Mountain, plateau, and plain are land features of the earth’s surface produced by the deformation of its crust.
About 27% of the earth’s surface is covered by the mountains.
Mountains are uplifted parts of the surface of the earth which are much higher than the surrounding areas.
But not all the elevated or uplifted areas are mountains.
For example, in Tibet, the elevated part, about 4500 meters high above sea level, is called a plateau and not a mountain.
It takes millions of years to form a Mountain Range.
Mountains are the elevated portions of the earth’s surface, with steep slopes and small summits rising over 1000 meters and formed throughout millions of years.
Mountain ranges, consisting mainly of raised folded sedimentary rocks, are called Fold Mountains.
When these rocks are subjected
Due to horizontal compressive forces for millions of years, these rocks get bent into up and down folds.
This leads to the formation of anticlines and synclines. Such earth movements occur from time to time and lift the folds to a considerable height which results in the formation of Fold Mountains.
Some fold mountains of the world are the Himalayas (Asia), the Alps (Europe), the Rockies (North America) and the Andes (South America).
These are known as young fold mountains.
Some of these mountain ranges continue to rise, for example, the Himalayas.
Block Mountains are formed from the motions of the inner earth.
As the stress forces operate on the rocks they build faults in them.
If the land is elevated above the surrounding areas between the two nearly parallel faults it forms a block mountain.
It can also occur when landfalls on the outer side of the faults leaving an elevated block between them.
The rocks that make up the fault levels can be smooth or even folded.
Block Mountain is also called a horse:
Examples of Block Mountains:
The Vosges (France)
Black Forest Mountains (Germany)
Sierra Nevada (North America)
The interior of the earth is extremely hot.
Due to high temperature deep inside the earth rocks turn into molten magma.
When this molten rock material is ejected to the earth’s surface during a volcanic eruption, it accumulates around the vent and may take the form of a cone.
With each eruption, the height of the cone rises and it assumes the shape of a mountain.
Since these mountains are formed by the accumulation of volcanic material, they are termed as volcanic mountains.
Examples of the mountains:
Mount Mauna Loa in Hawaii Islands
Mount Popa in Myanmar
Vesuvius in Italy
Cotopaxi in Ecuador
Fuji Yama in Japan
The weathering and different agents of erosion – rivers, winds, glaciers, etc. are constantly acting on the earth’s crust.
The process of erosion depends on the shape and structure of the rocks.
Due to the agents of erosion, the softer rocks of the upland are eroded much more rapidly than the areas of harder rock.
After thousands of years, soft rocks are worn down into the sand and the hard rocks are left standing up in the area that has been reduced in height.
These are called residual mountains.
The residual mountains are also called relict mountains.
Examples of Residual Mountains in India are the Nallamala hills, Mahendragiri hills, the Aravali hills, the Javadi hills, the Veliconda hills, and the Palkonda range.
Economic significance of mountains
Large resources of minerals are found in the mountains.
Coal and limestone deposits are found in the Appalachian range in the United States.
On mountain slopes, tea and coffee plantations and some fruit orchards are grown.
Hydroelectricity is produced in the mountain regions from the waters of perennial rivers.
Mountainous countries like Japan, Italy, and Switzerland, suffering from coal shortages, have created hydroelectricity.
Perennial rivers rising in the snow-fed or heavily rain-fed mountains are an important source of water.
The rivers from the high mountain area bring silt and sediment to the lower valleys.
This helps in the formation of fertile plains.
Northern India’s great alluvial plain was formed by rivers Ganga, Sutlej, and Brahmaputra.
The mountain ranges serve as natural political boundaries between countries and to a certain degree defend them against invasions.
The Himalayas have formed a political frontier between India and China.
Mountainous areas have lower temperatures.
They serve as a climatic divide between two adjoining regions.
The Himalayas act as a barrier to cold winds coming from Central Asia to the Indian subcontinent.
The Himalayas also push the Southwest Monsoon to rise and induce precipitation on its southern slopes.
The pleasant climate and the beautiful scenery of the mountains have led to their development as centers of tourist attraction.
Shimla, Nainital, Mussoorie, and Srinagar are some of the important hill stations of India which attract tourists all over the world.