Index fossils

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Index fossils

  1. 1. Relative Age <ul><li>Age of a rock compared to the ages of other rocks </li></ul>
  2. 2. Absolute Age <ul><li>Number of years since the rock formed </li></ul>
  3. 3. Law of Superposition <ul><li>Scientists use to determine RELATIVE age of a rock </li></ul><ul><li>Youngest layer is always located on the top, oldest layer always located on the bottom </li></ul>
  4. 4. Law of Superposition Activity <ul><li>Rock layers T and C are the oldest </li></ul><ul><li>Each card must contain one common letter </li></ul><ul><li>Place cards in order as they might appear in a canyon </li></ul>
  5. 5. <ul><li>How do you know X is older than M? </li></ul><ul><li>Explain why D in the rock layer represented by DM is the same age as M </li></ul><ul><li>Explain why D in the rock layer OXD is older than D in the rock layer DM </li></ul>TC CGA AU UBN BN NO OXD DM
  6. 6. Index Fossils <ul><li>Fossils of widely distributed organisms that lived during only one short time period </li></ul>
  7. 7. Index Fossil?
  8. 8. Index Fossil?
  9. 9. How has the environment changed?
  10. 10. Determining Relative Age using fossil evidence <ul><li>Sequence the cards according to relative age </li></ul><ul><li>Keep in mind that extinction is forever </li></ul><ul><li>Layer M is the oldest </li></ul>
  11. 11. How’d you do? <ul><li>What clues did you use to help you determine the rock sequence? </li></ul><ul><li>Are any of the fossils good index fossils? Why? </li></ul>
  12. 12. Reflection page 42 <ul><li>If humans were to suddenly become extinct, do you think that we would be a good index fossil? Why or why not? </li></ul>

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