1. The Layers of the Earth © Copyright 2006. M. J. Krech. All rights reserved.

2. The Four Layers The Earth is composed of four different layers. The crust is the layer that you live on, and it is the most widely studied and understood. The mantle is much hotter and has the ability to flow. The outer core and inner core are even hotter with pressures so great you would be squeezed into a ball smaller than a marble if you were able to go to the center of the Earth!

3. The Crust The Earth's Crust is like the skin of an apple. It is very thin in comparison to the other three layers. The crust is only about 3-5 miles (8 kilometers) thick under the oceans (oceanic crust) and about 25 miles (32 kilometers) thick under the continents (continental crust).

4. The Lithospheric Plates The crust of the Earth is broken into many pieces called plates. The plates "float" on the soft, semi-rigid asthenosphere.

5. The Asthenosphere The asthenosphere is the semi-rigid part of the middle mantle that flows like hot asphalt under a heavy weight.

6. The Lithosphere The crust and the upper layer of the mantle together make up a zone of rigid, brittle rock called the Lithosphere.

7. The Crust The crust is composed of two rocks. The continental crust is mostly granite. The oceanic crust is basalt. Basalt is much denser than the granite. Because of this the less dense continents ride on the denser oceanic plates.

8. What makes up the crust? Elements - Elements make up everything on the Earth and in the Solar System. Elements make up you and everybody and all the plants. Even soil is made up of elements. Elements have names like Oxygen, Carbon, and Hydrogen. There are over 100 elements! Like everything else, the four layers of the Earth are made up of different elements. Now let us look at the four different layers of the Earth and the elements that make them up!!!

9. Elements of the Crust Crust - The crust is the part of the Earth that we stand on everyday. The crust is the only part of the Earth that we can touch with our hands and see with our eyes everyday. Sand, clay, and humus are types of soils that are part of the crust! The crust is not very hot since it is on top. The temperature of the crust is different all over the world. The elements that make up the CRUST are: Calcium, Sodium, Aluminum

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

11. Convection Currents The middle mantle "flows" because of convection currents. Convection currents are caused by the very hot material at the deepest part of the mantle rising, then cooling and sinking again --repeating this cycle over and over.

12. Convection Currents The next time you heat anything like soup or water in a pan you can watch the convection currents move in the liquid. When the convection currents flow in the asthenosphere they also move the crust. The crust gets a free ride with these currents, like the cork in this illustration. Safety Caution: Don’t get your face too close to the boiling water!

13. The Mantle elements Mantle - The mantle is under the crust. The mantle is made up of really hot rock that is melted, called molten lava. The red flowing lava that comes out of a volcano is part of the mantle. The mantle is the largest layer of the Earth. The mantle has a temperature from 1600 degrees Fahreheit to 4000 degrees Fahrenheit! That's very hot! The elements that make up the MANTLE are: Iron, Magnesium, Aluminum, Silicon, Oxygen

14. The Outer Core The core of the Earth is like a ball of very hot metals. The outer core is so hot that the metals in it are all in the liquid state. The outer core is composed of the melted metals of nickel and iron.

15. The Inner Core The inner core of the Earth has temperatures and pressures so great that the metals are squeezed together and are not able to move about like a liquid, but are forced to vibrate in place like a solid.

16. The outer core elements Outer Core - The outer core is so hot that the metal elements are molten! Molten means that something is liquid from melting. The outer core is ever hotter than the mantle!! The outer core has temperatures starting from 4000 degrees Fahrenheit to 9000 degrees Fahrenheit! The elements that make up the OUTER CORE are: Iron, Nickel

17. The inner core elements Inner Core - All the other layers press down on the inner core. The pressure from all the other layers make the inner core solid even though this layer is the hottest layer. The temperature of the inner core reaches up to 9000 degrees Fahrenheit! The element that make up the INNER CORE is: Iron

18. The End BONUS: Find a pair or trio and answer this question: Have we ever seen part of the Mantle? Explain. © Copyright 2006. M. J. Krech. All rights reserved.