Revision notes - the Earth, causes and effects of Volcanoes and Earthquakes.

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Restless Earth


LinksHumans use rocks for building and fossil fuels for energy

Plants use carbon dioxide from the air and humans use oxygen

Weather can erode rocks


Humans, plants & animals need water to live


Water evaporates to form clouds in the atmosphere

Water can be stored underground in rocks


Average Density: 5.5 g/cm3

Radioactive decay of unstable elements (uranium & thorium) in the core & mantle cause geothermal heat which causes convection currents in the mantle & outer core. These make the tectonic plates move. This radioactive decay also generates the Earth’s magnetic field.

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The Earth’s Plates

Categorising Volcanoes

Magma Chamber

Main Vent

Secondary Vent

Volcanoes are formed when semi-molten rock called magma rises and forces its way through weaknesses in the crust and then as surface pressure builds up there is a volcanic eruption. When magma reaches the surface of the earth it turns into lava.

An active volcano is likely to erupt soon. An extinct volcano is considered unlikely to erupt. A dormant volcano isn’t currently active but has erupted within the last 1000yrs and may erupt again.

Cone volcanoes tend to be found at destructive plate boundaries and they are ...

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