Geologic Time Scale Crossword

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Across
  1. 3. Fossil where empty pore spaces are filled in by minerals such as in petrified wood
  2. 5. Preserved evidence of an organism
  3. 6. Event in which all of a species disappears suddenly, usually through natural disaster
  4. 10. Period that included the Oligocene and Eocene
  5. 11. Epoch 56 to 34 million years ago
  6. 12. Period 630 million to 542 million years ago
  7. 14. Number of eras in the Phanerozoic eon
  8. 18. Cause of the mass extinction of the dinosaurs after the Cretaceous period, 65 million years ago
  9. 19. Groups of organisms rapidly diversified in the _______ explosion in the ________ period
  10. 20. Birds evolved from ________, who lived in the Mesozoic era
  11. 21. The modern humans appear and the ice ages occur in this epoch that is before the Holocene
  12. 22. Period in which dinosaurs appeared and gymnosperms become dominant
  13. 24. Fossil that is similar to mold in which the mold in filled with sediment
  14. 25. Epoch in which humans began to form civilizations
  15. 26. Extensive glaciation occurred” before the______
  16. 27. Period from 359.2-299 million years ago
  17. 29. Period from 201.3 to 145 million years ago
  18. 30. Period in which the reptiles scattered
  19. 31. Occurred 485.4 to 443.4 million years ago, in the Paleozoic period
  20. 35. A type of fossil in which preserved tree sap traps an entire organism
  21. 37. By the end of the Carboniferous period, the first ____ began to roam the forests
  22. 39. When land plants and insects appear and coral and invertebrates are dominant
  23. 41. Movement of plate ________ that make up the surface of Earth
  24. 42. The oldest fossils of prokaryotes were from this period
  25. 43. Fossil in which an impression of the organism is preserved
Down
  1. 1. Epoch 34 million to 23 million years
  2. 2. The model that expresses the major geological and biological events in Earth's history is known as the ________ time scale
  3. 4. Epoch 5.332 million to 2.588 million years
  4. 7. Largest division divides the scale into ______ parts
  5. 8. The land mass that existed on Earth 225 million years ago
  6. 9. Era that means "recent life"
  7. 10. Era in which the Cambrian and Silurian periods occurred
  8. 13. Period in which invertebrates and algae diversify
  9. 15. Epoch in which the mammals, birds, and insects scatter
  10. 16. 90 percent of all history; from formation of Earth to 542 million years ago
  11. 17. The oldest era in which multicellular organisms appear
  12. 19. Period from 145 to million years ago that ended with a mass extinction
  13. 23. Epoch in the Neogene, 23.03 to 5.332 million years ago
  14. 28. Type of fossil in which the original material is replaced with mineral crystals
  15. 32. Period in which mass extinction occurs and sharks and bony fish appear
  16. 33. The meteorite that struck Earth in the Paleogene period caused a change in global _______
  17. 34. Period in which the apes appear and humans form civilizations
  18. 36. Earth's _________ was 4.6 billion years ago
  19. 38. Era that included the Jurassic and Triassic
  20. 40. Element found in the K-T boundary that is not prevalent on Earth