Processes and 2, 3 and 4 mark questions Restless Earth Processes and 2, 3 and 4 mark questions We will be turning our books into revision guides. Glue in contents sheet showing which topics and case studies we will be doing. Glue onto the front of your book. For now just do the Restless Earth Section. We will call this Chapter 1!

Processes Do you know your layers? Play until 2.38. Then it moves on to convection currents and plate movement.

Convection currents Draw a diagram to show how they work. Convection currents in the magma drive plate tectonics. Heat generated from the radioactive decay of elements deep in the interior of the Earth creates magma (molten rock) in the asthenosphere. The asthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the Earth that extends to 2900 km. Convection currents Draw a diagram to show how they work. Can you explain? Large convection currents in the asthenosphere transfer heat to the surface, where plumes of less dense magma break apart the plates at the spreading centers, creating divergent plate boundaries. As the plates move away from the spreading centers, they cool, and the higher density basalt rocks that make up ocean crust get consumed at the ocean trenches/subduction zones. The crust is recycled back into the asthenosphere.

Plate Boundaries It all starts with Alfred Wegener’s theory of continental drift. Plates move! Can you name some plates? Play from 2.50 Can you describe what happens? The most important is to be able to explain why volcanoes and earthquakes happen at each boundary. Could you give an example of each?

Explain why volcanoes occur at CONSTRUCTIVE or DESTRUCTIVE plate margins. Usually a 4 or 6 mark question. Possibly with a diagram. Oceanic crust Continental crust Key words to use would be CONVECTION CURRENTS SUBDUCT and sequence your answer! Firstly….and then….

You may also be asked why earthquakes happen at specific plate margins. Key word CONVECTION CURRENTS, FRICTION and PRESSURE released. Sequencing and explain. Use the train… FIRSTLY,.....secondly, and then….

With the aid of a diagram explain the formation of... What about a composite cone? http://study.com/academy/lesson/what-is-a-shield-volcano-definition-facts-examples.html

Explain how young fold mountains are formed. The formation of fold mountains Where an area of sea separates two plates, sediments settle on the sea floor in depressions called geosynclines. These sediments gradually become compressed into sedimentary rock. When the two plates move towards each other again, the layers of sedimentary rock on the sea floor become crumpled and folded. Eventually the sedimentary rock appears above sea level as a range of fold mountains. Again don’t forget to use sequencing! Firstly.. Where the rocks are folded upwards, they are called anticlines. Where the rocks are folded downwards, they are called synclines. Severely folded and faulted rocks are called nappes.

Lets have a go at some questions. Complete the paragraph below to explain why earthquakes happen at conservative plate margins (4 marks) At conservative plate boundaries, plates move .................................. each other. They .................................. each other. The plates often stick and .................................. builds up. The sudden release of the plates causes a .................................. movement and an earthquake occurs. Draw a labelled diagram to explain why earthquakes occur at conservative plate margins. (6 marks)

Are the following statements about continental crust and oceanic crust true or false? (3 marks) Oceanic crust can be destroyed T or F Oceanic crust is generally lighter than continental crust T or F Continental crust is generally older than oceanic crust T or F Give 2 differences between continental and oceanic crust. (2 marks)

3) Explain how volcanoes form at constructive plate margins. (4 marks) 4) Outline how the Richter scale is used to measure earthquakes. (3 marks) 5) What is the difference between the focus and epicentre of an earthquake? (2 marks) 6) Outline the characteristics of a shield volcano (3 marks) 7) Explain the formation of a composite volcano (4 marks)