SOCIAL STUDIES. Summaries in English.

UNIT 2

LANDFORMS

STRUCTURE OF THE EARTHestructura.jpg

If we moved from the surface into the center of our planet we would find 3 different layers.
  • Crust.It is the external layer; life developes on the crust. It represents only 1% of the total volume of our planet.

  • Mantle. It is the middle layer and represents 85% of Earth's total volume. Part of the mantle is molten rock.

  • Core. The deepest layer. There are both solid and liquid rocks under conditions of extreme temperature and pressure. The core is mostly iron.

CRUST AND TECTONIC PLATES



Most of the surface of the planet is covered with water from the Oceans. Most of the oceans are in the Northern hemisphere.
The crust is broken into pieces that move constantly at a speed of 2 to 20 cm a year.

LANDFORMS
Include different morphological alterations of the crust.


  • In the Continents.

Mountain
Mountain Range
Glaciers
Valley
Plain
Plateau
Depressionlandforms.jpg

  • On the Coast

Gulf
Bay
Beach
Cliff
Island
Peninsula
  • Under the Sea.

Abyss
Ocean Basin
Ocean Ridge

THE ORIGIN OF LANDFORMS

When Tectonic Plates move and collide (touch) the energy that emerges from the inside make the stones fold. This is the origin of mountains and mountain ranges.

When rocks are rigid they break and make faults.
Other times when plates collide earthquakes and volcanos are produced. Volcanos and earthquakes alter the aspect of landscapes.

LANDFORMS CHANGE

The landform is not always the same; it can be altered by the action of water, wind or living beings.

  • Water. The erosion of rivers can alter the aspect of landforms. Rivers form valleys. Oceans and seas form beaches and cliffs, which alter the characteristics of the coast.
  • Wind. Can transport small particles of sand and form dunes.
  • Living Beings. Plants can alter the landscape; their roots can break rocks. Coral also modify the aspect of the coast with coral reefs.
Human beings modify the landscape of our planet with buildings and agriculture. Very often the actions of humans on the landscape has very negative consequences.

If you want to learn more:
Landforms
Activities