Across
- 3. is when the youngest layer cuts through other layers
- 4. theory is that older rocks are below the younger rocks
- 8. the time it takes for half of an isotope to decay
- 9. age uses fossils and isotopes to determine the rock's age in years
- 10. the age of dinosaurs
Down
- 1. A once-living life form that can be used to represent a period of time
- 2. age of when the continental plates formed
- 5. when the youngest rock is around the oldest
- 6. the extinction of dinosaurs
- 7. age dating determined by rock layers