PLATE TECTONICS

1. PLATE TECTONICS

2. QUICK REVIEW: EARTH’S STRUCTURE CRUST MANTLE CORE

3. QUICK REVIEW: EARTH’S STRUCTURE CRUST: Top layer, rocky MANTLE: middle, Hot, rock & metal CORE: innermost, Very hot, very dense Iron & Nickel Partly liquid

4. NEW INFO: EARTH’S STRUCTURE TECTONIC PLATES – sections of the crust and upper mantle that are stuck together TECTONIC PLATES – “float” on top of the rest of the mantle and are slowly moving (a few centimeters per year)

5. 7 major plates on the Earth-the African, North American, South American, Eurasian, Australian, Antarctic, and Pacific plates + several smaller plates

6. THE EARTH’S TECTONIC PLATES

7. The place where the two plates meet is called a plate boundary There are 3 TYPES of Plate Boundaries.

8. THE EARTH’S TECTONIC PLATES: 3 Types of Boundaries: Divergent Convergent Transform

9. Convergent boundaries Occur when plates crash into each other Example: Indian Plate is crashing into Eurasian Plate

11. Subduction occurs at Convergent Boundaries • When one plate slides underneath another • Crust (solid) melts back into magma (liquid)

12. Ring of Fire - Japan • Sits where Philippine plate and Pacific plate are subducting under Eurasian plate • Feel earth tremors every few weeks • Lots of earthquakes, volcanoes and tsunamis (tidal waves) • 2011 Tsunami in Japan caused by underwater earthquake

13. Ring of Fire

15. Divergent boundaries Occur when plates move apart as new rock is pushed up from mantle Sea-floor Spreading

16. Mid-Atlantic Ridge is an example of a divergent boundary • Under Atlantic ocean • South American Plate is pulling away from African Plate • Magma (liquid) comes up from mantle and cools to form new crust (solid rock) • Volcanic mountains form deep underwater • Extra heat at great depths provides home to many strange animals

22. So, old crust subducts and melts into magma at Convergent Boundaries And, new crust is formed from cooling magma at Divergent Boundaries

23. Transform Boundaries Places where plates slide past each other are called transform boundaries

24. Transform Boundaries • San Andreas Fault in California • 5 Major Earthquakes in past 20 years!

25. Loma Prieta Earthquake 1989

26. WHAT HAPPENS AT BOUNDARIES? MOUNTAINS – at convergent boundaries – one of the plates is pushed upwards and forms Mountain ranges! EARTHQUAKES – Plates are giant slabs of rock pushing on each other. They do not glide by smoothly! Sometimes they build up huge amount of energy and then slip violently – an Earthquake! VOLCANOS – at convergent boundaries – one plate subducts and the pressure melts it! The newly formed liquid rock (magma) can be pushed to the surface – a Volcano!. At Divergent boundaries, magma is always flowing out – a slow stead oozing volcano! TSUNAMI– when earthquakes occur under water – they can trigger huge tidal waves - Tsunamis

27. WHAT HAPPENS AT BOUNDARIES? So, even thought he plates are only moving a few centimeters per year – that much Earth moving at all has a lot of energy and can release it in Very dramatic ways

28. Tidal wave caused by underwater earthquake

29. types of boundaries

30. WHAT HAPPENS AT BOUNDARIES? HEY WAIT! IF ALL THE PLATES ARE MOVING DOES THAT MEAN THE CONTINENTS ARE MOVING TO? DO NOT TRY TO COPY PICTURES ON NEXT SLIDES – BUT DO TAKE SOME GENERAL NOTES

31. THE EARTH’S PLATES TODAY

32. THE EARTH’S PLATES30 MILLION YEARS AGO

33. THE EARTH’S PLATES65 MILLION YEARS AGO

34. THE EARTH’S PLATES140 MILLION YEARS AGO

35. THE EARTH’S PLATES200 MILLION YEARS AGO

36. This “super-continent” was called Pangaea

37. THE EARTH’S PLATES100 MILLION YEARS IN FUTURE?

38. ACTIVITY • Plate tectonics puzzle