Unit 1

3. exact number of years the rock formed.
6. Instead of a land bridges idea, wegener was looking at the edges of continents and noticed that they looked similar.
8. the amount of time it takes for half of the radioactive atoms to decay.
9. huge sheets of ice called glaciers cover large parts of the earth.
10. a stars life expectancy is based on its.
12. As the universe began to cool protons and neutrons where formed.
18. at several different points in earths history, all of the continents have been located close to each other.

1. a star begins to run out of fuel the core shrinks and the outer parts expands.
2. A rocks age compared to the edges of other rocks around it.
4. Wisconsin episode 75,000 years ago.
5. This is how we can tell is an object is moving towards us or away from us.
7. The universe formed in a instant billions of years ago.
11. lighter elements join together to form heavier elements.
13. large divisions of time.
14. very large span of time.
15. large numbers of species disappearing in a short period of time.
16. smaller divisions of times.
17. typically small changes that occur slowly.