1. Earth’s Layers G 103

2. General Information -Iron,Oxyge, Silicon, & Magnesium - Deepest drill 12 km -Radius of Earth 6371 km - How do we know about the earth’s interior?

3. Moho Discontinuity Change in seismic velocity

5. Crust Continental crust - 8-75 km thickness - Upper crust composed of granitic rocks - Average density is about 2.7 g/cm 3 - Up to 4 billion years old Oceanic crust - 7 km thickness - Basaltic composition - Density about 3.0 g/cm 3 - Younger (180 million years or less) than the continental crust

6. Mantle Below crust to a depth of 2900 kilometers -Density of 3.4 g/cm -Peridotite -Upper & Lower -Flow?

7. Core -Iron and nickel -Density of 13 g/cm

8. Layers by Physical Properties Heat & Pressure Lithosphere Asthenosphere Outer Core Inner Core

9. Temperature & Pressure What Happens with Depth? Geothermal Gradient

10. Lithosphere Crust and uppermost mantle (about 100 km thick) Cool, rigid, solid

11. Asthenosphere Beneath the lithosphere Upper mantle To a depth of about 660 kilometers Soft, weak layer that is easily deformed

12. Lower Mantle 660–2900 km More rigid layer Rocks are very hot and capable of gradual flow.

13. Inner & Outer Core  Inner Core Sphere with a radius of 1216 km Behaves like a solid  Outer Core Liquid layer 2270 km thick Convective flow of metallic iron within generates Earth’s magnetic field