Plate Tectonics

1. Plate Tectonics

2. Earth Structure Quick review • Earth is made up of four main layers; crust, mantle, outer core and inner core. • Crust- on the outside, very thin and hard. • Mantle- The largest part making up 2/3 of the earth. • Outer Core- Lies above the inner core and is thought to be composed of mostly molten metal. Liquid. • Inner Core- Hottest place on Earth. Solid iron. Thought to create magnetic field.

3. The Crust • What make up the earth’s crust? • What is the lithosphere? • Crust consists of many continental and oceanic plates that have slowly moved and changed positions on the globe throughout geologic time. • The rigid upper part of Earth’s mantle and crust. The location of our plates.

5. Plate Tectonics • What are plates? • What is plate tectonics? • The Earth is broken up into pieces of land which move slightly around the Earth. • Very slow- movement can take more than a year to move a few centimeters. • Pieces of the lithosphere that move around. • Each plate has a name • Fit together like jigsaw puzzles • Float on top of mantle similar to ice cubes in a bowl of water

6. Earth Plates

7. Alfred Wegener • He proposed that in the distant past, the Earth’s continents were all joined as a single landmass. • After putting all of Earth’s puzzle pieces together he named the land mass Pangaea.

9. Fossil Evidence

10. Plate tectonics • Plate Boundaries- • Fault- • The places where the edges of different plates meet • Plates- • Slide • Separate • Collide • Large fractures in rocks along which movement occurs.

11. How do Plates move? • Plate Movement • Sliding • Separating • Colliding • Plates slide along each other, earth quakes commonly occur from the built up pressure. • When plates move apart, new crust forms to fill the gap between plates. • Tremendous force causing large mountains to form.

12. Divergent Convergent Transform Three types of plate boundary

13. Divergent Boundaries • Spreading ridges • *As plates move apart new material is erupted to fill the gap

14. Divergent Boundaries

15. Iceland: An example of continental rifting • Iceland has a divergent plate boundary running through its middle

16. Convergent Boundaries • There are three styles of convergent plate boundaries • Continent-continent collision • Continent-oceanic crust collision • Ocean-ocean collision

17. Continent-Continent Collision • Forms mountains,e.g. European Alps, Himalayas

18. Himalayas

19. Continent-Oceanic Crust Collision • Called SUBDUCTION

20. Subduction • Oceanic lithosphere subducts underneath the continental lithosphere • Oceanic lithosphere heats and dehydrates as it subsides • The melt rises forming volcanism • E.g. The Andes

21. Ocean-Ocean Plate Collision • When two oceanic plates collide, one runs over the other which causes it to sink into the mantle forming a subduction zone. • The subducting plate is bent downward to form a very deep depression in the ocean floor called a trench. • The worlds deepest parts of the ocean are found along trenches. • E.g. The Mariana Trench is 11 km deep!

22. Transform Boundaries • Where plates slide past each other Above: View of the San Andreas transform fault