Geologic Time Review

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Across
  1. 2. ________ _______ extinction, Caused by an asteroid about 7.5 miles across which impacted in the Gulf of Mexico at 45,000 miles an hour
  2. 4. _______ ________ extinction, 96% of all marine life goes extinct (taking 4-8 million years to recover), caused by volcanic event
  3. 6. section of time10 millions years
  4. 9. the longest section of time, 1 billion years
  5. 10. _______ ________ extinction, Earth warmed up by about 5-11℉, triggered by the release of greenhouses gases from a volcanic location
  6. 11. during the ______________ extinction, Oxygen levels dropped in the oceans, killing conodonts, ancient shelled relatives of squids and octopuses, and sponges
  7. 13. the earth is 4.6 ______ years old
  8. 14. what is the current eon?
Down
  1. 1. era with the cambrian explosion,leads to ocean life forms moving to land
  2. 3. during the ______________ extinction, an ice age began which locked up massive amounts of freshwater in ice, triggering an extinction event
  3. 5. age of the dinosaurs, had a humid/tropical climate
  4. 7. section of time, hundreds of millions of years
  5. 8. era that humans appear, continents reach their modern locations
  6. 12. section of time, about 3 million years