Study of Mountains


Mountain with its classification

A mountain is described as a very steep land or hill rising to great heights above the land surrounding it. Mountains are classified into three main types depending on the forces that have formed them. Three main types of mountains are - Fold Mountains, Block Mountains and Volcanic Mountains.


Fold Mountains

Fold Mountains are the result of lateral compression of the earth's crust. They are the results of large-scale earth movements caused by stresses n the earth's crust. Such stresses may be caused by weight of the overlying rocks, movements in the mantle, the expansion or contraction of some of the earth, etc. These stresses subject the rocks to compressive forces, producing wrinkling or folding along the lines of weakness. The raising of folds makes the fold mountains.


Young fold mountains and old fold mountains

The fold mountains that have formed recently (the Himalayas, the Alps, the Rockies and the Andes) are known as the young fold mountains. Some fold mountains like the Urals, the Appalachians, the Nan Shan and the Tien Shan were formed much earlier. Such fold mountains are known as the old fold mountains. The Aravallis in India are considered to be one of the oldest fold mountains on the Earth's surface.


Block Mountains

The forces of faulting lead to the formation of block mountains. Due to tensional forces, cracks or faults may occur on the earth's crust. If two parallel faults occur, the land in between subsides to form a rift valley. If a block rises, it forms a horst or block mountain. Block mountains which have flattened summits are also called horst mountains.


Residual mountains

These mountains are formed out of the existing mountains i.e. Fold, Block or Volcanic Mountains. High Mountains are worn away by the agents of denudation i.e. wind, water, glacier, waves etc. The remaining part of these mountains is known as residual mountain. Examples are Namuli Mountains in Mozambique and Hanbori Mountains in Mali.


Block mountains

Block mountains are also formed due to faulting as a result of tensional  and compressive forces. When a part of the earth's crust is lifted between two parallel faults, it looks like a block. Such a landform is known as a block mountain. The hilltops of the block mountains are flat and the slopes are steep. Black forest in Europe, Meghalayan plateau of India are some examples.