Geography Secondary group

Let's understand geography content with improving our learnin by practicing on few topics. 

Enjoy. 

Topic:1  Earth structure 

The diagram shows internal structure of the earth 

four layers of earth 🌎

1. The crust: is a thin outer layer of solid rocks. 

It is between 6 to 90 km thick.

The crust is divided into two parts.

A) Oceanic Crust (SIMA) made up of Silicon and Magnesium)

B) Continental Crust (SIAL) made up of Silicon and Aluminium.

2. Mantle

• it is the thickest layer of the earth, covering up to 2900 km.

• It is very hot reaching 5000°C.

• Materials inside mantle are in a semi-molten state closer to the crust and molten near the

core aallowing it to move or flow.

• These molten rocks are called magma and it forms hard rocks when it cools and solidify.

3. The outer core

• it is about 2000 km thick.

• It is very hot and denser.

• It is in a molten state.

4. Inner core

• it is about 1200 km thick

• It is extremely hot, but it is in a solid state because of the pressure that other layers put on it.

Differentiate between plate and plate tectonic

A plate/tectonic plate – is a large section of the earth crust that floats on the mantle.

Plate tectonic – refers to the movement and interaction of plates that are floating on the mantle and their

associated land forms.

Describe how convection current causes plate movement

• Convection current is heat currents caused by intense heat in the interior of the earth.

• Its caused when heated materials (lighter) in the mantle rises, while cooler materials (dense)

sinks.

Why does tectonic plate move?

• Due to convection current.

• Plate/crust float on the semi-molten state mantle.

• Heat from the mantle pushes convection current within the mantle upward

• If the convection current is moving in a particular direction, it will drag the section of the crust above it in the same direction and therefore cause plate movement.

Activity 

• Name and explain the main 4 layers of the Earth's structure.

• Name the force that is responsible for plate movement.

• Explain how tectonic plate move.