Final Review

Final Review - FINAL REVIEW Chapter 19. Earth- 4.6 billion...

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FINAL REVIEW Chapter 19. Earth- 4.6 billion years old Universe- 14 billion years old Different life forms in each strata. Youngest layer- top Oldest layer- bottom Major Extinction Events- defines the end of an era or period Cretaceous Extinction- occurred at boundary between cretaceous and tertiary periods. Extinction aided by impact of one or more giant asteroids. (end of dinosaurs) Permian Extinction- occurred at boundary between permian and triasic periods. 96% of all species on earth were wiped out Not all eras and periods are marked off by extinction. Example: Explosion in diversity of new life forms. Three domains Archaea- life populated entirely by microscopic, single-celled organisms, many of which live in “extreme” environments such as boiling hot vents on the ocean floor. Bacteria- single-celled microscopic creatures, the bacteria that are more familiar to us. Eukarya- most familiar- plants, animals, and fungi- along with protists. (protist kingdom has many single-celled water dwellers, but includes some large organisms auch as giant sea kelp.) How did life begin? “Accretion” process- ever-larger particles clumped together: cosmic dust to gravel, gravel to larger balls, larger balls to objects the size of tiny planets. Accretion (now called earth), periodically being slammed into by other large accretions (meteorites, comets, and proto-planets). One object being as large as Mars- result of its impact on earth: 100 million years after earth formed, may have been the creation of the moon. No oceans at this time. Earth was hot- covered in layer of molten rock. (atmosphere similar to Jupiter). Lightening storms, volcanic eruptions. Sun shined 20- 30% less bright. Two possibilities:
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Final Review - FINAL REVIEW Chapter 19. Earth- 4.6 billion...

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