Earth’s History Reading Questions Integrated Science Name: Use pages 512-532 to answer the following questions. Period: 1. How old is the Earth? ___________________ 2. What percent of Earth’s history does the Precambrian take up? ___________________ 3. Why are very few fossils left from the Precambrian? 4. How do scientists believe Earth formed from space? 5. Page 515 details events in the formation of Earth. Describe them: a. initial formation b. melting c. bombarding d. volcanic activity 6. What three main gases was the early atmosphere made of? Which gas was absent? 7. How were the oceans formed? 8. When did oxygen first appear in the atmosphere and what “creature” created it? 9. The most common Precambrian fossils are ____________________ which are distinctively layered _________________ or columns of _________________ carbonate. 10. What three eras followed the Precambrian? Complete the following table: Periods with this era Cenozoic Mesozoic Paleozoic How long it lasted What occurred to life What occurred to land Major Animals