1. 8.4: Earth’s Layered Structure

2. I. Based on Chemical Composition
A. Three Layers
I. Based on Chemical Composition
1. Crust
Thin, rocky outer layer
2 types:
Oceanic
Made of igneous rocks - younger rock
Continental
Made of all rock types (mostly granite)
Older rock: over 4 billion years

3. 2. Mantle
Solid, rocky layer below crust
more dense than crust
makes up 82% of Earth
3. Core
• Inner most layer below mantle – 2 layers: outer and inner
• Very dense, highest pressure, made of iron-nickel
B. Each layer increases by temperature, density, and pressure from crust to core

4. C. Boundaries Moho Shadow Zone Separation between crust and mantle
Separation between mantle and outer core

5. II. Based on Physical Properties
A. 5 layers
II. Based on Physical Properties
1. Lithosphere
• Crust and upper mantle
• Cool, rigid, solid
2. Asthenosphere
• Beneath the lithosphere
• Middle mantle
• Soft, weak layer - easily deformed

6. 3. Lower Mantle 4. Outer Core 5. Inner Core
• flowing rock – rocks are very hot
4. Outer Core
• Liquid layer of iron - creates Earth’s magnetic field
5. Inner Core
Higher temps
Behaves like a
solid due to
pressure

7. Earth’s Layered Structure

8. III. Discovering Earth’s Layers
Seismic Data (Earthquakes)
Waves travel at different speeds in each layer
Waves bend when traveling through liquids or solids