1. Chapter 2 Section 3 Internal Forces Shaping the Earth
Plate Tectonics
Earth’s surface made up of tectonic plates
Theory Continental Drift: 1 Super continent Pangaea pulled apart
Plate movement works four different ways

2. PLATE MOVEMENT & BOUNDARIES
Divergent boundaries – Hot magma rises up & plates move apart (Spread Horizontally)
Example: Saudi Arabia & Egypt are part of Great Rift Valley, crust is pulling apart
Red Sea is becoming wider and wider

3. PLATE MOVEMENT & BOUNDARIES
Convergent Subduction: Oceanic plate & continental plates crash one is forced under causes volcanic zones
Convergent Collision: Two continental plates collide, plate buckle & fold ; forms mountain ridges
Example: Himalaya Mountains caused by India plate colliding into Asian continent

4. PLATE MOVEMENT & BOUNDARIES
Transform Plate – plates slide past one another faults/fractures appear on crust; earthquakes happen along the boundaries.
*Does not create new landforms

5. Earthquakes!
Caused by transform faults
- Measured by a seismograph

6. Chapter 2 Section 3 Internal Forces Shaping the Earth
Epicenter: focal point of earthquake, 95% in a fault zones
- Earthquakes trigger landslides, fires, collapsed buildings, aftershocks, human loss & Tsunamis

7. Chapter 2 Section 3 Internal Forces Shaping the Earth
Measured on the Richter Scale, uses numbers from 1 to 10 to represent energy released

8. - Earthquakes in the Pacific Ocean often lead to tsunamis, 50 to 100 ft. tall waves that can travel up to 450 mph

9. Volcanoes! Caused by convergent faults and subduction
- Thinner plate is pushed under thicker plate, hits the mantle and melts, rises up as lava (called magma when underground)

10. Chapter 2 Section 3 Internal Forces Shaping the Earth
Volcanic eruptions are not predictable; remain inactive for a long time, then suddenly become active

11. Chapter 2 Section 3 Internal Forces Shaping the Earth
Largest concentration of volcanoes found around the RING OF FIRE on the margins of the Pacific Ocean
Eight major plates meet in this area

12. Chapter 2 Section 3 Internal Forces Shaping the Earth
- Volcanoes also found over hot spots, areas not on plate boundaries where the plate is thin and magma rises up and reaches the surface (Example – Hawaiian Islands)

13. World Geography
Chapter 2
Section 4

14. External Forces Shaping the Earth
Weathering – Processes that break down rock into sand, silt or sediment
- Mechanical weathering – the physical breakup of rock by frost wedging or roots

16. Chapter 2 Section 4 External Forces Shaping the Earth
Chemical weathering – rock is dissolved as a result of chemical breakdown
Examples: acid rain and rust

17. Chapter 2 Section 4 External Forces Shaping the Earth
Erosion – occurs when material is moved by the wind, water, ice, or gravity
Water causes abrasion as it washes past and causes rocks to collide
Wind erosion works the same way
- Glaciers cause lots of erosion through glaciation as they move down from mountains

18. Any Questions
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