1. Structure of the Earth

2. Layers • Solid Inner Core • Molten Outer Core • Mesosphere • Asthenosphere • Lithosphere

3. 1. Solid Inner Core • Dense, iron-rich material at very high temperatures and pressures probably of the order of 7,000° F (4,800° C) and at 3.5 million atmospheres.

4. 2. Molten Outer Core • Dense, iron-rich material in a molten state, at temperatures of the order of 7,000° F (3,900°C) and pressures of 1.5 million atmospheres. • Swirling movements of material in this layer generate Earth’s changing magnetic field.

5. 3. Mesosphere • Rigid lower mantle. Moderately hot, moderately dense rock rich in magnesium and iron silicates. Temperature probably about 5,400° F (3,000° C).

6. 4. Asthenosphere • Plastic upper mantle. Similar in composition to mesosphere, but less dense and less hot 2,700° F (1,500° C). The material in this layer is a slow moving liquid. • Convection currents generate slow-swirling movements in this layer that cause lithospheric plates to move across the Earth’s surface.

7. 5. Lithosphere • Rigid upper mantle and Earth’s crust combined to form lithospheric plates that float on the asthenosphere.

8. Thickness of Earth’s Layers