Earth's History Crossword Puzzle

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Across
  1. 3. Fossil that forms when organic material is pressed between layers of rock
  2. 5. fossilized piece of evidence of an organism's activity
  3. 11. subdivision of an era
  4. 13. Method of determining the exact age using radioactive elements
  5. 14. fossil that forms when minerals solidify into the rock around the shape of the original organism
  6. 15. subdivision of an eon
  7. 16. Law stating younger rocks are toward the top and older toward the bottom
  8. 18. system of time measurement involving the formation of and changes to Earth
Down
  1. 1. The branch of science involving physical composition and history of Earth
  2. 2. information provided by all of the discovered fossils through earths history
  3. 4. when a species completely dies out
  4. 6. Determining the age of a rock using surrounding evidence
  5. 7. Common fossil found from a specific time used to help find the age of other formations
  6. 8. subdivision of a period (shortest division)
  7. 9. Fossil that forms when a mold is filled with sediment and hardens into the shape of that organism
  8. 10. usually referred to as the longest division of time
  9. 12. Preserved organism in a petrified rock
  10. 17. Fossil that forms when organic material is trapped in ice, rock, amber or tar