Across
- 3. a fossil copy of an organism made when a mold of the organism is filled with sediment or mineral deposits
- 4. relationship principle that states that the geologic feature which cuts another is the younger of the two features
- 6. the age of rocks and geologic features compared with other nearby rocks and features
- 7. a fossil representative of a species that existed on Earth for a short length of time, was abundant, and inhabited many locations
- 9. the preserved evidence of the activity of an organism
- 12. a surface where rock has eroded away, producing a break, or gap, in the rock record
- 16. a principle stating that geologic processes that occur today are similar to those that occurred in the past
- 18. a method used by geologists to fill in the missing gaps in an area's rock record by matching rocks and fossils from separate locations
- 19. the impression of an organism in a rock
Down
- 1. a piece of an older rock that becomes part of a new rock
- 2. atoms of the same element that have different numbers of neutrons
- 5. any method of determining the age of earth materials or objects of organic origin based on measurement of either short-lived radioactive elements or the amount of a long-lived radioactive element plus its decay product
- 6. the process by which an unstable element naturally changes into another element that is stable
- 8. the time required for half of the amount of a radioactive parent element to decay into a stable daughter element
- 10. scientist who studies fossils
- 11. the principle that in undisturbed rock layers, the oldest rocks are on the bottom
- 13. the fossilized carbon outline of an organism or part of an organism
- 14. the preserved remains or evidence of past living organisms
- 15. the idea that conditions or creatures on Earth change in quick, violent events
- 17. the numerical age, in years, of a rock or object