Earth's Structure

In a previous post of mine named Onion Earth I explained how the earth has a layered structure somewhat resembling an onion. The earth has several layers such as crust, mantle core, asthenosphere, mesosphere etc. Some of these layers overlap each other and thus can create confusion. This problem could be avoided by classifying these layers in two ways, one based on the Chemical composition and the other based on the physical properties.

Based on Chemical composition, three layers are identified.
1. Crust  -  Abundant in elements Si , O, Al, Mg, and Fe
2. Mantle  -  Mainly Fe, Mg, Si
3. Core  -  Ni and Fe alloy

Based on the physical properties five layers are identified.
1. Lithosphere  -  Rigid outer shell. Comprises of the crust and uppermost mantle
2. Asthenoshpere  -  Shows plastic behavior. Lithosphere "floats" on this layer. 5% of rocks in this layer is molten
3. Mesosphere  -  Extends from about 300km to 2000km beneath the surface. Solid
4. Outer Core  -  Molten. Rotates around the inner core and produces the earths magnetic field
5. Inner Core  -  Extreme pressure causes it to stay solid despite the high temperatures

Source : http://www.tulane.edu/~sanelson/images/earthint.gif