Unit 1 Physical Geography: The Restless Earth

1. Unit 1 Physical Geography: The Restless Earth Unit Lessons Why is the earth’s crust so unstable? What happens at plate margins? How are our highest and deepest places created? How do people use an area of fold mountains? How and where are volcanoes created? How do volcanoes affect people? How can we monitor volcanoes and predict eruptions? What is a supervolcano? What are earthquakes and where do they occur? What were the causes, effects and responses to the Kobe earthquake? What were the causes, effects and responses to the Port au Prince earthquake? Why is a tsunami hazardous? Independent study An account of the uses of fold mountains and adapting to life in Livigno, The Alps A report of the eruption of Mount St Helens, USA on 18th May 1980 A comparison of the earthquakes in Kobe, Japan and Port au Prince, Haiti

2. L How are our highest and deepest places created? Learning Objectives To know how and why fold mountains form at collision boundaries To know how and why ocean trenches form at destructive subduction margins Key terms:Geosyncline, collision boundary, destructive-subduction boundary

3. Starter • Acting out Margins • Use your hands to actout what happens at a destructive subduction, constructive and conservative margins • Talk each other through the stages! • Help? Use your diagrams 2 mins

4. Quick Draw… • You have 10 seconds… to draw the 4 layers of the earth • You have 20 seconds… to give two differences between oceanic and continental crust • You have 30 seconds… to draw and label a destructive subduction margin

5. Destructive subduction Destructive collision Our Highest and Deepest Places • The highest places on Earth are fold mountains. • The deepest places on Earth are ocean trenches. • Both fold mountains and ocean trenches result from plates moving together. • Where fold mountainsandocean trenches are found together they are a result of destructive-subduction • Where fold mountains are found by themselves they are a result of destructive collision

6. Destructive subduction Destructive collision A map to locate the world’s young fold mountains and ocean trenches Direction of plate movment Fold mountains Ocean trenches Ocean trenches form at destructive subduction margins (oceanic plate sinks beneath continental plate e.g. Pacific Plate and North American Plate) Young fold mountains form at bothdestructive subductionmargins and destructive collision margins (where two continental plates collide e.g. African plate and Eurasian plate)

7. Fold mountains in more depth • Formed in last 65 million years, young fold mountains are the highest areas of our planet. • Ranges include the Himalayas, the Rockies, the Andes and the Alps. • Older fold mountains like the Cumbrian mountains have been worn down via erosion • Found at destructive (subduction) and destructive (collision) plate margins The Alps, Europe’s highest fold mountains.

8. Young fold mountains: How they form 1. Geosynclines are huge depressions found naturally on the ocean floor Ocean Geosyncline 3. Sediments are compressed and turned to sedimentary rocks like limestone 2. Rivers deposit sediment in these geosynclines Rivers 4. Plates are forced together at destructive margins (can be subduction or collision) 5. Sedimentary layers are forced upwards into fold mountains

9. Oceantrenches in more depth • Form the deepest parts of the Earth • Occur at destructive (subduction) margins • As oceanic plate is subducted beneath the continental plate creates deep ocean trenches. The deepest ocean trenches are created by oceanic-oceanic subduction. Ocean trench • Mariana trench is deepest part of the world’s ocean. • Created by the subduction of the Pacific plate beneath the Mariana plate (oceanic-oceanic)

10. Challenger Deep: The deepest part of Mariana Trench and the lowest part of the Earth • Challenger Deep is the lowest elevation on the Earth’s crust at 11,035 metres deep. • You can fit Mount Everest in the Mariana Trench and there would still be over a mile of water left above it.

11. ExamTechnique Explanation Explanation is an important technique. It is done best using clear, ordered sentences. Higher level explanation will include key terms and diagrams. • Explain how fold mountains are formed? (4 marks) Fold mountains form when two plates collide at destructive margins.Sediments are deposited on the ocean floor in geosynclines. Layers of sedimentary rock are created. As the two plates collide the sedimentary rock is forced upwards into fold mountains (e.g. Alps, Europe) Sediments deposited in geosyncline Layers of sedimentary forced upwards by plates colliding, forming fold mountains

12. Destructive subduction ExamTechnique Explanation Explanation is an important technique. It is done best using clear, ordered sentences. Higher level explanation will include key terms and diagrams. 2. Explain how ocean trenches are formed? (4 marks) At a destructive subduction margin the oceanic plate sinks beneath the continental plate. As it subducts, the seabed forms a deep trench. Ocean trench