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Changes in the lithosphere

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

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