When two plates collide or separate, magma can rise from the mantle to fill the space that opens in the crust – the vent. We call this an eruption, and it can be violent due to the great pressure that the magma is under in the mantle.
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When magma wells up from the magma chamber and reaches the surface, it cools and hardens. This is known as lava.
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After many eruptions, layers of lava and ash build up around the vent, and a cone-shaped mountain is formed with a crater at the top from which the lava flows.
The formation of a volcanic mountain
STAGE 1
STAGE 2
STAGE 3
A volcanic mountain
To watch a video that explains why magma erupts violently from a volcano, watch ‘Volcanoes Under Pressure’ (2:25) on YouTube.
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Managing information and thinking:
Identify the volcanic cone and crater in this photograph.
Fun Fact!
The word ‘volcano’ comes from the name of the Roman God of fire, Vulcan.
