Chapter 2 Section 3 Internal Forces Shaping the Earth

1. Chapter 2 Section 3Internal 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

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