Chapter 7 Table of Contents Section 1 Inside the Earth Plate Tectonics Table of Contents Section 1 Inside the Earth Section 2 Restless Continents Section 3 The Theory of Plate Tectonics Section 4 Deforming the Earth’s Crust

Chapter 7: Plate Tectonics

Chapter 7 Section 1 Inside the Earth Bellringer If you journeyed to the center of the Earth, what do you think you would observe along the way?   Draw an illustration of the journey in your science journal.

Science Question of the Day 1/24/11 Chapter 7 Section 1 Inside the Earth Science Question of the Day 1/24/11 A: The cell  

Chapter 7 Section 1 Inside the Earth Review 11/22/11 Put the 5 physical layers of the Earth in order from outside to inside. What is the difference between elements found at the surface of the Earth and elements found inside the Earth? What are tectonic plates? How can tectonic plates move and shift? Describe the asthenosphere. How did scientists determine that the Earth was composed of different layers if they can’t see the inside of the Earth?

Journal 11/28/12 Chapter 7 What are tectonic plates? Section 1 Inside the Earth Journal 11/28/12 What are tectonic plates? What do they mean when they say the mantle is plastic-like?

Chapter 7 Section 1 Inside the Earth Journal 11/30/12 What causes these balloons to rise into the air?

Chapter 7 Section 1 Inside the Earth Journal 11/27/12 If you compared the Earth with an apple the skin would be like what layer of the Earth? Most of the mass of the Earth is found in what layer? This layer of the Earth is mostly made of dense elements such as iron.

Journal 12/3/12 Chapter 7 What is an observation? Section 1 Inside the Earth Journal 12/3/12 What is an observation? What is an inference? What is the amount of matter in an object? What is the space an object takes up? What is the amount of matter in an object divided by the amount of space it takes up?

Journal 12/4/12 Chapter 7 What is a tectonic plate? Section 1 Inside the Earth Journal 12/4/12 What is a tectonic plate? What is a tectonic plate boundary? What are the three types of tectonic plate boundaries?

Journal 12/6/12 Ch 7 Exam Tomorrow! Chapter 7 Section 1 Inside the Earth Journal 12/6/12 Ch 7 Exam Tomorrow! Make a hypothesis as to what will happen to the food coloring after I place a candle under the jar. What is convection and how does it contribute to the movement of the tectonic plates? Describe what will happen during a continental-continental collision, an oceanic-oceanic collision, and a continental-oceanic collision. Draw a monocline, syncline, and anticline.

Chapter 7 Section 1 Inside the Earth Objectives Identify the layers of the Earth by their chemical composition. Identify the layers of the Earth by their physical properties. Describe a tectonic plate. Explain how scientists know about the structure of Earth’s interior.

The Composition of the Earth Chapter 7 Section 1 Inside the Earth The Composition of the Earth The Earth is divided into three layers—the crust, the mantle, and the core—based on the compounds that make up each layer. The Crust is the outermost layer of the Earth. The crust is 5 to 100 km thick, and is the thinnest layer of the Earth.

The Composition of the Earth, continued Chapter 7 Section 1 Inside the Earth The Composition of the Earth, continued There are two types of crust—continental and oceanic. Oceanic crust is thinner and denser than continental crust.

The Composition of the Earth, continued Chapter 7 Section 1 Inside the Earth The Composition of the Earth, continued The Mantle is the layer of the Earth between the crust and the core. The mantle is much thicker than the crust and contains most of the Earth’s mass. The crust is too thick to drill through, so scientists must draw conclusions about the composition and other properties of the mantle from observations made on the Earth’s surface.

The Composition of the Earth, continued Chapter 7 Section 1 Inside the Earth The Composition of the Earth, continued The Core is the central part of the Earth that lies below the mantle. The core makes up about one-third of Earth’s mass. Scientists think that the Earth’s core is made mostly of iron and contains smaller amounts of nickel but almost no oxygen, silicon, aluminum, or magnesium.

Chapter 7 Section 1 Inside the Earth

The Physical Structure of the Earth Chapter 7 Section 1 Inside the Earth The Physical Structure of the Earth The Earth is divided into five physical layers: The lithosphere The asthenosphere The mesosphere The outer core The inner core Each layer has its own set of physical properties.

Physical Structure of the Earth, continued Chapter 7 Section 1 Inside the Earth Physical Structure of the Earth, continued The outermost, rigid layer of the Earth is called the lithosphere. The lithosphere is made of two parts—the crust and the rigid upper part of the mantle. The lithosphere is divided into pieces that are called tectonic plates.

Physical Structure of the Earth, continued Chapter 7 Section 1 Inside the Earth Physical Structure of the Earth, continued The asthenosphere is a plastic layer of the mantle on which the tectonic plates move. The asthenosphere is made of solid rock that flows very slowly.

Chapter 7 Section 1 Inside the Earth

Physical Structure of the Earth, continued Chapter 7 Section 1 Inside the Earth1 Physical Structure of the Earth, continued The mesosphere is the strong, lower part of the mantle between the asthenosphere and the outer core. The prefix meso- means “middle.”

Physical Structure of the Earth, continued Chapter 7 Section 1 Inside the Earth Physical Structure of the Earth, continued The Earth’s core is divided into two parts. The outer core is the liquid layer of the Earth’s core that lies beneath the mantle. The inner core is the solid, dense center of our planet that extends from the bottom of the outer core to the center of the Earth, about 6,380 km beneath the surface.

Chapter 7 Section 1 Inside the Earth

Tectonic Plates Chapter 7 Section 1 Inside the Earth Tectonic Plates Pieces of the lithosphere that move around on top of the asthenosphere are called tectonic plates. Tectonic plates consist of the crust and the rigid, outermost part of the mantle.

Tectonic Plates, continued Chapter 7 Section 1 Inside the Earth Tectonic Plates, continued A Giant Jigsaw Puzzle Each tectonic plate fits together with the tectonic plates that surround it. The lithosphere is like a jigsaw puzzle. The tectonic plates are like the pieces of the puzzle.

Tectonic Plates, continued Chapter 7 Section 1 Inside the Earth Tectonic Plates, continued A Tectonic Plate Close-Up The following Visual Concept presentation shows the Earth’s major tectonic plates and how they fit together. The presentation also illustrates what a tectonic plate might look like if you could lift it out of its place.

Tectonic Plates Chapter 7 Section 1 Inside the Earth Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

Tectonic Plates, continued Chapter 7 Section 1 Inside the Earth Tectonic Plates, continued Tectonic plates “float” on the asthenosphere. The plates cover the surface of the asthenosphere, and they touch one another and move around. The lithosphere displaces the asthenosphere. Thick tectonic plates, such as those made of continental crust, displace more asthenosphere than do thin plates, such as those made of oceanic lithosphere.

Mapping the Earth’s Interior Chapter 7 Section 1 Inside the Earth Mapping the Earth’s Interior Scientists have learned much about the deepest parts of the planet by measuring the speeds of the seismic waves that travel through the Earth’s interior during earthquakes. By using seismographs, scientists have learned that the Earth is made of different layers.

Seismographs and Mapping Earth’s Layers Chapter 7 Section 1 Inside the Earth Seismographs and Mapping Earth’s Layers Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

Chapter 7 Section 2 Restless Continents Bellringer What is meant by the statement: “The United States is moving westward”? From what you know about geology and plate tectonics, explain if you believe this statement to be true or false.

Chapter 7 Section 1 Inside the Earth Science Question of the Day 1/26/11 Word Bank: Cell, Cell membrane, Organelles, Cell wall, Structure, Organ, Prokaryote, Eukaryote, Tissue, Function, Mitochondria A(n) ____ is the most basic unit of all living things. The ___ produces the energy for the cell by breaking down sugar. Ribosomes and Mitochondria are types of ___. A(n) ____ is an organism whose cells have a nucleus. A group of cells working together to perform a specific function is a ___. Only plant cells have a ___.  

Chapter 7 Section 1 Inside the Earth Quiz 11/23/11 Name the 5 physical layers of the Earth from outside to inside. Describe the asthenosphere. What does the prefix “meso” mean? The elements at the center of the Earth are more ________ than elements at the surface.  

Chapter 7 Section 2 Restless Continents Objectives Describe Wegener’s hypothesis of continental drift. Explain how sea-floor spreading provides a way for continents to move. Describe how new oceanic lithosphere forms at mid-ocean ridges. Explain how magnetic reversals provide evidence for sea-floor spreading.

Wegener’s Continental Drift Hypothesis Chapter 7 Section 2 Restless Continents Wegener’s Continental Drift Hypothesis Continental drift is the hypothesis that states that continents once formed a single landmass, broke up, and drifted to their present locations. Scientist Alfred Wegener developed the hypothesis in the early 1900s.

The Breakup of Pangaea Chapter 7 Section 2 Restless Continents The Breakup of Pangaea Wegener theorized that all of the present continents were once joined in a single, huge continent he called Pangaea. Pangaea is Greek for “all earth.” Pangaea existed about 245 million years ago.

Continental Drift Chapter 7 Section 2 Restless Continents Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

Sea-Floor Spreading Chapter 7 Section 2 Restless Continents Sea-Floor Spreading Evidence to support the continental drift hypothesis comes from sea-floor spreading. Sea-floor spreading is the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies.

Sea-Floor Spreading, continued Chapter 7 Section 2 Restless Continents Sea-Floor Spreading, continued Mid-Ocean Ridges and Sea-Floor Spreading Mid-ocean ridges are underwater mountain chains that run through Earth’s ocean basins. These mid-ocean ridges are the places where sea-floor spreading takes place.

Chapter 7 Section 2 Restless Continents

Sea-Floor Spreading, continued Chapter 7 Section 2 Restless Continents Sea-Floor Spreading, continued Evidence for Sea-Floor Spreading: Magnetic Reversals Some of the most important evidence of sea-floor spreading comes from magnetic reversals recorded in the ocean floor. Throughout Earth’s history, the north and south magnetic poles have changed places many times.

Sea-Floor Spreading, continued Chapter 7 Section 2 Restless Continents Sea-Floor Spreading, continued Magnetic Reversals and Sea-Floor Spreading Molten rock at the mid-ocean ridge contains tiny grains of magnetic minerals that act like compasses. These minerals align with the magnetic field of the Earth. When the molten rock cools, the record of these tiny compasses remains in the rock.

Sea-Floor Spreading, continued Chapter 7 Section 2 Restless Continents Sea-Floor Spreading, continued When the Earth’s magnetic field reverses, the magnetic mineral grains align in the opposite direction. The new rock records the direction of the Earth’s magnetic field. As the sea floor spreads away from a mid-ocean ridge, it carries with it a record of these magnetic reversals.

Sea-Floor Spreading, continued Chapter 7 Section 2 Restless Continents Sea-Floor Spreading, continued

Chapter 7 Magnetic Reversals and Sea-Floor Spreading Section 2 Restless Continents Magnetic Reversals and Sea-Floor Spreading Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

Quiz 11/28/11 Chapter 7 Explain what causes tectonic plate movement. Section 2 Restless Continents Quiz 11/28/11 Explain what causes tectonic plate movement. How does magnetic reversals of the earth provide evidence that the sea floor is spreading? What is a mid-ocean ridge?

Chapter 7 Section 3 The Theory of Plate Tectonics Bellringer If the sea floor is spreading an average of 4 cm a year, how many years did it take New York and the northwest coast of Africa to reach their current locations, 676,000,000 cm apart?

Chapter 7 MCA Review Science Question of the Day 1/28/11  

Chapter 7 Section 3 The Theory of Plate Tectonics Objectives Describe the three types of tectonic plate boundaries. Describe the three forces thought to move tectonic plates. Explain how scientists measure the rate at which tectonic plates move.

Tectonic Plate Boundaries Chapter 7 Section 3 The Theory of Plate Tectonics Tectonic Plate Boundaries As scientists’ understanding of mid-ocean ridges and magnetic reversals grew, a theory was formed to explain how tectonic plates move. Plate tectonics is the theory that explains how large pieces of the Earth’s outermost layer, called tectonic plates, move and change shape.

Tectonic Plate Boundaries, continued Chapter 7 Section 3 The Theory of Plate Tectonics Tectonic Plate Boundaries, continued A boundary is a place where tectonic plates touch. All tectonic plates share boundaries with other tectonic plates. The type of boundary depends on how the tectonic plates move relative to one another.

Tectonic Plate Boundaries, continued Chapter 7 Section 3 The Theory of Plate Tectonics Tectonic Plate Boundaries, continued There are three types of tectonic plate boundaries: Convergent Boundaries Divergent Boundaries Transform Boundaries

Tectonic Plate Boundaries, continued Chapter 7 Section 3 The Theory of Plate Tectonics Tectonic Plate Boundaries, continued When two tectonic plates collide, the boundary between them is a convergent boundary. What happens at convergent boundaries depends on the kind of crust at the leading edge of each tectonic plate.

Chapter 7 Section 3 The Theory of Plate Tectonics

Tectonic Plate Boundaries Chapter 7 Section 3 The Theory of Plate Tectonics Tectonic Plate Boundaries Click below to watch the Visual Concept. Visual Concept Visual Concept

Tectonic Plate Boundaries, continued Chapter 7 Section 3 The Theory of Plate Tectonics Tectonic Plate Boundaries, continued When two tectonic plates separate, the boundary between them is called a divergent boundary. New sea floor forms at divergent boundaries.

Tectonic Plate Boundaries, continued Chapter 7 Section 3 The Theory of Plate Tectonics Tectonic Plate Boundaries, continued When two tectonic plates slide past each other horizontally, the boundary between is called a transform boundary. The San Andreas Fault in California is an example of a transform boundary.

Chapter 7 Section 3 The Theory of Plate Tectonics

Possible Causes of Tectonic Plate Motion Chapter 7 Section 3 The Theory of Plate Tectonics Possible Causes of Tectonic Plate Motion Tectonic plate movement occurs because of changes in the density within the asthenosphere. The following Visual Concept presentation examines three possible driving forces of tectonic plate motion.

Causes of Tectonic Plate Motion Chapter 7 Section 3 The Theory of Plate Tectonics Causes of Tectonic Plate Motion Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

Tracking Tectonic Plate Motion Chapter 7 Section 3 The Theory of Plate Tectonics Tracking Tectonic Plate Motion Tectonic plate movements are so slow and gradual that you can’t see or feel them. The movement is measured in centimeters per year. Scientists use a system of satellites called the global positioning system (GPS) to measure the rate of tectonic plate movement.

Tracking Tectonic Plate Motion, continued Chapter 7 Section 3 The Theory of Plate Tectonics Tracking Tectonic Plate Motion, continued Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

Chapter 7 Section 4 Deforming the Earth’s Crust Bellringer Compare the mountains in the photographs. Write a description of each mountain, and suggest how it might have formed. Do you know where these various types of mountains are found in the world? Have you ever visited any of them? Would it ever be dangerous to study them?

Chapter 7 MCA Review Science Question of the Day 1/26/11 Word Bank: Cell, Cell membrane, Organelles, Cell wall, Structure, Organ, Prokaryote, Eukaryote, Tissue, Function, Mitochondria A(n) ____ is the most basic unit of all living things. The ___ produces the energy for the cell by breaking down sugar. Ribosomes and Mitochondria are types of ___. A(n) ____ is an organism whose cells have a nucleus. A group of cells working together to perform a specific function is a ___. Only plant cells have a ___.  

Objectives Chapter 7 Describe two types of stress that deform rocks. Section 4 Deforming the Earth’s Crust Objectives Describe two types of stress that deform rocks. Describe three major types of folds. Explain the differences between the three major types of faults. Identify the most common types of mountains. Explain the difference between uplift and subsidence.

Chapter 7 Section 4 Deforming the Earth’s Crust Deformation Whether a material bends or breaks depends on the how much stress is applied to the material. Stress is the amount of force per unit area on a given material. Different things happen to rock when different types of stress are applied.

Deformation, continued Chapter 7 Section 4 Deforming the Earth’s Crust Deformation, continued The process by which the shape of a rock changes because of stress is called deformation. Rock layers bend when stress is placed on them. When enough stress is placed on rocks, they can reach their elastic limit and break.

Deformation, continued Chapter 7 Section 4 Deforming the Earth’s Crust Deformation, continued The type of stress that occurs when an object is squeezed, such as when two tectonic plates collide, is called compression. When compression occurs at a convergent boundary, large mountain ranges can form.

Deformation, continued Chapter 7 Section 4 Deforming the Earth’s Crust Deformation, continued Tension is stress that occurs when forces act to stretch an object. Tension occurs at divergent plate boundaries, such as mid-ocean ridges, when two tectonic plates pull away from each other.

Chapter 7 Section 4 Deforming the Earth’s Crust Folding The bending of rock layers because of stress in the Earth’s crust is called folding. Types of Folds Depending on how rock layers deform, different types of folds are made. The major types of folds are anticlines, synclines, and monoclines.

Folding, continued Chapter 7 Anticlines are upward-arching folds. Section 4 Deforming the Earth’s Crust Folding, continued Anticlines are upward-arching folds. Synclines are downward, troughlike folds.

Folding, continued Chapter 7 Section 4 Deforming the Earth’s Crust Folding, continued In a monocline, rock layers are folded so that both ends of the fold are horizontal.

Chapter 7 Section 4 Deforming the Earth’s Crust Faulting Some rock layers break when stress is applied. The surface along which rocks break and slide past each other is called a fault. The blocks of crust on each side of the fault are called fault blocks.

Faulting, continued Chapter 7 Section 4 Deforming the Earth’s Crust Faulting, continued When a fault is not vertical, its two sides are either a hanging wall or a footwall.

Faulting, continued Chapter 7 Section 4 Deforming the Earth’s Crust Faulting, continued The type of fault depends on how the hanging wall and footwall move in relationship to each other. When a normal fault moves, it causes the hanging wall to move down relative to the footwall.

Faulting, continued Chapter 7 Section 4 Deforming the Earth’s Crust Faulting, continued When a reverse fault moves, it causes the hanging wall to move up relative to the footwall.

Faulting, continued Chapter 7 Section 4 Deforming the Earth’s Crust Faulting, continued A third major type of fault is a strike-slip fault. These faults form when opposing forces cause rock to break and move horizontally.

Plate Tectonics and Mountain Building Chapter 7 Section 4 Deforming the Earth’s Crust Plate Tectonics and Mountain Building When tectonic plates collide, land features that start as folds and faults can eventually become large mountain ranges. When tectonic plates undergo compressions or tension, they can form mountains in several ways.

Mountain Building, continued Chapter 7 Section 4 Deforming the Earth’s Crust Mountain Building, continued Folded Mountains form when rock layers are squeezed together and pushed upward. Fault-Block Mountains form when large blocks of the Earth’s crust drop down relative to other blocks. Volcanic Mountains form when magma rises to the Earth’s surface and erupts.

Uplift and Subsidence Chapter 7 Section 4 Deforming the Earth’s Crust Uplift and Subsidence Vertical movements in the crust are divided into two types—uplift and subsidence. Uplift is the rising of regions of the Earth’s crust to higher elevations. Subsidence is the sinking of regions of the Earth’s crust to lower elevations.

Uplift and Subsidence, continued Chapter 7 Section 4 Deforming the Earth’s Crust Uplift and Subsidence, continued Uplifting of Depressed Rocks Uplift can occur when large areas of land rise without deforming. One way areas rise without deforming is process known as rebound. When the crust rebounds, it slowly springs back to its previous elevation.

Uplift and Subsidence, continued Chapter 7 Section 4 Deforming the Earth’s Crust Uplift and Subsidence, continued Subsidence of Cooler Rocks Rocks that are hot take up more space than cooler rocks. The lithosphere is relatively hot at mid-ocean ridges, but cools as it moves farther from the ridge. As it cools, the oceanic lithosphere takes up less volume and the ocean floor subsides.

Uplift and Subsidence, continued Chapter 7 Section 4 Deforming the Earth’s Crust Uplift and Subsidence, continued Tectonic Letdown Subsidence can also occur when the lithosphere becomes stretched in rift zones. A rift zone is a set of deep cracks that forms between two tectonic plates that are pulling away from each other. As tectonic plates pull apart, stress between the plates causes a series of faults to form along the rift zone.

Review Chapter 7 What are the two types of stress? Section 4 Deforming the Earth’s Crust Review What are the two types of stress? What are the three types of folds? Which side of the fault is the hanging wall and which is the footwall? A normal fault is one in which the hanging wall moves ______ A reverse fault is one in which that hanging wall move ______ A _________ ________ fault is one in which the fault blocks slide past one another horizontally.

Chapter 7 Plate Tectonics Concept Map Use the terms below to complete the concept map on the next slide. transform boundaries tectonic plates divergent boundaries converge diverge

Chapter 7 Plate Tectonics

Chapter 7 Plate Tectonics

End of Chapter 7

Chapter 7 2. Where do you think mountain building is taking place? Standardized Test Preparation 2. Where do you think mountain building is taking place? F between the African and South American plates G between the Nazca and South American plates H between the North American and Eurasian plates I between the African and North American plates

Chapter 7 2. Where do you think mountain building is taking place? Standardized Test Preparation 2. Where do you think mountain building is taking place? F between the African and South American plates G between the Nazca and South American plates H between the North American and Eurasian plates I between the African and North American plates

Chapter 7 Math Read each question, and choose the best answer. Standardized Test Preparation Math Read each question, and choose the best answer.

Chapter 7 Standardized Test Preparation 1. The mesosphere is 2,550 km thick, and the asthenosphere is 250 km thick. If you assume that the lithosphere is 150 km thick and that the crust is 50 km thick, how thick is the mantle? A 2,950 km B 2,900 km C 2,800 km D 2,550 km

Chapter 7 Standardized Test Preparation 1. The mesosphere is 2,550 km thick, and the asthenosphere is 250 km thick. If you assume that the lithosphere is 150 km thick and that the crust is 50 km thick, how thick is the mantle? A 2,950 km B 2,900 km C 2,800 km D 2,550 km

Chapter 7 Standardized Test Preparation 2. If a seismic wave travels through the mantle at an average velocity of 8 km/s, how many seconds will the wave take to travel through the mantle? F 318.75 s G 350.0 s H 362.5 s I 368.75 s

Chapter 7 Standardized Test Preparation 2. If a seismic wave travels through the mantle at an average velocity of 8 km/s, how many seconds will the wave take to travel through the mantle? F 318.75 s G 350.0 s H 362.5 s I 368.75 s

Chapter 7 Standardized Test Preparation 3. If the crust in a certain area is subsiding at the rate of 2 cm per year and has an elevation of 1,000 m, what elevation will the crust have in 10,000 years? A 500 m B 800 m C 1,200 m D 2,000 m

Chapter 7 Standardized Test Preparation 3. If the crust in a certain area is subsiding at the rate of 2 cm per year and has an elevation of 1,000 m, what elevation will the crust have in 10,000 years? A 500 m B 800 m C 1,200 m D 2,000 m

Chapter 7 Standardized Test Preparation 4. A very small oceanic plate is located between a mid-ocean ridge and a subduction zone. At the ridge, the plate is growing at a rate of 5 km every 1 million years. At the subduction zone, the plate is being destroyed at a rate of 10 km every 1 million years. If the oceanic plate is 100 km across, how long will it take the plate to disappear? F 100 million years G 50 million years H 20 million years I 5 million years

Chapter 7 Standardized Test Preparation 4. A very small oceanic plate is located between a mid-ocean ridge and a subduction zone. At the ridge, the plate is growing at a rate of 5 km every 1 million years. At the subduction zone, the plate is being destroyed at a rate of 10 km every 1 million years. If the oceanic plate is 100 km across, how long will it take the plate to disappear? F 100 million years G 50 million years H 20 million years I 5 million years