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