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IAS Geography Notes: Endogenic Forces

Last Updated - April 10, 2017

IAS Exam is a 3-level exam starting with preliminary round followed by the Mains Exam and after that Personal Interview of the shortlisted candidates. The IAS Prelims is scheduled to be held on June 18, 2017.

Endogenic forces are one of the important topics in Geography of the year 2017-18. Horizontal and vertical movements caused by the forces coming from the origin of the earth is known as endogenic forces.

The earth’s surface is not plain, it’s distributed unevenly due to landforms like hills, mountains, plains, ravines, cliffs etc. The formation and deformation of hills, mountains, cliffs etc. are the continuous process which is influenced by the external (exogenic) and internal (endogenic) forces. These forces cause the stress and chemical changes on earth’s surface due to which changes occur on the surface of the earth.

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In this article, we will describe endogenic forces or internal forces in detail.


Endogenic Forces

The horizontal and vertical movements caused by the forces coming from the origin of the earth is known as endogenic forces. The origin of endogenic force is caused by the contraction and expansion of rocks due to variation in thermal conditions and temperature inside the earth. These forces are responsible for creation of many landforms.                                                                                                                        

Example: Mountain building forces, earthquakes, volcanism etc.

  • These forces play very important role in shaping the earth crust.
  • These forces are usually land building forces.
  • The energy behind the endogenic process originates from within the earth.
  • The energy is produced by radioactivity, rotational and tidal friction and primordial heat from the earth.
  • Folding and faulting or tectonic plates are the main process of endogenic forces.

Endogenic process includes:

There are a total number of seven plates which covers the earth’s crust. The movement of plates in different boundary leads to change in landforms. Given below are the types of movement plates shows.

  • Convergent boundary
  • Divergent boundary
  • Transform boundary

Read IAS Geography Notes: Erosion and Deposition - Action of Running Water and Groundwater


Difference between Endogenic and Exogenic Forces

Endogenic and exogenic forces are different from each other in terms of the movements they make and where they produced. Given below is the table of differences between them:

EndogenicExogenic
Produced within the origin of earth crustProduced on the surface of earth crust or above the surface.
These forces cause sudden movements or slow movements.These forces only cause slow movements.
The result is only visible when it causes sudden damage.Result is visible after millions and thousands of years.
Example: earthquake, building mountainsExample: erosional, depositional

Endogenic Forces can be divided into two sub categories-

IAS Geography Notes

1. Diastrophic

2. Sudden

1. Diastrophic Forces

The movement of solid material on the earth crust produces some forces which are refer as diastrophic. These forces are also known as constructive forces. The processes which includes movement, elevate or build portion of earth crust fall under the process of diastrophic. These forces affect large area of earth. It is a slow movement process which changes very gradually. Their effects become observable after thousand and millions of years.

Diastrophism includes the following:

  • Processes involving mountain building through folding and affecting long and narrow belts of the earth’s crust.
  • Processes involving upliftment or subsidence of large parts of the earth’s crust.
  • Earthquakes involving local relatively minor movements.
  • Involves horizontal movements of crustal plates.

The Diastrophic forces are subdivided in two categories as follow:

IAS Geography Notes

Epeirogenic Process

The occurrence of upliftment and subsidence of land due to the upward and downward movement is known as epeirogenetic movement. These movements are also called vertical movements. They usually form continents and plateaus. There are no changes occur in the horizontal structure of rock. These movements are caused by the forces coming from the origin of earth.

These movements are further classified into two categories:

  • Upward movement: Upward movement causes the upliftment of whole continental or the upliftment of the coastal land of continentals.
  • Downward movement: Downward movement causes subsidence of land area or the land area subsided below the sea level.

Orogenic Process

These movements are also known as horizontal movements. The formation of mountains caused by the horizontal forces are the result of orogenic movements. Horizontal forces are also known as tangential forces. These forces work in two different ways i.e. tensional and compressional ways.

Tensional force:

These forces work in opposite manner and create ruptures, cracks, fractures etc. in the crust of earth. These forces work in a horizontal manner.

  • Faulting: it is the displacement of rocks in upward and downward movement from their real position
  • Fault line: the line on which displacement of the fractured rocks take place.
  • Rift valleys: faulting result in the formation of valleys and Block Mountains which is formed by sinking of rocks between two parallel faults.

Compressional force:

These forces work towards each other and leads to the formation of folds. These forces lead to the bending of rocks and formation of Fold Mountains. This also leads to local rise or subsidence of crustal parts. Himalayas, the Rockies and the Andes are also formed by the process of compression.

2. Sudden Forces

These forces are the result of long period changes occurring inside the earth crust but the cumulative effects on earth surface are sudden. The affects sometimes lead to destruction. They show sudden and quick affects and can be seen in minutes. These sudden forces are also known as constructive forces.

Example: volcanic eruption leads to volcanic cones, fractures, lakes etc.

Earthquake (seismic activity)

Earthquake is an example of sudden forces which are happening all the time but are not noticed until it causes visible damage. The visible sudden changes are rapid shaking of earth due to the released energy of rocks. It is a natural phenomenon.

IAS Geography Notes

Volcanoes (volcanic activity or igneous activity)

It is also called magmatism. Volcano is an example of sudden movement which occurs due to plate movement. Volcano is a spacious hole in the surface from which the molten rock and gases and ashes eject. It is of two types extrusive and intrusive.

The erupted materials can contain:

  • Cinder- dark colored pieces
  • Pumice- bubbly, frothy hard rocks
  • Ash- grained particles

Metamorphism

It is an endogenic process. It leads to the formation of metamorphic rocks. It occurs when pressure and heat applied to the geological structures.

IAS Geography Notes

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