The Restless Earth Revision Notes

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The centre of the Earth, the core, is made up of iron and nickel.

Around the core is the mantle which is made up of molten rock that moves slowly. Convection currents occur in the mantle.

The outer layer of the Earth is the crust which is also the thinnest layer of the Earth (about 20 km).

The crust is made up of two plates which are either continental or oceanic. Continental plates are thicker and less dense however oceanic plates are thinner and more dense. The plates are moving because convection currents in the mantle occurs. Plates meet and join at plate margins/boundaries.

Destructive:

Two plates move towards each other

When an oceanic and continental plate move towards each other, the dense oceanic plate is forced beneath the continental plate. This creates volcanoes and ocean trenches. Ocean trenches are very deep sections of the oceanic floor where the oceanic plates sinks.

Constructive:

Two plates move away from each other. Magma rises from the mantle and fills the gap forming new crust hence oceanic plates are younger than continental.

Conservative:

Two plates move sideways (past each other in the opposite direction or in the same direction at different speeds). Crust isn't created or destroyed

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