1. The earth’s structure

2. Earth’s Internal Structure: Compositional Layers

3. Crust the outermost solid shell of a rocky planet  Continental crust  thick (10-70km) - buoyant (less dense than oceanic crust) - mostly old  Oceanic crust  about 25 miles (32 kilometers) thick  - thin (~7 km) - dense (sinks under continental crust) - young

4. The Lithosphere The crust and the upper layer of the mantle together

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

6. Mantle layer of the earth between the crust and the core  Upper mantle  Lower mantle  The Asthenosphere  Largest layer  Convections currents

7. The Asthenosphere the semi-rigid part of the middle mantle  flows like hot asphalt under a heavy weight.

8. Convection Currents  caused by the very hot material at the deepest part of the mantle rising, then cooling and sinking again  The middle mantle "flows" because of convection currents.

9. The Outer Core composed of the melted metals nickel and iron.

10. The Inner Core 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.

11. Elements in the crust