1. Earth’s Interior Layers
© Copyright 2006.  M. J. Krech. All rights reserved.

2. The Four Layers

3. How do scientists know and learn about Earth’s interior?
Direct Evidence
rock samples and lava
**Indirect Evidence
seismic waves

4. The Crust
*like the skin of an apple - very thin in comparison to other layers
* only about 3-5 miles (8 kilometers) thick under oceans (oceanic crust)
* about 25 miles (32 kilometers) thick under the continents (continental crust).

5. The Crust composed of two main types of rock
composed of two main types of rock
continental crust is mostly granite & oceanic crust is basalt
basalt is much denser than the granite
less dense continents ride on the denser oceanic plates.

6. Lithosphere
crust and the upper layer of the mantle together make up this zone of rigid, brittle, solid rock

7. The Lithospheric Plates
The crust of the Earth is broken into many pieces called tectonic plates. These plates "float" on the asthenosphere.

8. Scientists think that movement here is the reason tectonic plates move
Asthenosphere
semi-rigid part of the middle mantle that flows like hot asphalt or plastic
Scientists think that movement here is the reason tectonic plates move

9. The Mantle largest layer of the Earth
composed of very hot dense rock that is capable of flow like asphalt under a heavy weight
The movement of the middle mantle (asthenosphere) is the reason that the tectonics plates of the Earth move.

10. Convection Currents What is convection? Where is the heat source?
Asthenosphere "flows" because of convection currents.
What is convection? Where is the heat source?

11. The Outer Core ball of very hot metals
ball of very hot metals
so hot that the metals in it are all in the liquid state
The outer core is composed mainly of liquid nickel and iron.
Scientists think that spinning movement in the liquid outer core is the reason for Earth’s magnetic field.

12. The Inner Core
temperatures and pressures so great that metals are squeezed together and are not able to move about like a liquid, but are forced to vibrate in place like a solid.

13. Earth's Interior Interactive
Click the links below for more about Earth’s Interior and plate tectonics!
Earth's Interior Interactive
Earth's Interior Rap :)
Bill Nye video clip (12 min)