1. The Earth’s Structure

2. Interior Layers Earth’s interior is comprised of 4 layers:
3 solids and 1 liquid
1. Crust
2. Mantle
3. Outer Core
4. Inner Core

3. The Crust
Outermost layer – made of the lightest materials – rock, soil & seedbed
Divided into continental crust and oceanic crust. Thickness ranges from 8km beneath oceans to 40km beneath continents.
Continents are relatively light ‘blocks’ floating high on the upper mantle
Seafloor is made of basalt – a denser rock that presses deeper into the mantle
Rocks beneath the crust are called magma but when they reach the surface are called lava
The outpouring of lava known as volcanic eruptions are mainly confined to zones of weakness in the crust
The zones are frequently shaken, often violently by rapid movements in the crust and these movements are referred to as earthquakes
The zones of weakness divides the crust into several large pieces called plates

4. The Mantle
Upper mantle and lower mantle – 2900km thick (approx. 84% of the earth’s volume)
Temperature ranges – 500 degrees Celsius near crust to degrees celcius near outer core
Primarily solid, but the rock is so hot that parts of the mantle ‘flow’ under pressure
Hot rock rises and cooler rock descends creating slow moving currents
Composed of magnesium, iron, aluminium, silicon and Oxygen

5. The Outer Core
Liquid layer above the inner core – shell of molten iron, 2300km thick
Cooler than inner core – but still scorching hot at approximately degrees Celsius
Mostly iron, plus sulphur and nickel
Electrically conducive liquid – creates earth’s magnetic fields.

6. The Inner Core
Centre of the earth – deepest layer, 6250 km under the surface
A solid ball of an iron allow (sulphur & nickel traces)
Solidified state due to intense pressure
2400km in diameter, high pressure, white hot like the sun – approx degrees Celsius

7. The Earth’s Structure