Across
- 2. The age of a geologic phenomenon measured in present Earth years, rather than its age relative to other geologic phenomena
- 5. the process by which an unstable atomic nucleus loses energy by radiation
- 7. the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock
- 8. the approximate age of a specific rock layer
- 9. a scientific method that can accurately determine the age of organic materials as old as approximately 60,000 years
Down
- 1. method of age determination that makes use of the radioactive decay of uranium
- 3. one of the principles of geology scientists use to determine the relative ages of rock strata, or layers
- 4. the time it takes for one-half of a particular radioactive isotope in a sample to decay
- 6. divides up the history of the earth based on life-forms that have existed during specific times since the creation of the planet