What is the Earth made from?What are Plate Tectonics?What happens at the different types of plate boundary?

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Cross section of the Earth

Inner Core

Mantle

Outer Core

Crust

The outer layer of the earth. It is a very thin layer ranging from 6-70km thick.

Layer of liquid made up largely of iron.

Due to the high temperature of this thick layer it has a consistency like jam! Temperatures range from 5000 0C near the core to 1300 0C just below the crust.

This is a solid layer and is also made up if iron. Temperatures can reach 5,500 0C

Why do the plates move?

Study of fossilsSimilar fossils are found on different continents. This is evidence that these regions were once very close or joined together.

Shapes of continents Some continents fit together like a jigsaw.

Africa

SouthAmerica

Pattern of rocksSimilar pattern of rock layers on different continents is evidence that the rocks were once close together or joined.

Evidence for continental drift

Continental drift

At a constructive plate boundary, two plates move apart. As the two plates move apart, magma rises up to fill the gap. This causes volcanoes. However, since the magma can escape easily at the surface the volcano does not erupt with much force.

Earthquakes are also found at constructive boundaries.

An example of a constructive boundary is the Mid-Atlantic Ridge.

Constructive plate boundary

A destructive plate boundary is found where a continental plate meets an oceanic plate.

The oceanic plate descends under the continental plate because it is denser. As the plate descends it starts to melt due to the friction caused by the movement between the plates. This melted plate is now hot, liquid rock (magma). The magma rises through the gaps in the continental plate. If it reaches the surface, the liquid rock forms a volcano.

Destructive plate boundary

Collision boundaries occur when two plates of similar densities move together (i.e. a continental plate and a continental plate). This causes the material between them to buckle and rise up, forming fold mountains.

The Himalayas are an example of a chain of fold mountains. They have been formed by the Indian plate colliding into the Eurasian plate.

Collision plate boundary

A good example of this type of motion is the San Andreas Fault which runs through California.

PLATES MOVING SIDE BY SIDEPLATES MOVING SIDE BY SIDE