Geologic Time Crossword Ishaan Brahma

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Across
  1. 3. rock layer formed when lava cools on the Earth's surface
  2. 5. a fossil that shows the activities of ancient organisms
  3. 9. fossil made by a extremely thin coating of carbon on rock
  4. 12. a person who studies fossils
  5. 15. a record of the geologic events in Earth's history
  6. 17. the process in which radioactive elements break down
  7. 18. a group of organisms that has completely died out
  8. 19. the exact age of a rock
  9. 21. widely distributed fossils of an organism the lived for a short time
  10. 23. a mold fossil that was filled in and turned into a stone replica of the organism
Down
  1. 1. parts that eras are split into
  2. 2. a crack in Earth's surface on which rocks move
  3. 4. A gap in the geologic record that shows where rock layers have been lost due to erosion
  4. 6. when rock layers are horizontal, each rock layer is older than the one above it
  5. 7. rock layer formed when magma hardens below the Earth's surface
  6. 8. three long units of time that only end with mass extinctions
  7. 10. type of fossil that is a hollow space in sediment in the shape of the organism
  8. 11. a type of fossil that is fully or partly replaced by minerals
  9. 13. the time it takes for half the atoms in a radioactive element to decay
  10. 14. the age of a rock in comparison to another rock
  11. 16. a collection of ice and dust that orbits the sun
  12. 20. how organisms change over long periods of time
  13. 22. a way that nature shows us the organisms that lived in the past