Plate Tectonics

1. Plate Tectonics the movement of Earth

2. Plate Tectonics • Tectonic plates: pieces of the Earth’s crust & upper mantle • Plate boundaries: places where plates meet

3. Plate Tectonics • Movement of plates creates forces that affect Earth’s surface at the plate boundaries and causes them to move. • Plates move in 3 ways: • 1. slide past each other • 2. move apart (divergent) • 3. collide (convergent)

4. Transform Fault Boundaries • Faults form when plates slide past each other • A fault is a large crack in rocks that can break • EARTHQUAKES can happen along fault lines

6. San Andreas Fault, CA

7. Plates move apart b/c of pulling forces (tension) that act in opposite directions. New crust forms in the gaps where plates pull apart. Form mid ocean ridges (in oceans), and rift valleys (on continents) Divergent Plates

8. Divergent Boundaries • Boundary between two plates that are moving apart or rifting   • RIFTING causesSEAFLOOR SPREADING

9. Divergent Plate Movement: Seafloor Spreading • the movement of two oceanic plates away from each other (at a divergent plate boundary), which results in the formation of new oceanic crust (from magma that comes from within the Earth's mantle) along a mid-ocean ridge. • Ocean floor spreading was first suggested by Harry Hess and Robert Dietz in the 1960's.

11. Features of Divergent Boundaries • Mid-ocean ridges

12. Features of Divergent Boundaries • Rift valleys Quilotoa, Ecuador

13. Features of Divergent Boundaries • Fissure volcanoes Hawaii, USA

14. a divergent tectonic plate boundary located along the floor of the Atlantic Ocean the longest mountain range in the world. separates the Eurasian Plate and North American Plate and the African Plate from the South American Plate Mid-Atlantic Ridge

18. Divergent Plates Bridge between continents in Reykjanes peninsula, southwest Iceland across the Alfagja rift valley, the boundary of the Eurasian and North American continental tectonic plates.

19. Oceanic Ridges

20. When plates collide, different things can happen (depends on the density of the plates involved). There can be: continental-continental collisions, oceanic-oceanic collisions & continental-oceanic collisions Convergent Plates

21. Continental-Continental Collisions • Forms a mountain range

23. Oceanic-Continental Collisions • Forms a trench and volcanic arc

24. Andes Mountains, South America

25. Oceanic-Oceanic Collisions • Forms an island arc

26. Aleutian Islands, Alaska

29. When one plate plate sinks underneath another plate. The denser plate sinks underneath & into the mantle. Subduction Zones

30. Fold • When rocks bend due to force.

31. Fold: When rocks bend • Anticline (Upward) • Syncline (Downward)

32. Anticline

33. Syncline

34. the circulation of heat A theory explaining why the plates move. Theory says plates move b/c the mantle material is being circulated b/c of the difference in densities in the mantle. Convection