Across
- 3. The “calendar” for events in Earth history
- 6. when species vanish much faster than they are replaced.
- 9. a method that provides objective age estimates for carbon-based materials that originated from living organisms
- 12. determine which things are older or younger based on their relationships
- 13. the absolute age dating method is a method of measuring how old a natural material is in years.
- 14. the fossil remains of an organism that lived in a particular geologic age
- 16. geological records of the activities and behaviors of past life.
- 18. the largest unit of time for the geologic time scale
- 19. when an older rock formation has been deformed
Down
- 1. Material filling in a cavity left by a organism that has dissolved away
- 2. The period of time extending from about 4.6 billion years ago elephant
- 4. The second longest portions of geological time
- 5. a method of establishing how old something is
- 7. an atom of a radioactive elements which has unstable nucleus breaks down, or decay.
- 8. what is used to determine the relative ages of rock strata, or layers.
- 10. microscopic fungi that live on plant or animal matter
- 11. the time required for half of something to undergo a process
- 15. the second smallest geochronologic unit, between a period and an age
- 17. the basic unit of geologic time