1. Plate Tectonics

2. Last 30 Days Earthquakes

3. Physical Features

4. Last 30 Days Earthquakes with Plate Boundaries

5. Earth’s Structure

6. Earth’s Layers
Core:
Inner Core: Center of the earth, solid ball of metal (Nickel and Iron), hottest layer
Outer Core: Liquid layer that surrounds the solid inner core, mostly Iron, some Nickel, causes the earth’s magnetic field
Mantle: Largest layer (84% of Earth), “plastic like fluid” (pliable), made of lighter elements
Crust: Hard outermost layer, made up of continental and oceanic crust
Lithosphere: Made up of upper mantle and crust, divided into tectonic plates

7. Tectonic Plates

8. Do the plates move?
Alfred Wegener (1910) noticed the shape of the continents fit together like puzzle pieces.
Evidence:
Fossils and mountain ranges on opposite sides of oceans
He couldn’t explain how the continents moved

9. New evidence Age of oceanic crust Magnetic alignment
Since then, scientists have discovered the mechanism that drives the plate movements:
Convection

10. How does a lava lamp work? Convection current:
The rising and sinking movement of a liquid or gas (but NOT a solid) due to changes in density
Warm materials are less dense
Cool materials are more dense

11. Plate Movement

12. Types of Crust Oceanic Crust Continental Crust Plate Boundary
Made of basalt
Thinner
More dense
Continental Crust
Made of granite
Thicker
Less dense
Plate Boundary
Where two tectonic plates meet
Convergent
When plates come together
Divergent
When plates move apart
Subduction
When the more dense plate turns downward and sinks into the mantle

13. Plate Boundary Types Convergent Divergent Transform
Where two plates move towards each other (collision)
Divergent
Where two plates move away from each other
Transform
Where two plates grind past each other

14. Convergent Boundaries
Oceanic-Oceanic
Older, colder crust subducts under the other oceanic crust
Melting of the subducted crust occurs and magma rises, forming a volcano (island arc)
Example: Japan, New Zealand, Aleutian Islands

15. Convergent Boundaries
Oceanic-Continental
Oceanic crust ALWAYS subducts under continental crust (more dense)
Melting of the subducted crust occurs and magma rises, forming a volcano
Example: Andes Mountains, Cascade Mountains

16. Convergent Boundaries
Continental-Continental
Continental crust is buoyant, so neither plate subducts
The crust thickens, forming mountain ranges and high plateaus on both sides of the mountains
Intense pressure and heat cause metamorphic rocks to form within the thickened crust
Example: Himalayan Mountains

17. Divergent Boundaries
Two plates are moving away from each other in opposite directions 
Oceanic Divergent Boundary
Magma rises and erupts from long cracks called Mid-Ocean Ridges
New crust forms along ridges and older crust moves outward towards continents
Example: Mid-Atlantic Ridge

18. Divergent Boundaries Continental
A convection current under continental crust (sometimes a hotspot) causes spreading
A Rift Valley forms
Spreading continues, seawater enters
Ridge continues spreading, ocean forms
Example: Red Sea, African Rift Valley

19. Transform Boundaries Where plates are sliding past each other
Lithosphere is neither created nor destroyed
Examples: San Andreas, most transform boundaries occur in mid-ocean ridges where spreading rates are not the same

20. Faults Fault: a fracture in the Earth’s crust Foot wall Hanging wall
Each type of plate boundary is associated with a type of fault:
Convergent ---→ Thrust/Reverse Faults
Divergent ---→ Normal Faults
Transform ---→ Strike Slip

21. Thrust/Reverse Faults
Compression stress
Associated with Convergent boundaries
Hanging wall moves up, foot wall moves down
When movement along a fault is the reverse of what you would expect with normal gravity we call them reverse faults!
Examples: Himalayan Mountains

22. Normal Faults Tension (extension) stress
Associated with Divergent boundaries
Hanging wall moves down, foot wall moves up
When movement along a fault is the normally what you would expect with normal gravity we call them normal faults!
Examples: Wasatch Fault

23. Strike Slip Sheering Stress Associated with Transform boundaries
Slip past each other with little up and down motion
Examples: San Andreas, zig zags in Mid-ocean Ridges
Strike Slip Fault