Download
1 / 23
230 likes | 337 Views
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 we find volcanoes. These are shown by red dots. Is there a pattern that you can describe?.
E N D
This map shows the plate boundaries again, and it also shows where we find 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 you think 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: • Do earthquakes and volcanoes appear all over the earth’s surface • or only in certain places? • Is there a recognisable pattern to where earthquakes seem to occur? • Which areas of the earth seem to be at the highest risk from • earthquakes?
We can take our understanding a little further. For example: Moves in a different way to this one This plate boundary How…..?
This is called a constructive plate boundary Now write down: • How the plates move. • 2. What happens when they move. At this plate boundary, the plates move apart very slowly. This causes earthquakes. As they move, magma rises up, and if it reaches the surface it will form a volcano.
This is called a destructive plate boundary At this plate boundary, the plates move together very slowly. As they rub together this causes a lot of friction. Friction leads to earthquakes, and can also cause volcanoes because of the heat.
Constructive Destructive Conservative 3 Types of Plate Margin (Divergent) Tensional (Convergent) Compressional (Transform) 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 crust destroyed. 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 Mid Atlantic Ridge.
Destructive plate margin The Mid Atlantic Ridge is a constructive 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 frictioncauses melting. This molten rock forces its way to the surface to form volcanoes.
Conservative plate margin Part of the San Andreas Fault Where crust is neither produced nor destroyed as the plates slide horizontally past each other.
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 • Some plate boundaries are known as constructive. Explain the processes that take place at constructive plate boundaries. (4) • 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) • 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)
