Across
- 3. Amount of time it takes for half an isotope to decay
- 5. Estimate of how old something is
- 7. Fossils that are used for dating
- 8. relating to the period before written records
- 9. New layers of rock on old layers
- 10. States that if the rock fragments are in another rock, the rock is older
Down
- 1. that if a fault cuts through a rock it is younger than the rock
- 2. Representation of time based on the rock record of earth
- 4. Preserved remains of something
- 6. Exact age of something