Across
- 6. Remains of previous organisms that are used to date a layer's relative age
- 7. Rule that says the top is the newest, and the bottom is the oldest
- 9. Someone who studies the earth's crust
- 10. Another word for layers
Down
- 1. The time it takes for the radioactivity of an isotope to become half it's orignal amount
- 2. Someone who studies fossils on the the earth's crust
- 3. Specifically how old a layer is, based on the rate of radioactive decay
- 4. Remains of previous organisms
- 5. How old a layer is in regards to something else (not specific)
- 8. Determining how old a layer is (relative and/or absolute)