1. Warm Up #6 How are we able to date things like the age of rocks?
Why, despite the earth being approx. 4.6 billion years old, are we unable to find rocks older than 3.3 billion years old?
How do you think earthquakes work?
How do you think volcanoes work?
What are the three major types of rocks that exist on earth?

2. Plate Tectonics

3. The Rock Cycle
Igneous Rock – formed as magma (molten rock) cools and rises up
Sedimentary Rock – formed via compaction of various rocks, coming together in water
Metamorphic Rock – formed from heat and pressure of pre-existing rocks

4. Earth’s Evolution How is this Possible?

5. Why do the Plates move?
Convection Currents – uneven heating of Earth = shifting of asthenosphere
How wind works!
Subduction = cooler magma falling toward Earth’s core
Mid-Ocean Ridges = warmer magma rising to Earth’s surface

7. How are Rocks Shifting?
Plate Tectonics – movement of giant rock plates
Earthquakes, volcanoes, trenches, mountains, etc.
3 Types
Convergent – two plates move TOWARD each other
Divergent – two plates move AWAY from each other
Transform – two plates rub against each other in opposite directions

8. Where this is Happening
Review: Core, Mantle, Crust
In Mantle, two layers:
Lithosphere – top part of mantle/bottom of crust
Tectonic plates that move
Asthenosphere – bottom part of mantle
Where magma is found

9. How Divergent Plates Work
Plates move away
Magma flows in to fissure (hole between plates) and cools
Forms oceanic ridges, rift valleys, new sea floor (seas, oceans)
Atlantic, South Pacific, Indian Oceans

10. Oceanic Ridges & Rift Valleys

11. The Pacific Ocean is Shrinking!
newest
oldest

13. How Convergent Plates Work
Plates come together
One moves downward (Subduction Zone)
Trench forms, mountains, too
Magma pushed up
Volcanic eruption
Earthquakes
Pacific Ocean (Ring of Fire), South America (West), Himalayas
Subduction Zone

14. Result: Volcanoes
Volcanoes – opening on Earth’s crust for magma (lava) to be released
convergent, divergent and “hot spots”
Ring of Fire – Pacific Ocean
Divergent Plate boundaries
VERY active volcanic region

15. How Transform Plates Work: LA
Rub against each other
Fracture Zone
Similar to convergent
Except no sinking
Earthquakes triggered
Ex. San Andreas Fault

16. Will We Be an Island? San Andreas Fault: CA shifting northwest
CA = Pacific Plate
AZ = North American Plate
CA shifting northwest
AZ shifting southeast
33mm/year
In 100,000+ years:
CA = in Oregon/Wash.
Hipsters….

17. Quick Quiz # 3
What forms as a result of a convergent plate boundary? What are the differences and similarities between this and the result of a divergent plate boundary?
Why will a volcano not erupt in Southern California? Why are they so active in the Pacific Ocean?
How do sedimentary rocks form? Why are they found mostly on Earth’s surface, and NOT the outer core?