1. Earth’s Layers
Geology Unit

2. Learning Objectives
I can describe the properties of Earth’s three layers.
I can compare and contrast Earth’s three layers.
I can explain convection currents and how they work.

3. DEFINE… Crust Continental Crust Oceanic Crust Mantle Lithosphere
Asthenosphere
Outer Core
Inner Core
Density
Volume
Convection Currents

4. Introduction to Earth’s Layers

5. The Crust
The Mantle
The Core
Three Layers

6. 5 – 25 miles thick The Crust The surface of Earth. The thinnest layer.
Made of solid rock.
Contains all the mountains, rocks, water, soil and land features.
Contains the lithosphere, oceanic crust and continental crust.
5 – 25 miles thick
The Crust

7. Lithosphere Made from the Crust and Upper Mantle.
“Litho” means “stone” in Greek.
This is the layer in which we live because it contains the oceanic and continental crust.
Lithosphere

8. Crust
Lithosphere

9. Oceanic versus Continental Crust
5 – 25 miles thick
Oceanic Crust:
Below the ocean
Consists of basalt
Very dense
Continental Crust:
Forms and contains the large landmasses
Consists of granite
Less dense
3 - 5 miles thick

10. The Mantle 1,800 miles thick Divided into two parts: Upper mantle
Lower mantle.
Most of the mantle is solid rock.
The lower mantle rock is softer.
It makes up 85% of the Earth’s mass.
Temperatures can reach up to 870 C.
1,800 miles thick

11. Asthenosphere Zone in the Upper Mantle.
Lithosphere floats on top of it.
Consists of hot, plastic rock.
“Asthens” means “weak” in Greek.

12. Crust
Lithosphere
Asthenosphere

13. Transfer of Heat
Radiation – The transfer of energy through space, such as the transfer of heat from the Sun.
Conduction – The transfer of heat within a material or between two materials that are touching.
Convection – The transfer of heat by the movement of currents within a fluid.

14. REMEMBER:
Volume is THE AMOUNT OF SPACE AN OBJECT TAKES UP. If a liquid is heated to a gas, it will take up more space than before.

15. Convection Currents Density = Mass Volume
What are Convection Currents???
The process of liquid heating and cooling in between the mantle and outer core of the Earth.
When a liquid is heated, the particles spread apart. This is due to the fact that their energy is being converted into kinetic energy (the energy of movement). Once these molecules spread out, their volume increases causing their density to decrease. Therefore, the hot liquid floats to the top and the cooler water, which has decreased in volume and increased in density, sinks to the bottom.
This process occurs, repeatedly, in the mantle due to the heat from the core and mantle.

16. Convection Currents Takes place between the Mantle and the Outer Core.
Since the density of the liquid decreased, it floated up, towards the surface.

17. The Core Outer Core Inner Core The Core is Divided into two parts:

18. Outer vs. Inner Core Outer Core – only liquid layer! Inner Core
Made up of liquid iron and nickel.
This layer creates the Earth’s magnetic field.
Temperatures can reach up to 2,200 C.
Inner Core
The center of Earth.
Made up of scorching-hot iron and nickel. This layer stays solid though due to intense pressure.
This layer may also contain oxygen, sulfur and silicon.
Temperatures range between 9,000 C and 13,000 C.

19. Evidence How do Scientists know about the interior of the Earth?
Two forms of evidence:
Direct evidence from rock samples
Indirect evidence from seismic waves
Evidence

20. Review… 5
Can you name the different layers of the Earth?? Number a piece of paper 1 -5 and write the name of each layer. 4 3 2 1

21. Review… Inner Core Outer Core Lower Mantle Upper Mantle Crust 5 4 3 21