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  • 1. 3.1 The Changing Environment
  • 2.
    • Earth is about 4 billion years old
    • Humans about 500,000 years old
    • Change has always occurred
    • Most rapid changes, as a result of humans
  • 3. Changes in the Lithosphere
    • Earth’s crust is made of tectonic plates which shift and move – causing earthquakes, mountain-building
    • Weathering- the breaking down of rocks by weather and water
    • Erosion- broken down material is carried off
  • 4. Plate Tectonics
  • 5. Weathering
    • As you watch this clip- write down the forces that cause weathering.
  • 6. Erosion
    • Again, write down the forces that cause erosion.
  • 7. Changes in the Hydrosphere
    • As the land moves, this changes the oceans- these changes tend to be slow and steady
    • Other changes are cyclic:
    • Ice Ages
    • El Nino
  • 8. Ice Ages
    • Occur over millions of years
    • Lengthy cooling creates glaciers that grow from polar regions and extend over much of the Earth’s surface
    • As warm periods come, glaciers melt and retreat to polar areas: sea level rises
    • There have been at least 5 major ice ages; latest was 10-12 thousand years ago
    • Glaciers movements cause major affects on the land- most of northern North America has glaciated landscapes
    • What causes Ice Ages? Know one really knows- maybe wobbling of Earth’s axis
  • 9. Glaciers
  • 10. El Nino
    • Caused by warm, nutrient-poor water flowing along the coast of South America ( western coast); lasts for months instead of usual few weeks
    • Occurs near end of December ( El Nino means “the child”, as in the Christ child)
    • Climate( globally) is affected because of the warm water
    • Economics are affected- nutrient poor water means fewer fish, and fish is a major staple in these regions
  • 11. The Atmosphere Changes
    • Sunlight and Earth’s rotation affects both daily and seasonal changes
    • Before life formed- atmosphere was created by volcanic gases- H 2 O, CO 2 , sulfur gases
    • After life formed- O 2 was added ( photosynthesis)
    • Life cycles O 2 , CO 2 , N 2 , and water – they absorb these gases, then release them back to the atmosphere
    • Carbon particularly can be “stored” in living things- coal, fossil fuels, trees etc. Once these are burned the carbon is released back into the atmosphere (in form of CO 2 ) and absorbs heat - Greenhouse Effect
    • Humans have also altered the ozone content.
    • Natural events can also alter the atmosphere-
    • volcanic eruptions, forest fires