4-1: Earth’s Interior

6th Grade Earth Science

4-1: Earth’s Interior

• Scientists use two ways to find the answer:

1. Direct evidence from rocks.

2. Indirect evidence from Seismic Waves.

What’s Inside the Earth?

4-1: Earth’s Interior

• Scientists drill holes up to 12 km deep to get rock samples.

• They also get temperature and pressure data.

Direct Evidence

German deep drilling project

4-1: Earth’s Interior

• Volcanoes eject material from up to 100 km deep.

• This is more direct evidence of what is down there !!!

4-1: Earth’s Interior

• Scientists use seismic waves to get indirect evidence.

• They look at:

1. Change in speed

2. Change in path

Indirect Evidence

4-1: Earth’s Interior

• From this scientists know there are 3 main layers:

1. Crust

2. Mantle

3. Core

4-1: Earth’s Interior

• Temperature increases (hotter) as you go down.

• Pressure increases (gets higher) as you go down.

Temperature and Pressure

4-1: Earth’s Interior

• A thin layer of solid rock - includes dry land and the land under the ocean.

• 5 to 70 km thick.

The Crust

4-1: Earth’s Interior

• Hot layer of solid rock 3000 km thick.

• It has several layers with different physical characteristics.

The Mantle

4-1: Earth’s Interior

• Hottest layer made mostly of the metals iron and nickel – 3500 km thick.

• It has two parts, inner core of solid metal and outer core of liquid metal.

The Core

4-1: Earth’s Interior

• Lithosphere is the crust and the solid upper layer of the mantle.

• Asthenosphere is a softer, hot rock layer just below the lithosphere.

• Lower Mantle is solid rock down to the outer core.

Mantle Details

4-1: Earth’s Interior

• The Earth acts like a large bar magnet.

• Scientist believe the magnetic field is produced in the moving liquid metal in the outer core.

Earth’s Magnetic Field

4-1: Earth’s Interior

4-1: Earth’s Interior Summary

1. Scientists use direct and indirect evidence to understand Earth’s insides.

2. The Earth has three main layers: Crust, Mantle, and Core.

3. The Mantle layer has 3 layers.

4. The Core has 2 layers.

5. Earth has a magnetic field like a bar magnet.