1. The Earth Famous picture Famous picture Oblateness of 0.0034 (demo) Oblateness of 0.0034 (demo) Average density is ~5.5 g/cm 3 Average density is ~5.5 g/cm 3 Whereas surface rocks ~3… Whereas surface rocks ~3…

2. Seismology tells of interior Waves from earthquakes refracted at boundaries Waves from earthquakes refracted at boundaries Liquid and solid inner cores Liquid and solid inner cores Rotation of liquid core leads to … Rotation of liquid core leads to …

3. Magnetic Field Permanent magnet possible? Permanent magnet possible? Alternative: currents… Alternative: currents…

4. Magnetic Field “Dynamo” action of rotating liquid core “Dynamo” action of rotating liquid core Charged particles in liquid core move (and moving charges = a current) Charged particles in liquid core move (and moving charges = a current) Aurora Aurora

5. Interior structure Core heated in formation, kept hot from natural radioactivity Core heated in formation, kept hot from natural radioactivity Cools slower than smaller bodies like the Moon and Mercury (& babies) Cools slower than smaller bodies like the Moon and Mercury (& babies) Convection of lithosphere leads to seismic events and plate tectonics… Convection of lithosphere leads to seismic events and plate tectonics…

6. Plates of the Earth Action occurs along plate boundaries…

7. Volcanoes Mt. St. Helens…

8. Island Strings Hawaiian Islands How formed?

9. Hot Spots + Plate Motion xx xx

10. Earthquakes

11. Continental Drift If we back up…

12. Pangaea – 260 million years ago