Chapter 17- Plate Tectonics 8th Grade Science Chapter 17- Plate Tectonics © Fall 2005, Pflugerville ISD, 8th Grade

Chapter 17- Plate Tectonics Section 1: Restless Continents Section 2: The Theory of Plate Tectonics Section 3: Deforming the Earth’s Crust Unit 4 : Chapter 17 : Section 1

Do the Continents Move? What Do You Think? Explain why the following statement is true or false: The state of Texas is moving to the west Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? As the ocean floor spreads, Europe moves east and North America moves west Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? The earth is layered like a chocolate-covered cherry Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? The layers have different properties and different compositions Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? The lithosphere is the cool, outermost layer of the Earth Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? It is divided into huge pieces called tectonic plates, which move on the asthenosphere Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? Asthenosphere is the solid, soft layer of the mantle below the lithosphere Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? Asthenosphere is made of mantle rock that flows slowly, allowing tectonic plates to move on it Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? The mesosphere is the solid lower part of the mantle below the asthenosphere Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? The outer core is the outer shell of Earth’s core. It is made of liquid iron and nickel Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? The inner core is a sphere of solid iron and nickel Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? The core is the solid cherry surrounded by gooey mantle covered with a thin chocolate crust Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? Alfred Wegener, a German scientist, first had the idea that continents can drift around the globe Alfred Wegener 1880-1930 Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? Wegener’s theory of continental drift explained why some land masses fit like puzzle pieces Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? Continental drift also explained why similar fossils are found separated by the oceans Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? Wegener’s theory had the continents plowing through the oceans like this ship plows through ice Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? As is usual with new theories, most scientists didn’t believe in continental drift Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? In the late 1960s, this ship was designed to drill into the ocean floor for core samples Glomar Challenger Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? The core samples revealed that rock at the center of the Atlantic (Red) was younger than rock at the edges (Blue) Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? The process by which new oceanic crust forms at mid-ocean ridges was called seafloor spreading Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? Scientists later discovered that the earth’s magnetic field changes polarity every few thousand years Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? As the rock cools, it records these magnetic reversals in the seafloor Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? With continental fit, seafloor spreading, and magnetic reversals as proof, Wegener’s theory was proved! Alfred Wegener 1880-1930 Unit 4 : Chapter 17 : Section 1

Unit 4 : Chapter 17 : Section 1 Do the Continents Move? With this new theory of Plate Tectonics, Wegener’s idea of a supercontinent was accepted Unit 4 : Chapter 17 : Section 1

The Theory of Plate Tectonics What Do You Think? Consider the amount of energy it would take for humans to pick up a public school and move it a mile. What forces do you think cause the movement of the continents? Unit 4 : Chapter 17 : Section 2

The Theory of Plate Tectonics Unit 4 : Chapter 17 : Section 2

The Theory of Plate Tectonics Unit 4 : Chapter 17 : Section 2

The Theory of Plate Tectonics Unit 4 : Chapter 17 : Section 2

The Theory of Plate Tectonics Unit 4 : Chapter 17 : Section 2

Tectonic Plate Boundaries Where the plates meet, three types of plate boundaries can form… Unit 4 : Chapter 17 : Section 2

Tectonic Plate Boundaries A convergent boundary is where two tectonic plates collide, or run into each other Convergent Boundary Unit 4 : Chapter 17 : Section 2

Convergent Boundaries Unit 4 : Chapter 17 : Section 2

Convergent Boundaries Unit 4 : Chapter 17 : Section 2

Convergent Boundaries Unit 4 : Chapter 17 : Section 2

Tectonic Plate Boundaries A divergent boundary is where two tectonic plates separate from each other Divergent Boundary Unit 4 : Chapter 17 : Section 2

Unit 4 : Chapter 17 : Section 2 Divergent Boundary Unit 4 : Chapter 17 : Section 2

Tectonic Plate Boundaries A transform boundary is where two tectonic plates slide past one another horizontally Transform Boundary Unit 4 : Chapter 17 : Section 2

Unit 4 : Chapter 17 : Section 2 Transform Boundary Unit 4 : Chapter 17 : Section 2

Unit 4 : Chapter 17 : Section 2 Tectonic Settings Scientists use plate tectonics to explain how landforms like mountains and ocean basins form Unit 4 : Chapter 17 : Section 2

Unit 4 : Chapter 17 : Section 2 Tectonic Settings Unit 4 : Chapter 17 : Section 2

Unit 4 : Chapter 17 : Section 2 Tectonic Settings Unit 4 : Chapter 17 : Section 2

Unit 4 : Chapter 17 : Section 2 Tectonic Settings Unit 4 : Chapter 17 : Section 2

Unit 4 : Chapter 17 : Section 2 Tectonic Settings Unit 4 : Chapter 17 : Section 2

Unit 4 : Chapter 17 : Section 3 Deforming the Crust What Do You Think? The Indian Ocean tsunami of 2004 originated at a subduction zone. How did plate tectonics cause these waves that killed over 100,000 people? Unit 4 : Chapter 17 : Section 3

Unit 4 : Chapter 17 : Section 3 Deforming the Crust Unit 4 : Chapter 17 : Section 3

Unit 4 : Chapter 17 : Section 3 Deforming the Crust Unit 4 : Chapter 17 : Section 3

Unit 4 : Chapter 17 : Section 3 Deforming the Crust Stress is the amount of force per unit area that is put on a rock Unit 4 : Chapter 17 : Section 3

Unit 4 : Chapter 17 : Section 3 Deforming the Crust Strain is any change in a rock’s shape caused by stress Unit 4 : Chapter 17 : Section 3

Unit 4 : Chapter 17 : Section 3 Deforming the Crust The deformed strata have been strained by the stress of compression Unit 4 : Chapter 17 : Section 3

Unit 4 : Chapter 17 : Section 3 Deforming the Crust Folding is a type of strain that occurs when rocks bend Unit 4 : Chapter 17 : Section 3

Unit 4 : Chapter 17 : Section 3 Deforming the Crust Faulting is a type of strain that occurs when rock breaks Unit 4 : Chapter 17 : Section 3

Unit 4 : Chapter 17 : Section 3 Building Mountains Almost all mountains are formed at tectonic plate boundaries Mt. Everest, Himalayas Unit 4 : Chapter 17 : Section 3

Building Mountains- Divergent The mid-ocean ridge system is made of two types of mountains: Unit 4 : Chapter 17 : Section 3

Building Mountains- Divergent Fault-block mountains form where the crust is rifting, or separating Unit 4 : Chapter 17 : Section 3

Building Mountains- Divergent Volcanic mountains form outside of the Rift Zone, on either side Unit 4 : Chapter 17 : Section 3

Building Mountains- Convergent At convergent boundaries, either volcanic or folded mountains can form Convergent Boundary Unit 4 : Chapter 17 : Section 2

Building Mountains- Convergent In Alaska, the subduction of the oceanic Pacific plate has created a chain of volcanoes Unit 4 : Chapter 17 : Section 3

Building Mountains- Convergent When ocean was between India and Asia, there were volcanoes Unit 4 : Chapter 17 : Section 3

Building Mountains- Convergent As the continents collide, they create only folded mountains Unit 4 : Chapter 17 : Section 3

Building Mountains- Convergent The Nazca Plate is being subducted beneath the SA Plate Unit 4 : Chapter 17 : Section 3

Building Mountains- Convergent The result is a trench in the ocean and a chain of volcanoes on the continent Unit 4 : Chapter 17 : Section 3

Describe Alfred Wegener’s theory of continental drift. Let’s Review! - 1 - Describe Alfred Wegener’s theory of continental drift. How is this different from the modern theory of plate tectonics? Unit 4 : Chapter 17 : Section 1

What are the three possible driving forces of plate tectonics? Let’s Review! - 2 - What are the three possible driving forces of plate tectonics? Unit 4 : Chapter 17 : Section 2

What kind of mountains would you expect to find near an ocean trench? Let’s Review! - 3 - What kind of mountains would you expect to find near an ocean trench? Unit 4 : Chapter 17 : Section 3

What kinds of mountains would you expect to find at a mid-ocean ridge? Let’s Review! - 4 - What kinds of mountains would you expect to find at a mid-ocean ridge? Unit 4 : Chapter 17 : Section 3

Web Sites to Visit: http://www.scotese.com/ Unit 4 : Chapter 17

Unit 4 : Chapter 17 : Section 1 Pre-AP Extensions Unit 4 : Chapter 17 : Section 1