el relieve

The Earth’s relief is the combination of landforms which appear in Earth’s surface.

We can distinguish two phases in the evolution of the relief: formation and evolution. The formation and the evolution of the relief is the consequence of the action of a variety of internal and external forces:
-internal forces which explain the formation of the relief: orogenesis, earthquakes, volcanoes.
-external forces which explain the evolution of the relief: atmospheric elements, water and living beings.

Relief formation and its agents.

The relief is form by the earth’s internal forces which raise, sink or move blocks of terrain. The main internal forces are:

•       Orogenesis is the process of forming mountains. It occurs in the area where two tectonic plates come into contact.

Formation of the Himalayas

•       Earthquakes, sudden movements of the Earth’s crust caused by the clash of two tectonic plates.

Earthquakes for kids

•       Volcanoes are ruptures in Earth’s crust through which magma are released onto Earth’s Surface. Are located in áreas where two tectonic plates make contact.

Relief modification and its agents.

The modification of the relief is caused by the Earth’s external forces which produces:

Erosion, the wearing down of types of relief.

Movement of the eroded materials.

Sedimentation, the acumulation of eroded materials in specific areas.

The main Earth’s external forces are:

• Atmospherics elements, such as:

-Temperature, the rapid changes of temperature make the rocks expand and contract.

-Rainfall penetrates the cracks in the rocks and expands when freezes, breaking the rocks. Also transport the eroded materials.


-Wind erodes the rocks, breaking them down. Also transport the eroded materials.

Wind erosion

• Water, disolves certains components of the rocks, excavating valleys and ravines. Also transport the eroded materials.

Cliff falls into the sea due water erosion

•  Living beings. Vegetations and animals change the relief breaking the rocks.

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  Root wedging
  
  

  Human beings also modifies the relief by mining or building motorways

  

  The big Hole, Kimberley (Sout Africa):