earth history vocab

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Across
  1. 1. very large division of geologic time; usually referred to as the longest division of time
  2. 3. refers to the information provided by all of the discovered fossils throughout earth's history
  3. 4. subdivision of an era
  4. 6. subdivision of a period; shortest division of geologic time
  5. 9. fossil that forms when a mold is filled with sediment and hardens into the shape of that organism
  6. 10. states that younger rock is found above older rock when comparing sedimentary rock layers
  7. 11. remains or impression of an organism preserved in petrified rock
  8. 13. the system of time measurement involving the formation of and changed to earth
  9. 15. fossil that forms when organic material is pressed between layers of rock
  10. 16. the branch of science involving the physical composition and history of earth
Down
  1. 1. occurs when a species (organism) dies out and no longer lives on the planet
  2. 2. fossil that forms when organic material is trapped in ice, rock, amber or tar
  3. 5. a fossilized piece of evidence of an organism's activity (footprint)
  4. 7. method of determining the age based on the surrounding evidence
  5. 8. a common fossil found in many areas from a specific time; used to help identify the age of other formations
  6. 12. fossil that forms when minerals solidify into rock around the shape of the original organism leaving a cavity behind
  7. 14. subdivision of an eon (paleozoic, mesozoic, cenozoic)