Across
- 3. any feature that cuts across a sequence of rocks
- 5. help recognise a period of time
- 7. different types of rock
- 9. based on either fossils or radioactive decay of specific isotopes
- 10. Time Scale a fossil used to identify the age of that rock layer.
Down
- 1. In an undisturbed sequence of rocks, the oldest rocks are in the bottom and the youngest of the top
- 2. radioactive isotopes of some elements decay at a known rate into daughter products
- 4. is an element
- 6. fossil is used to find the age of a rock layer
- 8. any rock or fragment that included inside of another rock