Plate Tectonics

Transcript

Download transcript

Although the Earth's surface may seem very static, it's actually moving.

The rising and falling of heat deep inside the Earth causes convection currents.

Convection Currents

These can drag the plates apart, causing them to travel a few centimetres every year.

This might not seem much, but the effects are dramatic.

It's what causes earthquakes, produces volcanoes, creates mountains, and – over millions of years – moves whole continents.

These dramatic events all occur due to plate tectonics.

Plate Tectonics

And there are three different ways the plates can move.

They can pull apart push together or slide past each other.

When plates move apart, it is called a constructive boundary.

Constructive Boundary

These tend to occur under the sea.

As the plates move away from each other, molten magma rises up, which can cause a chain of volcanoes to erupt.

The magma eventually cools and forms new surface rock.

When plates move towards each other, there are two possible effects.

If the plates are both landmasses, both surfaces are pushed upwards, forming mountains.

This is a collision boundary.

Collision boundary:
Two continental plates
Crumples land upwards

But if an underwater and continental plate push together, the denser oceanic plate is forced underneath, in a process called subduction.

This is called a destructive boundary.

Destructive boundary:
Oceanic and continental plates.
Subduction zone

The subducted crust melts to form magma, which can trigger earthquakes and powerful volcanoes.

When plates move sideways, it's called a conservative boundary.

Conservative boundary:
Plates slide against each other

New land isn't created or destroyed, but they can produce severe earthquakes.

The movements of the plates, means landscapes are constantly being reshaped by the hidden heat deep within our planet.

Related films

Related glossary films