La corteza y la tectónica de placas.

El interior de la Tierra.

Las capas de la Tierra.
Podemos dividir el interior de La Tierra en tres capas concéntricas:

1.       La más interior es el Núcleo, que a su vez se divide en una capa interna, sólida, y una capa externa liquida. Se corresponde con un 15% de la masa terrestre.

2.       La siguiente capa es el Manto, formado por materiales muy diversos (rocas y metales) parcialmente fundidos, aunque la parte superior es solida.

3.       La corteza, es la capa externa que ocupa un 1% de La Tierra. Está compuesta de rocas sólidas, como el basalto y el granito.

Además, de estas tres capas podemos distinguir la Litosfera, formada por la corteza y la parte superior del manto. Su principal característica es que es sólida (el nombre litosfera, significa “esfera de piedra” en griego) y flota sobre el manto compuesto, lo que hace que la corteza se quiebre, se hunda o levante.

La corteza terrestre.

Sus principales características son:

1. Su anchura es muy desigual. En las partes más anchas (unos 70 km) da lugar a los continentes (corteza continental), mientras que las partes más estrechas (10 km) quedan cubiertas por los océanos.
   
2. No es lisa, aparecen en la misma diferentes formas de relieves. El punto más elevado de la corteza es el monte Everest, con 8.848 metros de altura, mientras que el punto más profundo es la fosa de las Marianas con 11.022 metros de profundidad.
3. No es estable, puesto que está cambiando constantemente como consecuencia de las fuerzas internas y externas que la afectan.

La deriva de los continentes.

La corteza terrestre está dividida en una serie de gigantescos bloques que flotan sobre el manto, moviéndose.

Hace unos 200 millones de años, todos los continentes estaban unidos en un único supercontinente Pangea,  pero luego se divieron, separándose, y dando origen a los continente actuales.

Placas continentales son los bloques en los que se encuentra dividida la corteza terrestre. Los limites entre las placas son zonas con una intensa actividad volcánica y sísmica.

Vídeo deriva continental

Dorsales oceánicas son las cordilleras submarinas que se encuentran en el imite entre dos placas.

the earth's landforms.

Basic components of the physical enviroment. Landforms.

1.        Landforms of Surface relief.

We can distinguish four basic relief forms on the continents and islands.

a).Plains, extensive áreas of flat or gently undulating land which are located at an altitude of less than 200 metres above sea level.

African plain.

b).Plateaus, elevated plains which are located at altitudes of more tan 200 metres above sea level.

Columbia Plateau.

c). Mountains. Elevated landforms which have an altitude of more tan 600 metres and very steep slopes. Can be:

-Old, then have rounded forms and are calle massifs.

-Young, with pointed forms.

 
K-2, Himalaya.

-Normally are grouped into large groups, called ranges or sierras.

d).Depressions: sunken áreas which correspond to sunken blocks of terrain.

Can be:

-Depressed areas between mountains or plateaus called valleys.

 -Elongated depressions excavated by the rivers called river valleys.

-Lakes, a depression filled by water, such as the Caspian Sea.

Diagram of continental landforms.

2.       Landforms below sea level.

We can distinguish several basic forms of the relief bellow the waters of the oceans:

•       Continental shelf, a gente slope that extends from the continents beneath the sea waters.

•       Continental slope: Sharp decline between the continental shelf and the abyssal plain.

•       Continental margin, pronounced step which connect the continental shelf with the abyssal plain.

•       Abyssal plain, huge extensións of flat terrain located between the continental shelfs with a depth of between 4. 000 and 5. 000 metres.

•       Oceanic ridges, underwater mountains systems of several thousands metres of height.

•       Oceanic trench, narrow elongated drepressions which cut the abyssal plains.

Diagram of surface landforms.

3.       Coastal relief.

Coasts are areas of contact between the surface of the continents and the oceans and seas. Depending of their height  can be: cliffs, raised terrain or , beaches, low-lying terrain.

We can distinguish the following forms of reliefs:

•       Beaches: flat surfaces found along the sea shore, are formed by the acumulation of sediments.

•       Cliffs: elevated areas with a very steep side located on a coast.

•       Capes or headlands, areas where the coast juts into the sea or land surfaces that are partially surrounded by the sea.

•       Gulfs, areas where the sea is partially enclosed by  the Earth.

•       Estuaries, river valleys which have been flooded by the sea.

•       Fjord, a glacial valley which have been flooded by the sea.

•       Delta a coastal landform located at the mounth of a river, formed by the accumulation of sediments.

Comparision of an estuary and a delta.
Video about the origin of deltas and estuaries.

•       Peninsula, extension of land surrounded by water on all sides except one.

• Ithsmus, is the extension of land which links the peninsula to the continent.

Diagram of the main coastal landforms.

Activity:

1. Write down the name of the landform next to the definition:

UNIT 1. THE RELIEF.

With an A	Huge extensións of flat terrain located between the continental shelfs with a depth of between 4. 000 and 5. 000 metres.
Contains  a B	Flat surfaces found along the sea shore, are formed by the acumulation of sediments.
With a C	An area where the coast juts into the sea or land surfaces that are partially surrounded by the sea.
With a C	Elevated areas with a very steep side located on a coast.
With a C	The exterior layer of the Earth, is made up of solid rock.
With a D	A coastal landform located at the mounth of a river, formed by the accumulation of sediments.
With an E	Sudden movements of the Earth’s crust caused by the clash of two tectonic plates.
Contains an F	A glacial valley which have been flooded by the sea.
With a G	Areas where the sea is partially enclosed by  the Earth
With a E	River valleys which have been flooded by the sea.
Contains an I	Is the extension of land which links the peninsula to the continent.
With an L	A depression filled by water
With a M	Elevated landforms which have an altitude of more tan 600 metres and very steep slopes.
With an M	Old mountains which have rounded forms.
With an O	The process that explain the apparition of mountains. It occurs in the area where two tectonic plates come into contact.
With a P	extension of land surrounded by water on all sides except one.
With a P	Extensive áreas of flat or gently undulating land which are located at an altitude of less than 200 metres above sea level.
With a P	Elevated plains which are located at altitudes of more tan 200 metres above sea level.
With an R	Large group of mountains.
With an R	Underwater mountains systems of several thousands metres of height.
With a T	Narrow elongated drepressions which cut the abyssal plains
With a T	Huge wave that appear as a consequence of a underwater earthquake.
With a S	Sharp decline between the continental shelf and the abyssal plain.
With a V	Sunken area of terrain located between mountains or plateaus
With a V	ruptures in Earth’s crust through which magma are released onto Earth’s Surface

You can find the solution here.