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The Lithosphere!”The Structure of the Earth & Plate Tectonics. Date: 02/08/12. Lesson Objective ~ • To become familiar with the structure of the Earth • To look at plates •Then volcanoes 1 of 26 © Boardworks Ltd 2003 How old is the Earth? The Earth is… 2 million years old 100 million years old 4600 million years old 30 million years old 2 of 26 © Boardworks Ltd 2003 3 of 26 © Boardworks Ltd 2003 4 of 26 © Boardworks Ltd 2003 Lets look at internet clip and get some data! • Does the data collected, correlate with the information on the handout? If yes/no explain reasons why 5 of 26 © Boardworks Ltd 2003 Cross section of the Earth 6 of 26 © Boardworks Ltd 2003 Write your name and form on the worksheet! 7 of 26 Q: Does this third set of data correlate with the previous two sets of data? Explain with ©examples. Boardworks Ltd 2003 Answers: 1. 2. 3. 4. Trenches Basalt Lithosphere Convection currents 5. Granite 8 of 26 © Boardworks Ltd 2003 Answers: 1. 2. 3. 4. Trenches Basalt Lithosphere Convection currents 5. Granite 9 of 26 © Boardworks Ltd 2003 Lets watch the clip 10 of 26 © Boardworks Ltd 2003 Plate boundaries 11 of 26 © Boardworks Ltd 2003 Continental drift 12 of 26 © Boardworks Ltd 2003 Evidence for plate tectonics 1. Study of fossils – similar fossils are found on different continents. This is evidence that these regions were once very close or joined together. 2. Pattern of rocks – similar pattern of rock layers on different continents is evidence that the rocks were once close together or joined. 3. Shape of continents fit together like a jigsaw. Africa South America 13 of 26 © Boardworks Ltd 2003 Evidence for plate tectonics 4. Magnetic field pattern in iron containing rocks The reversal of the Earth’s magnetic field is recorded in the rocks that solidify at constructive margins. The symmetry around the margin is evidence that the rocks are moving apart. constructive margin SN S S S N N N N S N pattern same both sides 14 of 26 © Boardworks Ltd 2003 15 of 26 © Boardworks Ltd 2003 Why do the plates move? Crust Convention Currents Mantle 16 of 26 © Boardworks Ltd 2003 Eurasian North American Pacific African Plate Nazca South American Indo Australian Plate Antarctic Plate Names 17 of 26 © Boardworks Ltd 2003 AfricanAPlate Indo Australian Plate B Plate Boundaries 18 of 26 Can you name plates A and B? © Boardworks Ltd 2003 Constructive Plate Boundary At a constructive plate boundary, two plates move apart. As the two plates move apart, magma rises up to fill the gap. This causes volcanoes at this type of boundary. However, since the magma can escape easily at the surface the volcano does not erupt with much force. Earthquakes are also found at constructive boundaries. An example of a constructive boundary is the Mid-Atlantic Ridge. 19 of 26 © Boardworks Ltd 2003 Constructive plate boundary 20 of 26 © Boardworks Ltd 2003 Mid-Atlantic ridge Sea Floor Spreading! Did you know that the ocean floor in the Atlantic is growing by 3cm per year? Which of the following pairs of continents are moving further away from each other? 1) Europe and Africa 2) Europe and North America 3) South America and North America 21 of 26 © Boardworks Ltd 2003 Title:_______________________ Put these labels on your diagram: volcanic island / North American plate / Eurasian plate / Volcano / Crust / Mantle In your own words; At a _______plate boundary, two plates move apart. As the two plates move apart, magma rises up to fill the gap. This causes volcanoes at this type of boundary. However, since the magma can escape easily at the surface the volcano does not erupt with much force. Earthquakes are also found at constructive boundaries. An example of a constructive boundary is the Mid-Atlantic Ridge. 22 of 26 © Boardworks Ltd 2003 Title:_______________________ Put these labels on your diagram: volcanic island / North American plate / Eurasian plate / Volcano / Crust / Mantle In your own words; At a _______plate boundary, two plates move apart. As the two plates move apart, magma rises up to fill the gap. This causes volcanoes at this type of boundary. However, since the magma can escape easily at the surface the volcano does not erupt with much force. Earthquakes are also found at constructive boundaries. An example of a constructive boundary is the Mid-Atlantic Ridge. 23 of 26 © Boardworks Ltd 2003 How fast do plates move? The plates move at different rates. The Nazca and Pacific plates are moving apart at a rate of 18cm per year while the Eurasian and North American plates are moving apart at a rate of 3cm per year. To the nearest metre, how far will the Nazca and Pacific plates have moved over the next 200 years? 6 metres 24 of 26 36 metres 200 metres 928 metres © Boardworks Ltd 2003 A destructive plate boundary is found where a continental plate meets an oceanic plate. Destructive Plate Boundary 25 of 26 The oceanic plate descends under the continental plate because it is denser. As the plate descends it starts to melt due to the friction caused by the movement between the plates. This melted plate is now hot, liquid rock (magma). The magma rises through the gaps in the continental plate. If it reaches the surface, the liquid rock forms a volcano. © Boardworks Ltd 2003 26 of 26 © Boardworks Ltd 2003 Title:___________________ Put these labels on your diagram: Andes (fold mountains) / Pacific Ocean / Nazca Plate (Oceanic Crust) / Magma rises / Mantle / Volcanic eruption/ Oceanic crust melts due to friction and heat from the mantle In your own words: ________plate boundary is found where a continental plate meets an oceanic plate. The oceanic plate descends under the continental plate because it is denser. As the plate descends it starts to melt due to the friction caused by the movement between the plates. This melted plate is now hot, liquid rock (magma). The magma rises through the gaps in the continental plate. If it reaches the surface, the liquid rock forms a volcano. 27 of 26 © Boardworks Ltd 2003 Title:___________________ Put these labels on your diagram: Andes (fold mountains) / Pacific Ocean / Nazca Plate (Oceanic Crust) / Magma rises / Mantle / Volcanic eruption/ Oceanic crust melts due to friction and heat from the mantle In your own words:________ plate boundary is found where a continental plate meets an oceanic plate. The oceanic plate descends under the continental plate because it is denser. As the plate descends it starts to melt due to the friction caused by the movement between the plates. This melted plate is now hot, liquid rock (magma). The magma rises through the gaps in the continental plate. If it reaches the surface, the liquid rock forms a volcano. 28 of 26 © Boardworks Ltd 2003 Collision Boundary 29 of 26 Collision boundaries occur when 2 plates of similar densities move together (i.e. a continental plate and a continental plate). This causes the material between them to buckle and rise up, forming fold mountains. The Himalayas are an example of a chain of fold mountains. They have been formed by the African plate colliding into the Eurasian plate. © Boardworks Ltd 2003 30 of 26 © Boardworks Ltd 2003 Title:_________________________ Put these labels on your diagram: collision zone / mantle / Himalayas / Eurasian plate. Collision margins / Constructive margins In your own words: _________ boundaries occur when 2 plates of similar densities move together (i.e. a continental plate and a continental plate). This causes the material between them to buckle and rise up, forming fold mountains. The Himalayas are an example of a chain of fold mountains. They have been formed by the African plate colliding into the Eurasian plate. 31 of 26 © Boardworks Ltd 2003 Title:_________________________ Put these labels on your diagram: collision zone / mantle / Himalayas / Eurasian plate. Collision margins / Constructive margins In your own words: _________ boundaries occur when 2 plates of similar densities move together (i.e. a continental plate and a continental plate). This causes the material between them to buckle and rise up, forming fold mountains. The Himalayas are an example of a chain of fold mountains. They have been formed by the African plate colliding into the Eurasian plate. 32 of 26 © Boardworks Ltd 2003 Conservative plate boundaries exist where two plates do not directly collide but slide past each other along a fault (weakness). Conservative Boundary No volcanoes are found along these plate boundaries, but earthquakes do occur. An example of such a boundary is the San Andreas Fault in California. 33 of 26 © Boardworks Ltd 2003 34 of 26 © Boardworks Ltd 2003 Title:_______________________ In your own words: _________ plate boundaries exist where two plates do not directly collide but slide past each other along a fault (weakness). No volcanoes are found along these plate boundaries, but earthquakes do occur. An example of such a boundary is the San Andreas Fault in California. Fill in the blanks, two plates, a country name and 3 places, S___D____, L__ A______ & S_____________, ocean. 35 of 26 © Boardworks Ltd 2003 36 of 26 © Boardworks Ltd 2003 Let’s shake and bake!!! • In your groups quietly decide which one of the four plates you are going to act out, remember try and act out as many features and process of your chosen plate. • Can you guess which “plate” your fellow classmates are?? Ask them where they may find this plate on planet earth or any other question. 37 of 26 © Boardworks Ltd 2003 Homework, due in st Thursday/Friday20/21 of October. 38 of 26 © Boardworks Ltd 2003 Attach labels to the correct part of the diagram. Outer core Crust Mantle Inner core 39 of 26 © Boardworks Ltd 2003 Name this plate boundary A G B E C F D Match the labels to the letters Earthquakes occur due to friction The oceanic crust sinks under the less dense continental crust Oceanic plate Continental crust 40 of 26 Explosive volcanoes The oceanic crust melts and rises Mantle © Boardworks Ltd 2003 Constructive plate boundaries MID OCEAN RIDGE B A Ocean Mantle Where would you find older rocks – at A or at B? 41 of 26 © Boardworks Ltd 2003 42 of 26 © Boardworks Ltd 2003 Mark the following events on your time line. What do you notice? India collides with Asia – 50 m First flowers appear – 100 m Man (homo sapiens) inhabits the Earth – 0.1 m Formation of the Alps – 30 m Dinosaur extinction – 65 m You were born! – 0.00013 m Industrial Revolution (UK) - 0.0001 m (figures are in ‘millions of years ago’) 43 of 26 © Boardworks Ltd 2003