Revisons 1

Plate tectonics: Plate movement

Volcanoes

Map Reading

Plate is the broken pieces of Earth’s crust

that float above the mantle.

Plate boundary is the boundaries where the

plates move.

Plates move in 3 ways:

1. Plates move towards each other (convergent)

2. Plates move away from each other (divergent)

3. Plate move slide past each other (transfrom)

When the lower part of the mantle is heated, the molten magma rise & spread out beneath the plate.This drag the plate away from each other.

Then the spreading magma cools and once it is cool, it sinks. This drags the plate towards each other.

The continuous rising of hot magma & sinking of cool magma set up convection current.

Answer these questions without looking at your

notebook!

What is mean by ‘Plate’?

What is mean by ‘Plate boundary’?

How do plates move?

Why do plates move?

Distributions/locations of volcanoes.

Volcanoes are usually found along or near the plate boundaries

Volcanoes are concentrated in a belt around the Pacific Ocean. The belt of volcanoes is called the Pacific Ring of Fire

Volcanoes mainly occur along destructive plate boundaries (where plates move towards each other).

Ans: Eurasian plate and Pacific plate

Y

Convergent plate boundary

Y

Y

Along the convergent plate boundaries, convectional currents of magma in the upper mantle converge and sink, causing a continental plate and an oceanic plate to collide.

Along the subduction zone where the plates meet, magma is produced by the melting of the subducted plate in the mantle. This magma rises to the surface of the Earth forming Volcanoes.

Advantages/positive impacts of living near volcanoes:

The dramatic scenery created by the volcanic eruptions attracts tourists. This brings income to the area. E.g. Mount Fuji in Japan.

The lava and ash deposited during an eruption breaks down to provide valuable nutrients for the soil. This creates very fertile soil which is good for agriculture. E.g. in Java and Deccan Plateau in India.

The high level of heat inside the Earth, close to a volcano, can provide opportunities for generating geothermal energy which could be used to generate electricity.

Volcanic areas are also rich in mineral deposits. E.g. diamonds of Kimberly in South Africa.

Disadvantages/negative impacts of living near volcanoes:

Many lives can be lost as a result of volcanic eruption.

If the ash and mud from the volcanic eruption mix with rain water or melting snow, fast moving mudflows are created. These flows are called lahars.

Lava flows and lahars can destroy settlements and clear areas of woodland and agriculture.

Human and natural landscapes can be destroyed and changed forever.