Geological Time Scale

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Across
  1. 3. many types of animals go extinct
  2. 4. fossils in which minerals are replace all of an organism
  3. 7. the number of years that have passed since a rock has formed
  4. 9. the time it takes for half of the radio active atoms to decay
  5. 11. animals with backbones
  6. 13. solid copy of the shape of an organism
  7. 14. lava that hardens on the surface and forms igneous rock
  8. 15. determines the relative ages of sedimentary rock layers
  9. 16. vertebrate that controls body temperature
  10. 17. part water life part land life
  11. 20. animals without backbones
  12. 23. a break in earth's crust
  13. 25. scientist who studies fossils
  14. 26. provide evidence of the activities of ancient organisms
  15. 27. balls of dust, gas, and ice that orbit the sun
Down
  1. 1. a widely distributed fossil in a short time
  2. 2. extremely thin coating of carbon on rock
  3. 5. preserved remains or traces of living things
  4. 6. record of the geological events and the evolution of the life forms as shown in the fossil record
  5. 8. igneous rock caused by magma
  6. 10. organisms that no longer exists
  7. 12. the particles released by elements
  8. 18. broken down eras
  9. 19. gap in the geological record
  10. 21. broken down eons
  11. 22. its age compared to the ages of rocks
  12. 24. hollow area of sediment in the shape of an organism