1. Plate Tectonics
The Earth is broken into 20 or so lithospheric plates which are “riding” on the hotter asthenosphere

2. Types of Plates Ocean (made of basalt and thin but dense)
Continental (thick but less dense)

3. 94% of earthquakes occur because of friction and movement along plate boundaries

4. Types of Boundaries Convergent: coming together
Divergent: moving apart
Transform (sliding): moving past one another

6. Transform Boundaries Slide past one another
Most famous is the San Andreas fault

7. Divergent Boundaries
Ocean ridges--lava erupts creating new ocean floor--pushing plates apart

8. Sea Floor Spreading
Divergent boundaries, or ocean ridges result in new sea floor…”sea-floor spreading.”

9. Convergent Boundaries
THREE types
ocean-ocean
continent-continent
ocean-continent

10. Ocean-Continent Ocean crust is denser and subducts
Plate melts…volcanic mountain range
Earthquakes
Trench

11. Ocean-Ocean Older plate subducts Earthquakes Trench
Volcanic island arc

12. Continent-Continent HUGE mountains Earthquakes
No subduction, so no volcanoes

14. Magnetic Reversals
Match on either side of ridge: Supports sea-floor spreading

15. Deep Sea Drilling
Rocks nearest the ridge are youngest…older as distance increases
Match on either side of the ridge