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Geologic Time

Geologic Time. Life Science Mr. P. Divisions of Geologic Time. Eras : large portions of time Periods : subdivision of an era. When does one begin and another end?. Scientists look at mass extinctions and the organisms that are present Mass Extinction: dying off of many species.

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Geologic Time

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  1. Geologic Time Life Science Mr. P

  2. Divisions of Geologic Time Eras: large portions of time Periods: subdivision of an era

  3. When does one begin and another end? Scientists look at mass extinctions and the organisms that are present Mass Extinction: dying off of many species

  4. Causes of Mass Extinction • Catastrophic Events: • Climate Change • Volcanoes • Asteroid Impacts • Disease • Many others…

  5. Dino Extinction • What killed the dinosaurs? • Asteroids? • Volcanoes? • Disease? • Earthquakes? • Something else?

  6. Asteroid It is now believed to have been an asteroid that killed the dinosaurs Why?

  7. Reasons for an asteroid 1) Asteroids have been hitting earth since it was formed 2) Asteroid impacts can cause worldwide destruction and block the sun with debris 3) There is evidence of an impact near the Gulf of Mexico!

  8. Impact Point

  9. After a mass extinction… After a mass extinction, new life is able to grow. This is because habitats (where plants and animals live) are left empty

  10. Precambrian Era Increased volcanic activity produced nitrogen and carbon dioxide gas, which created the atmosphere. This allowed life to develop First life forms: bacteria and invertebrates

  11. Paleozoic Era 600 million years ago Complex life suddenly appeared Life: Vertebrates, Invertebrates, and land plants Mass Extinction ended the era: 90% of all marine life and 70% of all life on land

  12. Mesozoic Era Time of the dinosaurs and flowering plants Mass extinction that killed off the dinosaurs ended the mesozoic era, giving rise to the mammals

  13. Cenozoic Era Era we are in now Rise of mammals and primates Humans evolved not long ago

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