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Chapter 10 Plate Tectonics Table of Contents Section 1 Continental Drift Section 2 The Theory of Plate Tectonics Section 3 The Changing Continents Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Continental Drift Wegener’s Hypothesis • Continental drift the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present location – Proposed by Alfred Wegener in 1912. – Fossil Evidence: fossils of the same plants and animals could be found in areas of continents that had once been connected. – Evidence from Rock Formations: ages and types of rocks in the coastal regions of widely separated areas matched closely. – Climatic Evidence: changes in climatic patterns suggested the continents had not always been located where they are now. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Continental Drift Wegener’s Hypothesis, continued • Similar rock formations and fossil evidence supported Wegener’s hypothesis. 1. mid-ocean ridges 2. Sea-floor spreading 3. paleomagn etism Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Continental Drift 1. Mid-Ocean Ridges • long, undersea mountain chain • steep, narrow valley at its center • forms as magma rises from the asthenosphere • creates new oceanic lithosphere (sea floor) as tectonic plates move apart • Rocks closer to Mid-ocean ridges – Younger – Less sedimented Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Continental Drift 2. Sea-Floor Spreading • Sea-floor spreading – The force of magma (molten rock) pushing up through cracks in the ocean crust along the mid-ocean ridges – As the ocean floor spreads apart, magma rises to fill the rift and then cools to form new rock. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Continental Drift Sea-Floor Spreading, continued Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Continental Drift Sea-Floor Spreading, continued Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Continental Drift 3. Paleomagnetism – the study of the alignment of magnetic minerals in rock Magnetic Reversals: The earth generates a magnetic field – • cooling magma with iron align themselves with the poles, much like a compass needle • Earth's magnetic field is unstable and will flip every so often (hundreds of thousands to million of years). • Magnetic lineation on the sea floor, nearly identical patterns on either side of ridge Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Continental Drift Paleomagnetism, continued Magnetic Symmetry • magnetic pattern on one side of a mid-ocean ridge is a mirror image to the other side. • indicate that new rock forms at the center of a ridge and then move away from the center in opposite directions. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Continental Drift Continental Drift (Pangaea) Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics Objectives • Summarize the theory of plate tectonics. • Identify and describe the three types of plate boundaries. • List and describe three causes of plate movement. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics How Continents Move • plate tectonics the theory that explains how large pieces of the lithospehere, called plates, move and change shape – lithosphere the solid, outer layer of Earth that consists of the crust and the rigid upper part of the mantle • tectonic plates – include continental crust, oceanic crust, or both – Continents and oceans are carried along on the moving tectonic plates – About 15 tectonic plates Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics Tectonic Plates – asthenosphere the solid, plastic layer of the mantle beneath the lithosphere • made of mantle rock that flows very slowly • which allows tectonic plates to move on top of it Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics Tectonic Plates, continued The boundaries of tectonic plates do not always match the outlines of continents. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics 3 Types of Plate Boundaries • divergent boundaries • convergent boundaries • transform boundaries. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics Types of Plate Boundaries, continued The boundary between • insert TTthat are tectonic plates moving away from each other Forms: • Rifts • mid-ocean ridges Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics Types of Plate Boundaries, continued •Theinsert TT between boundary tectonic plates that are colliding Forms: • ocean trenches •Mountain ranges •Volcanoes •Island arcs Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics Types of Plate Boundaries, continued • insert TT The boundary between tectonic plates that are sliding one another Earthquakes Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics Causes of Plate Motion • Convection – is the movement of heated material due to differences in density that are caused by differences in temperatures. • Convection cell. – A cycle created by the cooler, denser water sinks, and the warmer water rises to the surface. • Mantle Convection – As the mantle material moves, it drags the overlying tectonic plates along with it. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics 2 types of plate motion 1. Ridge Push As the cooling lithosphere sinks, asthenosphere moves away and pushes on the bottom of the plate. • Insert TT Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics 2 types of plate motion 2. Slab Pull • Insert TT Cooled lithosphere becomes dense and sinks under (subduct into) asthenosphere in a process called slab pull Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 The Theory of Plate Tectonics Plate Tectonics Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents Objectives • Identify how movements of tectonic plates change Earth’s surface. • Summarize how movements of tectonic plates have influenced climates and life on Earth. • Describe the supercontinent cycle. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents Reshaping Earth’s Crust 1. rifting – the process by which Earth’s crust breaks apart – Heat from mantle builds up lithosphere becomes thinner – Cratons • stable rock contained in continents • older than 540 million years. – Sheilds – rocks within craton, exposed to earth’s surface Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents Reshaping Earth’s Crust, continued 2. Continental Growth • terrane – a piece of lithosphere that has a unique geologic history – Terranes become part of a continent at convergent boundaries • Subducts under a lithosphere • Terrane is scraped off of the subducting plate – part of the continent • Look at figure 2 on pg 256 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents Effects of Continental Change 1. Climates – When continents move, the flow of air and moisture around the globe changes and causes climates to change. – Ice melts as continents move around 2. Change in life – populations of organisms are separated. – populations are separated, new species may evolve Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents The Supercontinent Cycle • supercontinent cycle the process by which supercontinents form and break apart over millions of years • Pangaea – the supercontinent that formed 300 million years – began to break up beginning 250 million years ago Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents The Supercontinent Cycle, continued 1. Formation of pangea • Mountain ranges were formed • Panthalassa – the single, large ocean during Pangaea • Tethys Sea – cut into the eastern edge of Pangaea. 2. Breakup of Pangaea • About 250 million years ago Paleozoic Era • Broke into Laurasia and Gondwanaland. • Laurasia = North America and Eurasia. • Gondwanaland = Africa, South America, India, Australia, and Antarctica. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 The Supercontinent Cycle Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents The Supercontinent Cycle, continued Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents The Supercontinent Cycle, continued Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents The Supercontinent Cycle, continued Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents The Supercontinent Cycle, continued Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. In the future, 1. In about 150million years, African will collide with Eurasia 2. Australia will also eventually collide with Eurasia 3. In about 250million years, a new supercontinent will form Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents The Supercontinent Cycle, continued Reading Check What modern continents formed from Gondwanaland? Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents The Supercontinent Cycle, continued Reading Check Answer What modern continents formed from Gondwanaland? The continents Africa, South America, Antarctica, and Australia formed from Gondwanaland. The subcontinent of India was also part of Gondwanaland. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 The Changing Continents The Supercontinent Cycle, continued Geography of the Future • As tectonic plates continue to move, Earth’s geography will change dramatically. • Scientists predict that in 250 million years, the continents will come together again to form a new supercontinent. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Maps in Action Maps in Action Locations of Earthquakes in South America, 2002–2003 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Movements of the Ocean Brain Food Video Quiz Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Multiple Choice 1. Which of the following factors is most important when determining the type of collision that forms when two lithospheric plates collide? A. the density of each plate B. the size of each plate C. the paleomagnetism of the rock D. the length of the boundary Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Multiple Choice, continued 1. Which of the following factors is most important when determining the type of collision that forms when two lithospheric plates collide? A. the density of each plate B. the size of each plate C. the paleomagnetism of the rock D. the length of the boundary Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Multiple Choice, continued 2. At locations where sea-floor occurs, rock is moved away from a mid-ocean ridge. What replaces the rock as it moves away? F. G. H. I. molten rock older rock continental crust compacted sediment Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Multiple Choice, continued 2. At locations where sea-floor occurs, rock is moved away from a mid-ocean ridge. What replaces the rock as it moves away? F. G. H. I. molten rock older rock continental crust compacted sediment Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Multiple Choice, continued 3. Which of the following was a weakness of Wegener’s proposal of continental drift when he first proposed the hypothesis? A. an absence of fossil evidence B. unsupported climatic evidence C. unrelated continent features D. a lack of proven mechanisms Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Multiple Choice, continued 3. Which of the following was a weakness of Wegener’s proposal of continental drift when he first proposed the hypothesis? A. an absence of fossil evidence B. unsupported climatic evidence C. unrelated continent features D. a lack of proven mechanisms Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Multiple Choice, continued 4. Which of the following statements describes a specific type of continental growth? F. Continents change not only by gaining material but also by losing material. G. Terranes become part of a continent at convergent boundaries. H. Ocean sediments move onto land because of sea-floor spreading. I. Rifting adds new rock to a continent and causes the continent to become wider. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Multiple Choice, continued 4. Which of the following statements describes a specific type of continental growth? F. Continents change not only by gaining material but also by losing material. G. Terranes become part of a continent at convergent boundaries. H. Ocean sediments move onto land because of sea-floor spreading. I. Rifting adds new rock to a continent and causes the continent to become wider. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Short Response 5. What is the name for the process by which the Earth’s crust breaks apart? Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Short Response, continued 5. What is the name for the process by which the Earth’s crust breaks apart? rifting Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Short Response, continued 6. What is the name for the layer of plastic rock directly below the lithosphere? Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Short Response, continued 6. What is the name for the layer of plastic rock directly below the lithosphere? the asthenosphere Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Reading Skills Read the passage below. Then, answer questions 7–9. The Himalaya Mountains The Himalaya Mountains are a range of mountains that is 2,400 km long and that arcs across Pakistan, India, Tibet, Nepal, Sikkim, and Bhutan. The Himalaya Mountains are the highest mountains on Earth. Nine mountains in the chain, including Mount Everest, the tallest above-water mountain on Earth, rise to heights of more than 8,000 m above sea-level. Mount Everest stands 8,850 m tall. The formation of the Himalaya Mountains began about 80 million years ago. A tectonic plate carrying the Indian subcontinent collided with the Eurasian plate. The Indian plate was denser than the Eurasian plate. This difference in density caused the uplifting of the Eurasian plate and the subsequent formation of the Himalaya Mountains. This process continues today. The Indian plate continues to push under the Eurasian plate. New measurements show that Mount Everest is moving to the northeast by as much as 10 cm per year. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Reading Skills, continued 7. According to the passage, what geologic process formed the Himalaya Mountains? A. divergence B. continental drift C. strike-slip faulting D. convergence Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Reading Skills, continued 7. According to the passage, what geologic process formed the Himalaya Mountains? A. divergence B. continental drift C. strike-slip faulting D. convergence Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Reading Skills, continued 8. Which of the following statements is a fact according to the passage? F. The nine tallest mountains on Earth are located in the Himalaya Mountains. G. The Himalaya Mountains are the longest mountain chain on Earth. H. The Himalaya Mountains are located within six countries. I. The Himalaya Mountains had completely formed by 80 million years ago. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Reading Skills, continued 8. Which of the following statements is a fact according to the passage? F. The nine tallest mountains on Earth are located in the Himalaya Mountains. G. The Himalaya Mountains are the longest mountain chain on Earth. H. The Himalaya Mountains are located within six countries. I. The Himalaya Mountains had completely formed by 80 million years ago. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Reading Skills, continued 9. Which plate is being subducted along the fault that formed the Himalaya Mountains? A. The Indian plate is being subducted. B. The Eurasian plate is being subducted. C. Both plates are being equally subducted. D. Neither plate is being subducted. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Reading Skills, continued 9. Which plate is being subducted along the fault that formed the Himalaya Mountains? A. The Indian plate is being subducted. B. The Eurasian plate is being subducted. C. Both plates are being equally subducted. D. Neither plate is being subducted. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Interpreting Graphics Use the map below to answer questions 10 and 11. The map shows the locations of the Earth’s major tectonic plate boundaries. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Interpreting Graphics, continued 10. What type of boundary is found between the South American plate and the African Plate? A. B. C. D. convergent divergent transform subduction Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Interpreting Graphics, continued 10. What type of boundary is found between the South American plate and the African Plate? A. B. C. D. convergent divergent transform subduction Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Interpreting Graphics, continued 11. What type of boundary is found between the South American plate and the African plate? What surface features are most often at boundaries of this type? Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Interpreting Graphics, continued 11. What type of boundary is found between the South American plate and the African plate? What surface features are most often at boundaries of this type? Answers should include: the boundary between the South American plate and the African plate is a divergent boundary; most divergent boundaries are located on the ocean floor and produce mid-ocean ridges and underwater mountain ranges Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Interpreting Graphics, continued Use the graphic below to answer questions 12 and 13. The graphic shows a strike-slip fault along a transform boundary. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Interpreting Graphics, continued 12. What type of crustal interaction is indicated by the letter E? F. G. H. I. continental rifting sea-floor spreading divergence subduction Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Interpreting Graphics, continued 12. What type of crustal interaction is indicated by the letter E? F. G. H. I. continental rifting sea-floor spreading divergence subduction Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Interpreting Graphics, continued 13. Describe how a transform boundary differs from the boundaries shown by letters D and E in terms of plate movement and magmatic activity. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Prep Interpreting Graphics, continued 13. Describe how a transform boundary differs from the boundaries shown by letters D and E in terms of plate movement and magmatic activity. Answers should include: unlike the plates at a convergent boundary, shown by letter E, or divergent boundary, shown by letter D, plates at a transform boundary move past one another, not into or away from one another; transform boundaries produce a number of earthquakes, but they do not produce magma or cause mountain formation Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Tectonic Plates Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Types of Plate Boundaries Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Ridge Push and Slab Pull Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Locations of Earthquakes in South America, 2002-2003 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.