1. A Journey to the Center of the Earth
The Earth’s Structure
A Journey to the Center of the Earth

2. The Earth’s Surface Hydrosphere: Atmosphere: All the Earth’s water
The earth is 71% covered by water
97% is salt water
Atmosphere:
Thick blanket of gases surrounding the earth

3. The Interior of the Earth

4. The Earth’s Layers
Earth can be divided into three main layers – the crust, mantle and core.
The layering is due to differences in density
Temperature and pressure in Earth’s interior increase with depth

5. The Crust Rocky outer layer of Earth Made up of Silicates
Two types of Crust
Continental Crust – rocks that make up continents; thickness between km
Oceanic Crust – rock that makes up ocean floor; average thickness 7 km

6. Review What does the prefix hydro- mean?
List the three main layers of the earth’s interior?
Explain why the layers of the earth stay in place?
Water makes up ____ of the earth’s surface.
Name the two types of crust. What is the difference between the two types?

7. The Mantle A thick layer of hot semi-solid dense rock
Approximately 2850 km thick
Composed of mostly iron, magnesium and aluminum.
Makes up about 84% of Earth’s volume

8. The Moho The boundary between the crust and the mantle.
The mantle is denser than its crust
Mohorovicic discontinuity

9. “Sub Layers” w/n Crust & Mantle
Lithosphere – composed of the oceanic and continental crust and the rigid upper mantle; thin outer shell of Earth; broken up into “plates”.
Asthenosphere – softer and weaker rock in the mid-mantle; can flow slowly when under pressure
Mesosphere – stronger lower part of the mantle

10. The Core A large sphere of metal that occupies Earth’s center
Composed mostly of iron and nickel
Divided into 2 parts:
Outer core – composed of liquid metal; km thick
Inner core – solid due to very high pressure; 1220 km thick

12. How do Scientists study Interior of Earth?
Use of Seismic Waves (Earthquakes)
2 Types of Seismic Waves: S & P waves
P waves:
Travel through solids, liquids and gases
Faster than S waves
S waves
Travel only through solids

13. How do Scientists study Interior of Earth?
Speed and direction of both waves are affected by the composition of material they are traveling through
For example:
The changes in the seismic waves mark the boundary between the mantle and outer core.
Both P and S waves travel faster through more rigid materials

14. Shadow Zones
Locations on Earth’s surfaces where neither S or P waves are detected
S waves will not travel through liquid core
P waves speed and direction change causing them to bend

15. Review What are the two types of seismic waves?
How are seismic waves used to determine the layers of the earth?
Which layer is a liquid?
Which layers compose the lithosphere?
What state of matter is the inner core?

16. What is a compass?

17. The Earth as a Magnet
Source of the earth’s magnetic field is the movement of liquid iron in the outer core.
The motion produces electrical currents which create a magnetic field.

18. Magnetosphere
The region of space which is affected by the earth’s magnetic field.
affects the earth and an area that extends beyond the atmosphere.