7.7 Earth’s Interior

In A Journey to the Center of the Earth , what did they find?

Jules Verne published A Journey to the Center of the Earth in 1864 with very little idea of what was below the surface. Unfortunately, there are no volcanic tubes in which to travel deep within the planet, as Verne had imagined. But scientists have learned a lot about Earth’s interior using seismic waves, rocks, and calculations of Earth’s density and magnetism.

Other Clues about Earth’s Interior

1. Earth’s overall density is higher than the density of crustal rocks, so the core must be made of something dense, like metal.
2. Since Earth has a magnetic field, there must be metal within the planet. Iron and nickel are both magnetic.
3. Meteorites are the remains of the material that formed the early solar system and are thought to be similar to material in Earth’s interior ( Figure below ).

This meteorite contains silica minerals and iron-nickel. The material is like the boundary between Earth’s core and mantle. The meteorite is 4.2 billion years old.

Summary

• Earth’s density indicates that it must contain a significant amount of metal.
• Since Earth has a magnetic field, there must be metal inside.
• Meteorites formed elsewhere in the solar system but by similar processes indicate something about Earth’s interior.

Interactive Practice

Use this resource to answer the questions that follow.

1. Who discovered the Earth’s core?

2. How did he discover it?

3. What did he discover about the core?

4. What did Inge Lehmann discover?

5. What is the structure of the inner core?

6. What is the function of the outer core?

Review

1. Scientists know that Earth’s interior contains metal, but how do they know it’s in the core?

2. How does the meteorite in the photo above give clues as to what is found in Earth’s interior?

3. If a planet in our solar system has a magnetic field, what do we know about it?