What are Endogenic and Exogenic forces ? – IAS Geography Notes

Endogenic and Exogenic Forces

Endogenic forces have been a recurring and important topic in Geography for IAS entrance examinations. In this article, we will cover the crucial aspects of endogenic forces that are significant from the IAS preparatory aspect.

What are Endogenic and Exogenic forces?

Clearly, the surface of the earth is not flat but is rather unevenly spread out due to the presence of landforms including mountains, plains, hills, etc. These uneven landforms are formed and deformed over a period of time, in an ongoing process, due to the influence of internal and external forces from within and above the surface of the earth.

Simply put, we can define endogenic forces (internal) and exogenic forces (external) as the two major geomorphic forces that lead to the earth’s movements and gives shape to the earth’s surface.  

When these internal and external changes occur continuously, chemical changes and stress are triggered on the surface of the earth, which eventually leads to the formation of uneven terrains.

Endogenic Forces – Internal forces in detail

Endogenic forces or endogenetic forces are the forces that originate inside the earth, therefore also called internal forces. These internal forces lead to vertical and horizontal movements, and result in subsidence, land upliftment, volcanism, faulting, folding, earthquakes, etc.,

It includes the following features:-

  • Endogenic forces are land building forces that play a crucial role in the formation of the earth’s crust
  • These are also called internal forces as they form, originate and are located below the surface of the earth.
  • Primordial heat, radioactivity, tidal and rotational friction from the earth results in the creation of this energy.
  • The main processes involved under this are volcanism, folding, and faulting.
  • The endogenetic forces can be further broken down into two major forms:-
    • Slow movements: These are also referred to as Diastrophic forces. It results in changes over a period of time.
    • Sudden movements: As the name suggests, these are the visible movements, and includes significant landform changes like earthquakes and volcanic eruptions.

Let us cover these topics in detail below:-

Slow Movements (Diastrophic forces)

In simple terms, Diastrophic forces can be defined as the forces that are created due to the movement of the solid material on the earth’s surface. This includes all the processes that raise, move or build up the parts on the earth’s surface.

Diastrophism involves the following processes:-

  • Epeirogenic movements: this is the process of warping or upliftment of large parts of the earth’s surface.
  • Orogenic movements: this is essentially the process of mountain building that involves major folding, and affects the long as well as narrow belts of the surface.
  • Earthquakes that occur due to relatively minor local movements
  • The horizontal movements of the crustal plates, or plate tectonics.

Diastrophic forces can be primarily divided into two major movements. They are as follows:-

  • Orogenic movements
  • Epeirogenic movements

Let us understand orogenic movements first.

Horizontal Movements or Orogenic Movements have the following features:-

  • These movements are caused by the horizontal forces that act on the surface of the earth from side to side.
  • Orogenic movements or horizontal movements is also referred to as mountain building.
  • They can be categorized into two major forces:
    • Forces of tension.
    • Forces of compression.
  • Orogenic movements create tension to the strata’s horizontal layer, that further leads to massive structural deformation of the earth’s surface.

Let us move on to Vertical Movements now.

Vertical  Movements or Epeirogenic Movements have the following features:-

  • Epeirogenic movements are essentially responsible for the creation of plateaus and continents on earth.
  • These powerful movements occur from the center of the earth.
  • Vertical movements can be responsible for both the upliftment as well as the subsidence of the continent.
  • They cannot create variation in the horizontal rock strata unlike discussed in the previous type.

Difference between Endogenic and Exogenic Forces

Let us now quickly discuss the major points of difference between Endogenic and exogenic forces:

  • On the basis of origin
    • Endogenic forces originate from within the surface of the earth.
    • Exogenic or external forces are forces that occur on or above the earth’s surface.
  • Examples
    • Endogenic forces include earthquakes, mountain formation.
    • Exogenic forces include the tidal force of the moon, erosion.
  • Nature of movements
    • Endogenic forces can result in both slow and/or sudden movements.
    • Exogenic forces will always lead to slow movements.
  • Visibility
    • Endogenic forces produce after-effects that are visible only after it causes sudden damage.
    • Exogenic forces create changes visible over a period of thousands or millions of years.

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