Historical Geology (GEOL102) - Exam 3 Review Crossword

12345678910111213141516171819202122
Across
  1. 1. The primary element in the present-day atmosphere
  2. 3. Oxygen levels INCREASED or DECREASED during the Proterozoic (pick one)
  3. 5. The oldest rocks on Earth, found in Canada (2 words)
  4. 7. Block of geologic time, during which continental crust formed
  5. 11. Largest chunk (88%) of geologic time
  6. 12. Unit of heredity, found in pairs and control traits
  7. 15. Early Proterozoic landmass that contained North America
  8. 17. Type of bird used by Darwin to demonstrate ideas of natural selection
  9. 20. The process by which life was able to arise on Earth
  10. 22. One of the two requirements for “life”
Down
  1. 2. Type of rock formations characterized by lower volcanic/metamorphic rocks, topped by sedimentary rocks
  2. 4. Ediacaran fossils lacked hard ________, making it hard for them to be fossilized
  3. 6. Human beings are complex cellular beings called _________.
  4. 8. Eon during the Precambrian during which organisms first appeared
  5. 9. The cycle that explains the opening and closure of ocean basins
  6. 10. One of the two requirements for “life”
  7. 13. Populations of organisms that can interbreed and reproduce
  8. 14. Type of selection that favors individuals that can best adapt to their environment
  9. 16. The first documented supercontinent
  10. 18. Type of evolution mixing newly evolved and ancestral characteristics
  11. 19. Type of evolution where unrelated organisms develop similar features
  12. 21. Largest eon of the Precambrian