1. Earth’s Interior Chapter 2 Lesson 2
Students should copy underlined sections

2. Layers of the Earth
Brown
Grey

3. Composition of the Earth
The Earth is divided into 3 layers:
From outside in:
Crust
Mantle
Core
The Crust and Mantle are made of less dense material.
The Core is more dense than the crust and the mantle.

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

5. MANTLE 2,900 km thick The mantle is between the crust and core Thick
Contains most of Earth’s mass
Scientists study the mantle by looking at the composition of magma.
The magma from volcanoes is able to give scientists clues about the mantle’s composition.

6. CORE Innermost layer Made mostly of iron and nickel Made of two parts
Inner core – solid layer
Outer core – liquid layer

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

8. Lithosphere Outermost layer of Earth Made of crust and upper mantle
Divided into smaller pieces called tectonic plates.
The crust is divided into continental plates which drift very slowly (only centimeters each year) atop the less rigid mantle. The oceanic crust is thinner under the ocean (usually less than 10 km thick). Continental crust (land) is about km thick. About 40% of Earth’s surface is continental crust. The lithosphere is defined as the rigid out layer of Earth consisting of the crust and the upper mantle; approximately km thick.

9. Asthenosphere – “Plastic Layer”
The layer below Lithosphere and consists of the upper mantle
Pieces of lithosphere (the tectonic plates) move on top of this layer.
Made of solid rock, soft layer of the mantle
The asthenosphere is solid due to the high pressures from above even though it is at very hot temperatures of about 1,600℃. At this temperature, minerals are almost ready to melt and they become ductile and can be deformed like silly putty in response to the warmth of the Earth without losing its toughness. These rocks flow, moving in response to the stresses placed upon them by the churning motions of the deep interior of the Earth’s convection currents. The flowing asthenosphere carries the lithosphere (continents) on its back.

10. Mesosphere Below the asthenosphere Strong lower part of mantle
Extends to the Earth’s core, but does not consist of the core.
The mesosphere refers to the part of the Earth's mantle below the lithosphere and the asthenosphere, but above the outer core. It is made of magma, oxygen, silicon, and magnesium.

11. Outer Core Liquid layer of Earth’s core Surrounds inner core
Approximately 2,300 km thick
Composed mostly of iron and nickel

12. Inner Core Solid dense center of Earth About 1,220 km radius
Composed of iron-nickel alloy and some light elements
Only 30% smaller than the Moon

13. Quiz
Name the three compositional layers of the Earth from the inside out.
What is the most dense layer of Earth?
Which layer is the thinnest?
What are the two types of crust?
Which layer contains most of Earth’s mass?
What are the 5 physical layers of Earth?
What two layers make up the lithosphere?
What are tectonic plates?
Pieces of lithosphere move on top of which layer?
Which layer is said to be “plastic”. Why?
Which layer of the core is solid?
Which layer of the core is liquid?

14. Answers Core, Mantle, Crust Core Crust Continental and oceanic crusts
Lithosphere, Asthenosphere, Mesosphere, Outer Core, and Inner Core
Crust and upper mantle
The pieces that the lithosphere is divided into
Asthenosphere
Asthenosphere; 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 inside Earth
Inner core
Outer core