6th Grade Geo Time Scale

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Across
  1. 4. cavity left by deceased organisms body
  2. 5. example of a trace fossil
  3. 8. rate of radioactive decay
  4. 9. studies Earth
  5. 10. First geological period of the Paleozoic Era
  6. 14. extinct marine arthropod
  7. 15. Period of First Dinosaurs
  8. 17. Earth Science Teacher
  9. 18. preserved remains, impression, or trace of any once-living thing
  10. 20. the study of rock layers
  11. 22. Top Jurassic Predator
  12. 25. many organisms die
  13. 26. the world's first true vertebrates
  14. 27. covered entire continents during ice ages
Down
  1. 1. hazard to ancient organisms
  2. 2. Layers of Rock
  3. 3. Ruled after birds
  4. 5. 4.6 _____ years
  5. 6. burial condition for fossil formation
  6. 7. rock where most fossils are found
  7. 11. large extinct marine reptile
  8. 12. studies prehistoric life
  9. 13. Ruled after Dinosaurs
  10. 16. many layers of this build glaciers
  11. 19. Organism with no spine
  12. 21. lives part on land part in water
  13. 23. The most recent Super-continent
  14. 24. dating rock by comparison of known layers