The Structure of the Earth.

SOCIAL STUDIES. Summaries in English.

UNIT 2

LANDFORMS

STRUCTURE OF THE EARTH

If we moved from the surface into the centre 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 in the middle and represents 85% of the 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 surface of the planet is covered with water from the Oceans. Most of the oceans are in the Northern hemisphere.
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.
1

In the Continents.

Mountain
Mountain Range
Glaciers
Valley
Plain
Plateau
Depression

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.
2
When rocks are rigid they break and make Faults.
Other times when plates collide earthquakes and volcanos are produced. Vocanos 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 landform. Rivers form valleys. Oceans and seas also alter the aspect of coasts with beaches and cliffs.

Wind. Can transport small particles of sand and form dunes.

Living Beings. Plants can alter the landscape. Its roots can break rocks. Corals also modify the aspect of the coast with coral reefs.
Human beings modify the aspect of our planet with buildings and agriculture. Very often the action of man on the landscape has very negative consequences.






3