1. GEOL 4110 Advanced Earth Science For Teachers Jim Miller

2. Plate Tectonic Theory The Earth’s outer shell (lithosphere) is composed of rigid plates that are moving relative to one another.

3. Physical and Chemical Structure of the Earth Chemical Layers Physical Layers Lithosphere Compositional Components of the Lithosphere Continental Crust – ~62% SiO 2, low density rocks, “felsic” Oceanic Crust - ~ 48% SiO 2, high density rocks, “mafic” Lithospheric Mantle - ~ 40% SiO 2, very high density rocks, “ultramafic” Lithospheric Mantle

4. Plate Tectonics drives 2 Stages of Crust-making 1. Mantle partially melts to make ocean crust 2. Ocean crust melts to make continental crust

5. What moves the Plates? Slab Pull - densification of subducted plate pulls the plate into the mantle Mantle Push - Upwelling of the asthenospheric mantle pushes the plates apart Ridge Slide – Thermal upwelling at ridges causes plates to separate by sliding downhill (by gravity) Problem - we are not sure how the mantle is structured.

6. Types of Plate Boundaries

7. Divergent Plate Boundaries Mid-ocean Ridges Where Stage 1 Crust is Made

8. Youthful Oceanic Crust

9. Basalt – Rock Type of the Oceanic Crust Remember: Melting the mantle makes mafic magma!! Always

10. Continental Rifting The creation of new ocean basins

11. Continental Rifting and The Break-up of Pangea

12. Convergent Boundaries Making 2 nd Stage Crust Ancient Continental Crust

13. Convergent Boundaries- Where the Action Is!! Ocean- Continent Continent - Continent Ocean - Ocean Earthquakes Volcanoes

14. Mt. St. Helens May 18, 1980 Consequences of Convergence Explosive Volcanism

15. Consequences of Convergence Mountain Building and Rock Deformation

16. Consequences of Convergence - Earthquakes 1326 Aftershocks

17. OROGENESIS The Culmination of Convergence

18. San Francisco Earthquake April 18, 1906 Mag 7.8 Transform Boundaries

19. Mantle Hotspots Creation of overthickened oceanic crust

20. Famous Hotspots Hawaii Yellowstone? Iceland

21. The Grand Unifying Theory of the Earth