Mountains

Mountain is a type of Habitat or Biome which rises well above its surroundings and generally exhibits steep slopes, a relatively confined summit area and considerable inequalities of elevation. A Mountain is generally steeper and higher than a Hill. It is generally considered that for land mass to be qualified as a Mountain, it needs to be higher than 600 metres (2,000 feet). Those less than 600 metres are called Hills. Mountains are formed by the folding, faulting, or upwarping of the Earth’s surface due to the movement of plates. They can also be formed by the positioning of volcanic rock onto the surface. For example, the Himalayan Mountains where India meets the Eurasian Plate were formed by a collision between plates that caused extreme compressional folding and the uplifting of large areas. Mountains cover one-fifth of the Earth’s land surface, and occur in 75% of the World’s Countries. The height of a Mountain is measured as distance above sea level. The tallness of a Mountain is from the centre. A Mountain Belt is an area of Mountain which can be tens to hundreds of kilometres wide and hundreds to thousands of kilometres long. It stands above the surrounding surface, which may be a coastal plain, as along the western Andes in northern Chile, or a high plateau, as within and along the Plateau of Tibet in south-west China. Mountain Ranges or Chains are long chains or groups of Mountains. They can extend tens to hundreds of kilometres in length. A group of Mountain Ranges is called a 'Mountain System'. For example, the Mountain Systems of the United States include the Rockies and the Appalachians. A Mountain's 'Summit' is the 'Highest Area on the Mountain' and the 'Highest Point of a Mountain' is called the 'Peak'. A 'Seamount' is a Mountain rising from the ocean sea floor that does not reach to the water's surface (sea level), and thus is not an Island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a sea-floor of 1,000–4,000 metres depth. A 'Monadnock' or 'Inselberg' is an isolated rock hill, knob, ridge, or small Mountain that rises abruptly from a gently sloping or virtually level surrounding plain. Volcanic or other processes may give rise to a body of rock resistant to erosion, inside a body of softer rock such as limestone  which is more susceptible to erosion. When the less resistant rock is eroded away to form a plain, the more resistant rock is left behind as an isolated Mountain

1.  Basic Types of Mountains

1.  Fold Mountains (Folded Mountains) - These are the most common Mountain types. The world’s largest Mountain ranges are Fold Mountains. These ranges were formed over millions of years. Fold Mountains are formed when two plates collide head on, and their edges crumbled, much the same way as a piece of paper folds when pushed together. Fold Mountains are formed when two plates collide head on, and their edges crumbled, much the same way as a piece of paper folds when pushed together. The Himalayan Mountains were formed when India crashed into Asia and pushed up the tallest Mountain range on the continents.

Some of the Fold Mountains

• Himalayan Mountains in Asia.
• The Alps in Europe.
• The Andes in South America.
• The Rockies in North America.
• The Urals in Russia.

2.  Fault-Block Mountains - These type of Mountains are formed when faults or cracks in the Earth's crust force some materials or blocks of rock up and others down. Instead of the Earth folding over, the Earth's crust fractures (pulls apart). It breaks up into blocks or chunks. Sometimes these blocks of rock move up and down, as they move apart and blocks of rock end up being stacked on one another. Often Fault-Block Mountains have a steep front side and a sloping back side.

Some of Fault-Block Mountains

• The Sierra Nevada Mountains in North America.
• The Harz Mountains in Germany.

3.  Dome Mountains - Dome Mountains are formed when a large amount of magma pushes up from below the Earth's crust, but it never actually reaches the surface and erupts. Instead of bursting the magma pushes up overlaying rock layers. After some time the magma cools and forms a dome shape rock. The uplifted area created by rising magma looks like the top half of a sphere or ball, thereby giving it the name Dome Mountain. It also gets its name because the uplifted area is higher than its surroundings, erosion by wind and rain occurs from the top. This results in a circular Mountain range.

4.  Volcanic Mountains -Volcanic Mountains are created when magma (molten rock) deep within the Earth, erupts, and piles upon the surface. When the ash and lava cools, it builds a cone of rock. This material builds up around the Volcanic Vent is known as Volcanic Mountain.

Some of the Volcanic Mountains

• Mount St. Helens in North America.
• Mount Pinatubo in the Philippines.
• Mount Kea and Mount Loa in Hawaii.

5.  Plateau Mountains - Plateau Mountains are created when running water carves deep channels into a region, creating Mountains. Over billions of years, the rivers can cut deep into a Plateau and make tall Mountains. Plateau Mountains are usually found near Mountain. Because they are formed by erosion they are also known as Erosion Mountains. The Mountains in New Zealand are examples of Plateau Mountains.

2.  Types of Glacially Eroded Mountains

1.  Arête - An Arête is a thin, almost knife-like, ridge of rock which is typically formed when two glaciers erode parallel U-shaped valleys. The Arête is a thin ridge of rock that is left separating the two valleys. Arêtes can also form when two glacial Corries (walled semicircular basin) erode head-wards towards one another, although frequently this results in a saddle-shaped pass, called a 'Col'. The edge is then sharpened by freeze-thaw weathering. Where three or more Corries meet, a pyramidal peak is created. A Cleaver is a type of Arête that separates a unified flow of glacial ice from its uphill side into two glaciers flanking, and flowing parallel to, the ridge. Cleaver gets its name from the way it resembles a meat cleaver slicing meat into two parts.

Some of the Arêtes

• Knife Edge, on Mount Katahdin, Maine.
• Clouds Rest, in the Sierra Nevada, California.
• La Peineta, in the Andes of Los Ríos Region, Chile.
• Crib Goch, in Snowdonia National Park, Wales.

2.  Pyramidal Peak - Pyramidal Peak is a Mountain top that has been modified by the action of ice during Glaciation and frost weathering. It is a common shape for Mountain tops in well glaciated areas. It is formed by the walls of three or more adjacent steep-sided glacial basins, e.g. the Matterhorn in Switzerland. Ice fields at the head of glaciers develop U- or bowl-shaped basins in the sides of a Mountain called 'Corries'  (sometimes called cirques or cwms). These encroach on each other to produce ridges known as Arêtes. The joining together of three or more Arêtes forms a Peak. A peak has a sharp summit and steep slopes on at least three sides. A glacial horn takes the process to its limits, producing near vertical faces on all sides. In the Alps, "Horn" is also the name of very exposed peaks with slope inclinations of 45-60° (e.g. Kitzbüheler Horn). They are a common shape for Mountain tops in well glaciated areas.

Some of the Pyramidal Peak

• The Matterhorn in Zermatt, on the border between Switzerland and Italy.
• The Kitzsteinhorn near Kaprun in Salzburg, Austria.
• Mount Blanc above Chamonix in eastern France.
• Mount Thielson in Oregon, USA.

3.  Nunatak - A Nunatak is an exposed, often rocky element of a ridge, Mountain, or peak not covered with ice or snow within (or at the edge of) an ice field or glacier. The term is typically used in areas where a permanent ice sheet is present. Nunataks present readily identifiable landmark reference points in glaciers or ice caps. Lifeforms on Nunataks are frequently isolated by the surrounding ice or glacier creating unique habitats. Nunataks are generally angular and jagged because of freeze-thaw weathering, and can be seen to contrast strongly with the softer contours of the glacially eroded land below if the glacier retreats.

Some of the Nunataks

• Cântaro Magro, Serra da Estrela, Portugal.
• Starr Nunatak, on the coast of Victoria Land, Antarctica.

General Characteristics of Mountains

• Cold Climate with increase in Altitude - The temperature on Mountains becomes colder the higher the altitude gets. Air temperature drops about 3.5 degrees for every 1000 feet of elevation gain. At the foothills (near the bottom) there may be a tropical climate, whilst the peaks (the very top of mountains) may be covered in ice. The uppermost level of Mountains is often bare rock and snow. For example the Himalayas, the Rocky Mountains, the Andes etc. The snow on the top of Mountains remains all year round, because the temperature at the top of Mountains is lower than at the bottom. The higher the place is above sea level the colder it will be. This happens because as altitude increases, air becomes thinner and it is less able to absorb and retain heat. The cooler the temperature the less evaporation there is, meaning that there is more moisture in the air. Air pressure decreases with altitude. As a result of the reduced air pressure, rising air expands and cools.

• Prone to Glaciation and Erosion - Mountains are prone 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.

• Less Oxygen at higher Altitudes - There is less oxygen in the air at higher altitudes in Mountains. The Air pressure is less in Mountains, and less air pressure means less oxygen to breath. The concentration of oxygen at sea level is about 21% and the barometric pressure averages 760 mmHg (unit of atmospheric pressure). As altitude increases, the concentration remains the same but the number of oxygen molecules per breath is reduced. At 12,000 feet (3,658 meters) the barometric pressure is only 483 mmHg, so there are roughly 40% fewer oxygen molecules per breath.

• Decrease in Gravity - Gravity derives from the centre of the Earth and therefore its Gravitational Pull is strongest in areas which are located closest to its core. Since Mountain are located higher above sea level, the Gravitational Pull is weaker. Gravity decreases as the space between objects increases. Simply put when we are at the top of a Mountain the Earth exercises less of a pull as we are further away from the surface.

• Unpredictable Weather - Mountain weather conditions can change dramatically within hours. For example, there is no prediction as to when a clear sky will turn into  a thunder storm and in just a few hours the temperatures can drop from extremely high to a one which is below freezing. Mountains which reach higher than the clouds have extreme cold temperatures and high winds cause blizzards.

• Frequent Rainfall - Mountains tend to have much wetter climates than the surrounding flat land. They receive more rainfall than low lying areas because the temperature on top of Mountains is lower than the temperature at sea level. Winds carry moist air over the land. When air reaches the Mountain, it rises because the Mountains are in the way. As the air rises, it cools, and because cool air can carry less moisture than warm air, it releases the moisture resulting in rainfall.

• Varied Life Forms with Varying Altitude - The foothills of a Mountain may be covered in Broadleaved Forests; higher up, Coniferous Trees like Spruce and Pines appear. With the increase in altitude the conditions become inhospitable for trees and they virtually disappear. The highest parts of the Mountain support only sparse grasses and low-growing Alpine flowers. At even more high altitude this vegetation disappears and the peak is bare and rocky and can be covered in snow and ice.  Alpine plants in high Mountain regions are slow growers. The brief summers are spent building up food stores in their roots in order to survive the biting cold of winter. In spring, Alpine plants burst briefly into flower. Animals too vary with varying Altitudes in accordance with food they need which are limited to certain altitude of Mountains.

• Bleak Habitat for Animals - High Mountains are a bleak habitat for animal life. Food is scarce and the climate is very cold. Very few Animals are able to live here. Those that live here, have adapted to survive the bitter cold and by having thick woolly fur. They are also good climbers like the Mountain sheep, the chamois and ibex. They are very sure-footed and are therefore able to climb the jagged, craggy slopes. Snow Leopard which lives above the snowline in the Mountains of central Asia is one of the top predators preying on Ibex and Tahr. Golden eagle, Andean condor utilise the Mountain air currents to soar in the sky without using much energy. The Bearded Vulture or Lammergeier utilises the height of Mountains to break the the bones which it carries high up into the air and drops them on the rocks below to extract bone marrow which is it staple diet. Other Mountain Animals include Alpine Swift, Alpine Chough, Snow Finches, Brown Bear, Black Bear, Grizzly Bear, Mountain Lion etc.

• Effectors of Dry Areas - Mountains can affect the climate of nearby lands. In some areas, Mountains block rain, so that one side of a Mountain range may be rainy and the other side may be a desert. Much of airborne moisture falls as rain on the windward side of Mountains. This often means that the land on the other side of the Mountain (the leeward side) gets far less rain - an effect called a 'Rain Shadow' which often produces a Desert. The higher the Mountain, the more pronounced the rain shadow effect is and the less likely rain will fall on the leeward side. By the time the air gets to the leeward side of the Mountain it has already lost some of its moisture. Many of the deserts of the world are formed because of the lack of moisture blocked by the Mountains. The Gobi desert is located behind the Himalayan Mountain range in Asia.

Distribution

Mountains are found on all Continents and there are Mountains under the surface of the Sea as well.

Some Major Mountains of the World

1. Mount Everest in Asia.
2. Mount Kilimanjaro in Africa.
3. Mount Fuji in Japan
4. Mount Olympus in Greece.
5. Mount Kenya in Africa.
6. Mount McKinley in North America.

Some Major Mountain Ranges of the World

1. The Himalayas.
2. The Alps.
3. The Andes.
4. The Rockies.
5. The Karakoram.

Origin of Mountains

The Earth's Mountain Ranges have various ages of formation. Parts of the Himalayas are relatively quite young. Mountain building in this region of the world began about 45 million years ago when the continental plates of India and Eurasia converged on each other. The Himalaya Mountains are still actively being uplifted. The Appalachian Belt is quite old. Mountain building in this region of the World started about 450 million years ago. The process of Mountain building stopped in the Appalachians about 250 million years ago. The long passage of time without active uplift has allowed weathering and erosion to remove large amounts of bedrock from the Appalachians. These processes have also significantly lowered and rounded the peaks of the various Mountains found in this belt. Mountain building episodes in the North American Cordillera have been occurring over a very long period of time and still continue today. Some sedimentary rocks in the Rocky Mountain range (located on the eastern edge of the North American Cordillera) date to over a billion years old.

Importance of Mountains

• More than half of the world’s fresh water originates in Mountains, and all the World's major Rivers are fed from Mountain Sources. This water is stored in reservoirs and is linked to towns and cities.

• Mountains are home to approximately one-tenth of the world’s people. It has been estimated that 12% of the world's 6.8 billion people live in Mountain areas. That means there is about three-quarters of a billion (seven hundred fifty million) people living in Mountain areas.

• Mountains are also important habitat for a variety of Plants and Animals, some of which are unique to Mountains only.

• Mountains are used by farmers as grazing grounds for their cattle. Mountains also support other farming activities.

• Mountains are a major Tourist spots. According to one estimate about 100 million visitors visit the Alps each year. Mountains aid tourism and support the local economy. Mountains are places for leisure activities which includes mountaineering, paragliding, skiing, snow boarding, sledging, ice-fall climbing, snow-shoe Trekking, winter walking, ice skating etc.

• There are certain types of wood which can grow in Mountainous regions only. This wood is used for various purposes and it encourages Forestry.