6.3 Notes Earth’s Layers

Unit 6 Lesson 3 Earth’s Layers Florida Benchmarks SC.7.E.6.1 Describe the layers of the solid Earth, including the lithosphere, the hot convecting mantle, and the dense metallic liquid and solid cores. SC.7.E.6.7 Recognize that heat flow and movement of material within Earth causes earthquakes and volcanic eruptions, and creates mountains and ocean basins. Copyright © Houghton Mifflin Harcourt Publishing Company 2

Unit 6 Lesson 3 Earth’s Layers Florida Benchmarks MA.6.A.3.6 Construct and analyze tables, graphs, and equations to describe linear functions and other simple relations using both common language and algebraic notation. Copyright © Houghton Mifflin Harcourt Publishing Company 3

Remember our lesson goal! What are Earth’s Layers?

What is inside Earth? Earth is made of several layers. Unit 6 Lesson 3 Earth’s Layers What is inside Earth? Earth is made of several layers. Each layer has its own characteristic properties. Scientists think about Earth’s layers in two ways—in terms of chemical composition, and in terms of physical properties. Copyright © Houghton Mifflin Harcourt Publishing Company 5

What are Earth’s compositional layers? Unit 6 Lesson 3 Earth’s Layers What are Earth’s compositional layers? Earth can be divided into three layers based on chemical composition: the crust, the mantle, and the core. Copyright © Houghton Mifflin Harcourt Publishing Company 6

The outermost solid layer of Earth is the crust. Unit 6 Lesson 3 Earth’s Layers What are Earth’s compositional layers? The outermost solid layer of Earth is the crust. There are two types of crust: continental and oceanic. Copyright © Houghton Mifflin Harcourt Publishing Company 7

What are Earth’s compositional layers? Unit 6 Lesson 3 Earth’s Layers What are Earth’s compositional layers? Both types of crust are made mostly of oxygen, silicon, and aluminum. Oceanic crust is denser than continental crust because it contains almost twice as much iron, calcium, and magnesium. Copyright © Houghton Mifflin Harcourt Publishing Company 8

What are Earth’s compositional layers? Unit 6 Lesson 3 Earth’s Layers What are Earth’s compositional layers? The mantle is located between the crust and the core. The mantle is a region of hot, slow-flowing solid rock. The mantle contains more magnesium and less aluminum and silicon than the crust. Copyright © Houghton Mifflin Harcourt Publishing Company 9

What are Earth’s compositional layers? Unit 6 Lesson 3 Earth’s Layers What are Earth’s compositional layers? Convection is the movement of heated material as a result of differences in density. Convection in the mantle causes cooler rock to sink and warmer rock to rise. Copyright © Houghton Mifflin Harcourt Publishing Company 10

What are Earth’s compositional layers? Unit 6 Lesson 3 Earth’s Layers What are Earth’s compositional layers? The core extends from below the mantle to the center of Earth. Scientists think the core is made mostly of iron and some nickel. The core is the densest layer and makes up about one-third of Earth’s mass. Copyright © Houghton Mifflin Harcourt Publishing Company 11

What are Earth’s physical layers? Unit 6 Lesson 3 Earth’s Layers What are Earth’s physical layers? Earth is also divided into layers based on physical properties, such as whether the layer is solid or liquid. The five physical layers are the lithosphere, asthenosphere, mesosphere, outer core, and inner core. Copyright © Houghton Mifflin Harcourt Publishing Company 12

What are Earth’s physical layers? Unit 6 Lesson 3 Earth’s Layers What are Earth’s physical layers? The outermost, rigid layer of Earth is the lithosphere. The lithosphere is made of the crust and the upper part of the mantle. The lithosphere is divided into tectonic plates. Copyright © Houghton Mifflin Harcourt Publishing Company 13

What are Earth’s physical layers? Unit 6 Lesson 3 Earth’s Layers What are Earth’s physical layers? The asthenosphere is the layer of the mantle made of solid rock that moves very slowly. The asthenosphere is located below the lithosphere. Tectonic plates move on top of the asthenosphere. Copyright © Houghton Mifflin Harcourt Publishing Company 14

What are Earth’s physical layers? Unit 6 Lesson 3 Earth’s Layers What are Earth’s physical layers? The strong, lower part of the mantle is called the mesosphere. Rock in the mesosphere flows more slowly than rock in the asthenosphere. Copyright © Houghton Mifflin Harcourt Publishing Company 15

What are Earth’s physical layers? Unit 6 Lesson 3 Earth’s Layers What are Earth’s physical layers? The outer core is the liquid layer of Earth’s core. The outer core lies beneath the mantle and surrounds the inner core. Copyright © Houghton Mifflin Harcourt Publishing Company 16

What are Earth’s physical layers? Unit 6 Lesson 3 Earth’s Layers What are Earth’s physical layers? The inner core is the solid, dense center of our planet. The inner core extends from the bottom of the outer core to the center of Earth. Copyright © Houghton Mifflin Harcourt Publishing Company 17

The physical layers of the inner core and outer core form a single compositional layer. The mantle is also part of the rigid upper part of the lithosphere

This would be an example of lithosphere

6.4 Notes Plate Tectonics Copyright © Houghton Mifflin Harcourt Publishing Company 20

Unit 6 Lesson 4 Plate Tectonics Florida Benchmarks SC.7.N.1.5 Describe the methods used in the pursuit of a scientific explanation as seen in different fields of science such as biology, geology, and physics. SC.7.E.6.1 Describe the layers of the solid Earth, including the lithosphere, the hot convecting mantle, and the dense metallic liquid and solid cores. Copyright © Houghton Mifflin Harcourt Publishing Company 21

Unit 6 Lesson 4 Plate Tectonics Florida Benchmarks SC.7.E.6.2 Identify the patterns within the rock cycle and relate them to surface events (weathering and erosion) and sub-surface events (plate tectonics and mountain building). SC.7.E.6.5 Explore the scientific theory of plate tectonics by describing how the movement of Earth’s crustal plates causes both slow and rapid changes in Earth’s surface, including volcanic eruptions, earthquakes, and mountain building. Copyright © Houghton Mifflin Harcourt Publishing Company 22

Unit 6 Lesson 4 Plate Tectonics Florida Benchmarks SC.7.E.6.7 Recognize that heat flow and movement of material within Earth causes earthquakes and volcanic eruptions, and creates mountains and ocean basins. LA.6.2.2.3 The student will organize information to show understanding (e.g., representing main ideas within text through charting, mapping, paraphrasing, summarizing, or comparing/contrasting). Copyright © Houghton Mifflin Harcourt Publishing Company 23

Remember our lesson goal What is plate tectonics?

What evidence suggests that continents move? Unit 6 Lesson 4 Plate Tectonics What evidence suggests that continents move? In the late 1800s, Alfred Wegener proposed his hypothesis of continental drift. According to the continental drift hypothesis, the continents once formed a single landmass, broke up, and drifted. Copyright © Houghton Mifflin Harcourt Publishing Company 25

What evidence suggests that continents move? Unit 6 Lesson 4 Plate Tectonics What evidence suggests that continents move? Several lines of evidence supported Wegener’s hypothesis. Fossils of the same species are found on continents on separate sides of the Atlantic Ocean. The locations of mountain ranges and rock formations and evidence of ancient climatic conditions also supported Wegner’s hypothesis. Copyright © Houghton Mifflin Harcourt Publishing Company 26

Unit 6 Lesson 4 Plate Tectonics What is Pangaea? Today, scientists accept that the continents were once joined. About 245 million years ago, the continents were joined in a single large landmass called Pangaea. Over millions of years, Pangaea broke into fragments that drifted and collided with each other. Copyright © Houghton Mifflin Harcourt Publishing Company 27

Pangaea Unit 6 Lesson 4 Plate Tectonics 28 Copyright © Houghton Mifflin Harcourt Publishing Company 28

What discoveries support the idea of continental drift? Unit 6 Lesson 4 Plate Tectonics What discoveries support the idea of continental drift? Scientists did not accept Wegener’s ideas because they could not determine how continents moved. In the mid-1900s, scientists began mapping the sea floor and discovered features that supported some of Wegener’s ideas. Copyright © Houghton Mifflin Harcourt Publishing Company 29

What discoveries support the idea of continental drift? Unit 6 Lesson 4 Plate Tectonics What discoveries support the idea of continental drift? Scientists discovered that oceanic crust is young compared to continental crust. They also discovered that sea floor rock contains magnetic patterns. A process called sea-floor spreading explains the age and magnetic pattern of sea floor rocks. Copyright © Houghton Mifflin Harcourt Publishing Company 30

What discoveries support the idea of continental drift? Unit 6 Lesson 4 Plate Tectonics What discoveries support the idea of continental drift? Through sea-floor spreading, molten rock rises at the ridges and forms new oceanic crust. Sea-floor spreading occurs at divergent boundaries where the plates are moving away from each other Older crust is pushed away from the ridge, and the sea floor slowly spreads apart. Scientists also discovered huge trenches in the sea floor where oceanic crust sinks into the asthenosphere. Copyright © Houghton Mifflin Harcourt Publishing Company 31

What is the theory of plate tectonics? Unit 6 Lesson 4 Plate Tectonics What is the theory of plate tectonics? Scientists began to form a new theory to explain how tectonic plates move. Plate tectonics is a theory that describes large-scale movements of Earth’s lithosphere. It describes why and how continents move and explains how many of the features on Earth’s crust form. Copyright © Houghton Mifflin Harcourt Publishing Company 32

What is a tectonic plate? Unit 6 Lesson 4 Plate Tectonics What is a tectonic plate? The lithosphere is divided into pieces called tectonic plates, which move around on top of the asthenosphere. Copyright © Houghton Mifflin Harcourt Publishing Company 33

What are three types of plate boundaries? Unit 6 Lesson 4 Plate Tectonics What are three types of plate boundaries? The three types of plate boundaries are convergent boundaries, divergent boundaries, and transform boundaries. Each type is associated with characteristic landforms. Copyright © Houghton Mifflin Harcourt Publishing Company 34

What are three types of plate boundaries? Unit 6 Lesson 4 Plate Tectonics What are three types of plate boundaries? Convergent boundaries form where two plates collide. This can happen in three ways, depending on the type of crust that is involved. Copyright © Houghton Mifflin Harcourt Publishing Company 35

What are three types of plate boundaries? Unit 6 Lesson 4 Plate Tectonics What are three types of plate boundaries? At a divergent boundary, two plates move away from each other, and magma forms new lithosphere at mid-ocean ridges. Copyright © Houghton Mifflin Harcourt Publishing Company 36

What are three types of plate boundaries? Unit 6 Lesson 4 Plate Tectonics What are three types of plate boundaries? A boundary at which two plates move past each other horizontally is called a transform boundary. At transform boundaries, the motion of the two plates often produces earthquakes. Copyright © Houghton Mifflin Harcourt Publishing Company 37

What causes tectonic plates to move? Unit 6 Lesson 4 Plate Tectonics What causes tectonic plates to move? Scientists have proposed three mechanisms to explain how tectonic plates move over Earth’s surface. Some evidence suggests that convection, or the movement of material due to differences in density, in the mantle drags the overlying tectonic plates along with it. Copyright © Houghton Mifflin Harcourt Publishing Company 38

Earthquakes and volcanoes are a result of the motion of materials caused by high temperatures in Earth’s mantle. This is due to tectonic plate movement, which causes earthquakes and volcanoes, and occurs as a result of convection currents in the mantle, which form because the mantle is warmer at the bottom than at the top

What causes tectonic plates to move? Unit 6 Lesson 4 Plate Tectonics What causes tectonic plates to move? The mechanism called ridge push suggests that as lithosphere sinks, the plates are pushed away from the mid-ocean ridge. The crust along the mid-ocean ridge is less dense. As it cools, it becomes denser and sinks into the mantle, pulling it away from the ridge. The force of the asthenosphere below pushes the rest of the plate away from the mid-ocean ridge. Copyright © Houghton Mifflin Harcourt Publishing Company 40

What causes tectonic plates to move? Unit 6 Lesson 4 Plate Tectonics What causes tectonic plates to move? The mechanism called slab pull suggests that plates move because sinking plates pull them. The leading edge of a sinking plate is colder and denser than the mantle, so it sinks. The rest of the plate follows. Many scientists think slab pull is the most important mechanism driving plate motion. Copyright © Houghton Mifflin Harcourt Publishing Company 41

Notice how the figure below shows both continental crust and oceanic crust. In this figure, shading indicates density. The more darkly shaded a region is, the denser that region is. You infer from the figure that oceanic crust is more dense than continental crust.

The figure shows part of what scientists think is happening in Earth’s mantle. The process occurring in the mantle is as hot rock expands it becomes less dense, and rises toward the surface of Earth.