Geologic Time - Earth Science Class

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Across
  1. 2. subdivided periods
  2. 5. a fragment of a space rock that has hit the ground
  3. 8. most recent epoch began 10,000 years ago
  4. 12. subdivided eras
  5. 13. the dying out of species of living things
  6. 15. a kind of dating that uses radioactive elements to put more precise dates on rocks and other materials
  7. 16. subdivided eons
  8. 18. a proposed epoch that highlights the impact humans have had on Earth; "The Age of Man"
Down
  1. 1. a kind of dating that looks at rock layers in relation to each other
  2. 3. era oldest in Phanerozoic eon
  3. 4. name given for the first 3 eons of Earth's history that make up about 80% of Geologic Time
  4. 6. a large space rock
  5. 7. one of the three major rock groups; they can contain fossils
  6. 9. era youngest in Phanerozoic eon
  7. 10. rock layers
  8. 11. the preserved remains or evidence of past living organisms
  9. 13. longest unit of geologic time
  10. 14. era middle in Phanerozoic eon
  11. 17. land vertebrate with legs directly below hips; lived in the Mesozoic Era