Structure of the Earth (WJEC GCSE Chemistry: Combined Science)

• The structure of the Earth consists of four main layers:
• Inner core
• Outer core
• Mantle 
• Crust

Structure of the Earth Diagram

The Earth consists of the inner core, outer core, mantle and crust

Composition of the Earth

Layer	Thickness (km)	Composition
Inner core	1400	A solid and dense layer composed of iron and nickel at around 5500 °C
Outer core	2100	A liquid layer composed of iron and nickel at about 5000 - 5500 °C
Mantle	2900	A layer of semi-molten rock which is less dense than the outer core
Crust	Variable	A layer of solid rock which is less dense than the mantle

• The thickness of the crust ranges from 5 to 70 km thick, with an average thickness of 20 km