1. Plate Tectonics

2. Continental Drift Alfred Wegener German polar researcher, and meteorologist. hypothesized that the continents were slowly drifting around the Earth. His hypothesis was controversial and not widely accepted until the 1950s, when numerous discoveries such as palaeomagnetism provided strong support for continental drift, and thereby a substantial basis for today's model of Plate tectonics

3. Pangaea the super continent approx. 250,000,000

4. Evidence: Shorelines appear to match (like pieces of a puzzle)

5. Matching rock types and structures

6. Evidence: Matching fossils on different continents

7. Ancient climates Large grooves Carved by glaciers Are found in Tropical areas

8. Large coal fields of N America and Russia were once at the equator

9. http://www.ucmp.berkeley.edu/geology/tecall 1_4.movwww.ucmp.berkeley.edu/geology/tecall 1_4.mov

11. Rejecting the Hypothesis No way to explain the mechanism that would be able to move whole continents about in the ocean. After WWII there was a surge In advanced technology used To advance scientific research. Extensive studies of the Ocean floor revealed Much about the Layers of the Earth Mafic basalt Felsic granite

12. Plate Tectonics Major discoveries In science & technology Allow scientists to Develop the Theory Of Plate Tectonics The Earth’s surface is divided into large plates That move about on the “plastic” asthenosphere

13. What makes the plates move Radioactivity- Heat energy from decaying radioactive elements Uneven heat in the Mantle causes CONVECTION CURRENTS

14. The solid lithosphere is broken into pieces and moves on top of the “weak” or “plastic” asthenosphere. This movement explains the cause of earthquakes, volcanoes, oceanic trenche s, mountain range formation, and many other geologic phenomenon.

15. Types of Plate Boundaries Divergent Boundary Lithospheric plates move apart Seafloor spreading and A Mid-Ocean ridge KEY Words: rift, ridge

16. Youngest rock is found near the ridge, oldest rock is near the continents Older rock Younger rock

17. Locations: Red Sea Great African Rift Zone Mid-Atlantic Ridge

18. Africa’s Great Rift Valley A divergent boundary Can you find it on a map?

19. Convergent Boundaries Ocean – Continental Boundary Key Words: Subduction trench Locations: Andes Mt.s Cascade Mt.s (can you find these on a map?

20. Convergent – oceanic- oceanic Key Words: Subduction, Trench Island arc Locations: Japan Philippines Indonesia Aleutian islands (Find these on a map) What is formed “behind” The string of islands?

21. Continental – Continental Convergent Locations: Himilayas Alps (find these on a map) Note: NO subduction zone, NO trench. Mt.s are folded upward.

22. Transform Plate Boundary Location: The San Andreas Fault (find on a map)

23. Evidence - Polar Wandering found in the layers of rocks

24. The following slides show details of more evidence gathered to support Plate Tectonic Theory

25. Evidence: Magnetic Reversal http://jeffcoweb.jeffco.k12.co.us/isu/science/9earth/maganimation.html The metallic minerals in The rocks are a “record” Of the direction of the poles At the time of crystalization

27. Evidence: Seafloor Spreading – each “layer” shows different ages of the rock and demonstrates When there is a polar reversal. (Like a horizontal version of a drill core sample of the deep ocean)

28. Earthquake Patterns When plotting the locations of earthquakes around the world.. They align with Plate boundaries. ( all have earthquakes, but not all boundaries have volcanoes, only boundaries with a subduction zone)

29. Ocean Floor Drilling

30. Hot Spots – unusual concentration of heat in the mantle Creates so much heat energy it breaks through the lithosphere In the middle of a plate.

31. Intraplate Hot Spots: Hawaiian islands The plate moves but the hot spot stays in place

32. Intraplate Hot Spot: Yellowstone National Park

33. Unusual Hot Spot on a plate boundary

34. Which type of boundary has upward convective movement? Which type of boundary does downward convective movement occur? What type of plate boundary is there no destruction of the earth’s lithosphere? Review: