Inside the Earth-Pages 190-193 Chapter 7 Section 1 Inside the Earth-Pages 190-193

Layers of the Earth Brown Blue

Composition of the Earth The Earth is divided into 3 layers: Crust Mantle Core The Crust and Mantle are made of less dense compound. The Core is more dense that the crust and mantle.

CRUST The outermost layer 5-100 km thick Thinnest layer 2 types of crust Continental- thick Oceanic-thin

MANTLE 2900 km thick Between the crust and core Thick Contains most of Earth’s mass Scientists study the mantle by looking at the composition of magma. Magma from volcanoes gives scientists clues about the composition of the mantle.

CORE Innermost layer Made mostly of iron and nickel Inner core solid Outer core liquid Core

Physical Properties of Earth Earth divided into 5 physical layers: Lithosphere Asthenosphere Mesosphere Outer Core Inner Core

Lithosphere Outermost layer of Earth Made of crust and upper mantle Divided into pieces called tectonic plates. The crust is divided into continental plates which drift slowly (only a few centimeters each year) atop the less rigid mantle. The crust is thinner under the oceans (6-11 km thick); this is where new crust is formed. Continental crust is about 25-90 km thick. The lithosphere is defined as the crust and the upper mantle, a rigid layer about 100-200 km thick. The Mohorovicic discontinuity is the separation between the crust and the upper mantle.

Asthenosphere Layer below Lithosphere Pieces of lithosphere (tectonic plates) move along this layer. Made of solid rock, soft layer of the mantle The asthenosphere is solid even though it is at very hot temperatures of about 1600 C due to the high pressures from above. However, at this temperature, minerals are almost ready to melt and they become ductile and can be pushed and deformed like silly putty in response to the warmth of the Earth. These rocks actually flow, moving in response to the stresses placed upon them by the churning motions of the deep interior of the Earth. The flowing asthenosphere carries the lithosphere of the Earth, including the continents, on its back.

Mesosphere Below the asthenosphere Strong lower part of mantle Extends to the Earth’s core

Outer Core Liquid layer of Earth’s core Surrounds inner core

Inner Core Solid dense center

Quiz 1. Name the three main layers of the Earth. 2. Which layer is the most dense? 3. Which layer is the thinnest? 4. What are the two types of crust? 5. Which layer contains most of Earth’s mass? 6. What two layers make up the lithosphere? 7. The lithosphere is divided into pieces called: 8. Pieces of lithosphere move on top of this layer: 9. The Asthenosphere is said to be “plastic”. What does this mean? 10. Which layer, inner core or outer core, is liquid? 11. Which layer, the inner core or the outer core, is solid?

Answers 1.Crust, mantle and core 2. Core 3. Crust 4. Continental and oceanic 5. Mantle 6. Crust and upper mantle 7. Tectonic Plates 8. Asthenosphere 9. Because it is very hot and made of partially molten rock it bends and can be pushed and deformed due to the pressure placed on it from deep within the Earth. 10. Outer core 11. Inner core