Plate Tectonics
core (divided into the inner core and the outer core)
mantle
crust
Layer | Description |
|---|---|
Inner core | The inner core is 2900 km below the Earth’s surface, in the centre of the Earth, and is the hottest layer. It is spherical and solid and made up of iron and nickel. Its temperatures can reach 5500°C. |
Outer core | The outer core is the layer surrounding the inner core. It is made of liquid iron. |
Mantle | The mantle is the layer of the Earth which makes up 84% of its volume. It is also the thickest section at approximately 2900 km thick. The mantle is made up of different layers. The upper mantle is hard but below that is semi-molten rock called magma. |
Crust | The crust is the outer layer of the Earth on which we live. It is the thinnest layer and is between 5 and 90 km thick. |
The crust of the Earth is not made up of one solid piece – it is split into plates which float on the upper portion of the mantle. There are two types of plate:
dense oceanic crust
less dense thick continental crust
These plates move slowly and either move apart, towards or past each other.
The point at which these plates meet is known as a ‘plate margin’. It is at the plate margins where the most tectonic activity and tectonic hazards, such as volcanoes and earthquakes, occur.
There are two theories as to why these plates move. The first, and most common, theory is that the plates move due to convection currents in the Earth’s mantle. This is where the heat from the Earth’s core causes magma to rise. As it nears the Earth’s surface, it then cools and sinks. This circular motion causes the plates in the crust to move.
core (divided into the inner core and the outer core)
mantle
crust
Layer | Description |
|---|---|
Inner core | The inner core is 2900 km below the Earth’s surface, in the centre of the Earth, and is the hottest layer. It is spherical and solid and made up of iron and nickel. Its temperatures can reach 5500°C. |
Outer core | The outer core is the layer surrounding the inner core. It is made of liquid iron. |
Mantle | The mantle is the layer of the Earth which makes up 84% of its volume. It is also the thickest section at approximately 2900 km thick. The mantle is made up of different layers. The upper mantle is hard but below that is semi-molten rock called magma. |
Crust | The crust is the outer layer of the Earth on which we live. It is the thinnest layer and is between 5 and 90 km thick. |
The crust of the Earth is not made up of one solid piece – it is split into plates which float on the upper portion of the mantle. There are two types of plate:
dense oceanic crust
less dense thick continental crust
These plates move slowly and either move apart, towards or past each other.
The point at which these plates meet is known as a ‘plate margin’. It is at the plate margins where the most tectonic activity and tectonic hazards, such as volcanoes and earthquakes, occur.
There are two theories as to why these plates move. The first, and most common, theory is that the plates move due to convection currents in the Earth’s mantle. This is where the heat from the Earth’s core causes magma to rise. As it nears the Earth’s surface, it then cools and sinks. This circular motion causes the plates in the crust to move.
