Utah in the southwestern United State province of Western North AmericaNorth America is the third largest continent in area and the fourth ranked in population. It is bounded on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the south by the Caribbean Sea, and on the west by the North Pacific Ocea and the RhineAt 1,320 km (820 miles), the Rhine River ( German Rhein French Rhin Dutch Rijn is one of the longest rivers in Europe. Its name is derived from the Celtic word renos (meaning "raging flow"). Together with the Danube it formed most of the northern frontier valley.
Where rock does not fault it folds, 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 rock of the synclines.
The HimalayanTibetan plateau and the Taklamakan plain to the north. The Himalaya (the Himalayan Range is a mountain range in Asia, separating India and the Northern Areas of Pakistan on the south and southwest from the vast Tibetan plateau (now part of China) on the n mountain range with Mount EverestEverest is the highest mountain on Earth (as measured from sea level). The summit ridge of the mountain marks the border between Nepal and Tibet. In Nepali the mountain is called Sagarmatha ( Sanskrit for "forehead of the sky") and in Tibetan Chomolangma. Heights of mountains are generally given as heights above mean sea levelFor considerations of sea level change, in particular rise associated with possible global warming, see sea level rise''. Mean sea level (MSL) is the average height of the sea, with reference to a suitable reference surface. Defining the reference level ,. The highest mountain on Earth is Everest, 8850 m, set in the world's most significant mountain range, the Himalayas. Other definitions of height are possible. The peak that is farthest from the centre of the Earth is Chimborazo in Ecuador. At 6,272 m above sea level it is not even the tallest peak in the Andes, but because the Earth bulges at the equator and Chimborazo is very close to the equator, it is 2,150 m further away from the Earth's centre than Everest. The peak that rises farthest from its base is Mauna Kea on Hawaii, whose peak is over 9,000 m above its base on the floor of the Pacific Ocean.
The tallest known mountain in the solar system is Olympus Mons, located on Mars.
Sufficiently tall mountains have very different climatic conditions at the top than at the base, and will thus have different life zones at different altitudes on their slopes. The plants and animals of a zone are somewhat isolated when the zones above and below are inhospitable, and many unique species occur on mountainsides as a result. Extreme cases are known as sky islands.
Mountains are not generally favored for human habitation; the weather is harsher, less food is available, and there is little level ground suitable for farming. Most mountains of the world have been left in their natural state, and are today primarily used for recreation. Some mountains are very difficult to climb, and offer spectacular views. Some people therefore enjoy the sport of mountaineering. Mountains are also the site for the sport of downhill skiing. People engaging in these activities often stay at mountain resorts built for the purpose.