Year 10 exams: tectonics revision

Bingo!

Ways to revise

Is this map clearer or not? Why?

This map shows the plate boundaries again, and it also shows where wefind volcanoes. These are shown by red dots.

Is there a pattern that you can describe?

All the dots and circles on this map show earthquakes. What do youthink the bigger circles show?

Can you see any links between this map and the last one?

Now make sure that you answer the key questions:

1. Do earthquakes and volcanoes appear all over the earth’s surfaceor only in certain places?

2. Is there a recognisable pattern to where earthquakes seem to occur?3. Which areas of the earth seem to be at the highest risk from

earthquakes?

We can take our understanding a little further. For example:

This plate boundary Moves in a different wayto this one

How…..?

Now write down:

1. How the plates move.2. What happens when they move.

This is called a constructive plateboundary

At this plate boundary, the plates moveapart very slowly. This causes earthquakes.As they move, magma rises up, and if itreaches the surface it will form avolcano.

This is called a destructive plateboundary

At this plate boundary, the plates movetogether very slowly. As they rubtogether this causes a lot of friction.Friction leads to earthquakes, and canalso cause volcanoes because of the heat.

3 Types of Plate Margin

• Constructive

• Destructive

• Conservative

(Divergent)

(Convergent)

(Transform)

Tensional

Compressional

Passive

From memory:

• Sketch and label a diagram of destructive (convergent) and constructive (divergent) plate bounday

Constructive plate margin

At the plate margins, new crust is being formed and old crustdestroyed. Along the Mid Atlantic Ridge, the plates are being pulled apart and molten rock, or magma, rises up from the mantle and sets hard on the ocean floor. In some places this occurs on land, as in Iceland which sits on the MidAtlantic Ridge.

Destructive plate margin

The Mid Atlantic Ridge is aconstructive plate margin. Most volcanoes occur at destructive plate margins. Here, the old crust is forced back down into the mantle in the subduction zone. Massive friction causes melting. This molten rock forces its way to the surface toform volcanoes.

Conservative plate margin

Where crust is neither produced nor destroyed as the plates slide horizontally past each other.

Part of the San Andreas Fault

Hotspots

Sometimes volcanoes (volcanic arcs) form at hotspots as well as at constructive and destructive margins. At a hot spot, the convection currents are very strong and heat becomes localised under the crust in the centre of a plate. The Hawaiian islands are an example, forming in the middle of the Pacific plate.

Sample exam questions related to plate tectonics

1. Some plate boundaries are known as constructive. Explain the processes that take place at constructive plate boundaries. (4)

2. Landform C shown on Figure 4a is an area of fold mountains. Explain how they are formed. You may use a diagram to help your answer. (4)

3. Explain how volcanoes form over hotspots. Use an annotated diagram or diagrams in your answer. (4)

Case studies: Montserrat and San Francisco-List 5 key facts you need to remember

Montserrat San Francisco

Examples of exam questions

• Choose a volcanic eruption or an earthquake you have studied. Explain the effects of the volcanic eruption or the earthquake on the people and the environment. (6)

• Choose a volcanic eruption or an earthquake you have studied. Explain the cause of the volcanic eruption or the earthquake. (6)