Chapter 2, Lesson 3, Earth’s Interior

Chapter 2, Lesson 3, Earth’s Interior Slide 1 *What is the main idea? -What are layers? *Earth’s interior has a layered structure. -Earth’s interior is made up of different compositions called layers. -The temperatures and pressures within Earth increase as you go deeper inside.

Chapter 2, Lesson 3, Earth’s Interior Slide 2 *What happens when seismic waves travel through layers? *Earthquakes produce seismic waves that pass through the planet. *The speed and direction of the seismic waves change when the properties of the Earth materials they are traveling through change. *The waves bounce off or bend as they approach a new layer. *Scientists have learned about the Earth’s layers by analyzing the paths of these waves.

Chapter 2, Lesson 3, Earth’s Interior Slide 3 Seismic Waves

Chapter 2, Lesson 3, Earth’s Interior Slide 4 -What is the Earth’s crust? -The thin, rocky, outer layer of Earth is called the crust. -Scientists have indicated that there are two different types: Crust under the oceans (oceanic), is made from igneous rock called basalt. Crust on the continents (continental), is made of igneous rock that is much like granite. -Continental crust is less dense and thicker than oceanic crust because oceanic crust is made of higher density minerals.

Chapter 2, Lesson 3, Earth’s Interior Slide 6 *What is the mantle? *The mantle is the thick middle layer below the crust of the Earth’s interior. *The rock in the upper part of the mantle is called periodotite. *Minerals in mantle rocks have tightly packed crystal structures and are heavy in iron. *Mantle rocks are denser than rocks in the crust. *The area of the mantle that is 100km to 250km deep is so hot that tiny bits of rock melt. *This plastic but mostly solid layer of the mantle is called the asthenosphere.

Chapter 2, Lesson 3, Earth’s Interior Slide 7 *What is the mantle? continued *The plastic melted rock of the asthenosphere flows very slowly and moves at a rate of only a few centimeters per year. *Below the asthenosphere the rock is solid and hotter. *This rock doesn’t melt because the increased pressure reduces melting. *The pressures deep within Earth are so great that they squeeze hot rock material into a solid state.

Chapter 2, Lesson 3, Earth’s Interior Slide 8 The Mantle

Chapter 2, Lesson 3, Earth’s Interior Slide 9 -What is the lithosphere? -The lithosphere is the brittle outer layer of Earth. -The lithosphere is located between the uppermost mantle and the crust of the Earth.

Chapter 2, Lesson 3, Earth’s Interior Slide 10 *What is the core? *The dense metallic part of Earth is called the core. *It is the densest part of the planet because it is made mainly of metallic elements, iron with some nickel. *The core is divided into two layers: The outer core is a layer of molten metal because the effects of temperature outweigh that of pressure. The inner core has a higher pressure and causes the metal to be in a solid state.

Chapter 2, Lesson 3, Earth’s Interior Slide 11 The Mysteries Of the Earth’s Core

Chapter 2, Lesson 3, Earth’s Interior Slide 12 -What is heat transfer in Earth? *How do the layers of Earth affect density? -Heat movement in a fluid is called convection. -Convection processes transfer heat in the outer core and in the mantle. -This transfer process is driven by changes in density. *Temperature and pressure can affect density. *As the temperature of a material is raised, its density decreases. *This happens because material expands when heated and it takes up more space, but it becomes less dense.

Chapter 2, Lesson 3, Earth’s Interior Slide 13 *How do the layers of Earth affect density? continued *The three major layers have distinct compositions, and therefore, have different densities. *Most elements that make up mantle and crust rocks are less dense than material in the core, so as the metallic core material sank, mantle and crust matter moved up toward the surface. *The rocks in the crust are the least dense of all rocks.

Chapter 2, Lesson 3, Earth’s Interior Slide 14

Chapter 2, Lesson 3, Earth’s Interior Slide15 -What is convection like in the Core and Mantle? -Thermal energy on Earth’s outer core and mantle escapes toward the surface mostly by convection. -As Earth spins on its axis, convection currents of molten iron produce a magnetic field around the planet. -This causes Earth to act a little like a huge bar magnet. -Convection in the mantle is important for plate tectonics. -Though the mantle is made of mostly solid rock, scientists have discovered that solid rock can flow. -The flow takes place slowly.

Chapter 2, Lesson 3, Earth’s Interior Slide 16 Magnetic Field

Chapter 2, Lesson 3, Earth’s Interior Slide 17 *Summary: -Layering of Earth started when Earth first formed millions of years ago. -Trying to dig a hole in Earth’s interior is impossible. -Using earthquakes and other vibrations helped scientists find out about Earth’s interior. -The mostly solid, materials in Earth’s interior continue to move. -As long as this movement of matter occurs, heat escapes and changes Earth’s surface by uplift in some regions.

Questions???? What are the two types of Earth’s crust? What is the thick middle layer below Earth’s crust called? Which is the plastic mostly solid layer of the mantle called? How many layers make up Earth’s interior? What produces Earth’s magnetic field?