4th Grade-Ch. 9 Lesson 1 How does earth's surface wear away

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4th Grade-Ch. 9 Lesson 1 How does earth's surface wear away

  1. 1. Ch. 9 Lesson 1 How does Earth’s surface wear away?
  2. 2. <ul><li>natural features on Earth’s surface </li></ul><ul><li>mountains, plains, plateaus, peninsulas </li></ul>landforms
  3. 3. Along coasts, landforms such as peninsulas extend into the water.
  4. 4. weathering <ul><li>process that breaks down rocks in Earth's crust </li></ul>
  5. 5. <ul><li>examples of weathering </li></ul>
  6. 7. mechanical (physical) chemical 2 types of weathering
  7. 8. <ul><li>physical weathering - </li></ul><ul><li>no change in chemical composition--just broken into smaller pieces </li></ul>
  8. 9. causes of physical weathering:
  9. 10. 1. water
  10. 11. 2. ice
  11. 12. 3. temp. changes
  12. 13. 4. plant roots
  13. 15. Physical Weathering 02:39
  14. 16. chemical weathering <ul><li>rock broken into smaller pieces </li></ul><ul><li>material that makes up rock or soil changes </li></ul>
  15. 17. causes of chemical weathering:
  16. 18. <ul><li>acids in rainwater </li></ul>This photograph shows a small section of masonry from a church in northern France. The rock was originally a smooth pillar like structure forming part of the outside decoration of the building. Over the last hundred years or so, acidic rain water has constantly dripped onto the rock from a rain gutter several meters above it.
  17. 19. <ul><li>Carbon dioxide (CO 2) dissolves in rain water & creates carbonic acid  acid rain </li></ul><ul><li>Carbonic acid easily weathers limestone & marble </li></ul>
  18. 21. <ul><li>chemicals from plants </li></ul><ul><li>lichens grow on rocks -make weak acids that chemically weather rock </li></ul>Rock meets lichen YouTube video
  19. 22. <ul><li>oxidation= iron combines w/ oxygen & H 2 0 </li></ul><ul><li>makes rust </li></ul>
  20. 23. Oxidation turned these rocks in Nevada's Valley of Fire red.
  21. 24. Chemical Weathering [02:57]
  22. 25. Weathering Walk <ul><li>Find 3 places where weathering has occurred </li></ul>chemical Rusty AC chemical Rust Bench Physical Incline Trench in pit Physical Tree roots-cracking sidewalk Tree-sidewalk sidewalk physical or chemical appearance location

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