Across
- 5. a time where the earth's temp drops and ice covers the earth
- 9. where scientists try to find out the order in witch events, happened
- 10. came up with the Theory of plate tectonics,l, and continental drift.
- 12. The earth warming due to green house gasses and human activity
- 15. a process that creates new atomic nuclei
- 17. when multiple species of animal dies, and within the same time period.
Down
- 1. the numeric age of rocks and fossil
- 2. the life of atomic nucli
- 3. used to describe the mass of a start because it changes over time.
- 4. when the Continets move and run into one another.
- 6. describes how star wavelengths become shorter and longer
- 7. A theory that everything in the universe came into existence at the same time within an explosion.
- 8. a process where atoms fuse together
- 11. can be used to describe any unit in time no matter how big or small
- 13. glaciers include the Wisconson and Illinois ice ages
- 14. a period in time that is historically undefined
- 16. the longest unit in time
- 18. when a star runs out of Hydrogen fuel