1. Earth’s Layers
S6E5.a. Compare and contrast the Earth’s crust, mantle, and core including temperature, density, and composition.

2. We Have 2 ways of Dividing Earth’s Layers:

3. Earth is divided into 3 compositional layers:
1. Crust
2. Mantle
3. Core

4. CRUST:
Location: outermost layer
Temperature: 0°C to 1,000°C
Thickness: 5km to 100 km
Composition:
Oxygen
Silicon
Aluminum

5. 2 TYPES OF CRUST:
Oceanic crust is very thin & dense.
Continental crust is thick but less dense.

7. MANTLE:
Location: below the crust.
Temperature: 1,000°C to 3,700°C
Thickness: 2,900 km
Composition:
Contains most of Earth’s mass
Solid and molten rock

8. CORE:
Location: Earth’s center
Temperature: 3,700°C - 7,000°C
Thickness: 3,500 km
Composition: mostly iron, some nickel
Divided into 2 layers:
Outer Core
Inner Core

9. Earth is divided into 5 physical layers:
1. Lithosphere
2. Asthenosphere
3. Mesosphere
4. Outer Core
5. Inner Core

10. LITHOSPHERE:
This is the “crunchy” layer of the Earth.
Location: crust and upper mantle
Thickness: kilometers
Lithosphere = tectonic plates

11. ASTHENOSPHERE:
Location: the middle mantle, below the lithosphere
Soft – can bend like plastic
Lithosphere floats on this layer (like jello)
Thickness: 250 km

12. MESOSPHERE:
Location: the strong, lower part of the mantle
Thickness: 2,550 kilometers

13. Outer Core: Thickness: 2,300 km
Composition: liquid iron (with some nickel)
Thickness: 2,300 km

14. Inner Core:
Composition: solid iron and a little nickel.
Thickness: 1,220 km thick.
Solid because of increased pressure.

15. Lithosphere Asthenosphere Mesosphere CRUST MANTLE OUTER CORE
INNER CORE

16. Density, Pressure, and Temperature
Moving towards the center of the earth:
Density increases
Pressure increases
Temperature increases

17. How do we know there are layers of the earth?
Earthquakes emit different kinds of seismic waves that can travel through different substances and at different speeds
Scientists used these waves to determine the layers based on the speed and movement of the layers!

18. The MOHO
The Moho is the boundary where the crust meets the mantle
It was discovered in 1909 by Andrija Mohorovicic
It was discovered because at this point density changes and seismic waves change direction

19. The MOHO

20. Why does Earth have a magnetic field?

21. Why does Earth have a magnetic field?
Earth’s magnetic field is a result of the movement of iron in the Earth’s liquid inner core.

22. In Review:
What are the 3 main layers of the Earth?
Crust, Mantle, Core
Which layer is the least dense?
Crust
Which core layer is solid iron and nickel?
Inner core
What is the name given to the “crunchy” layer of the crust and uppermost part of the mantle?
Lithosphere
5. The motion in this layer is the reason Earth has a magnetic field.
Outer core