Geologic Time Scale

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Across
  1. 2. Lasted from 1000 to 850 million years ago
  2. 4. No longer in existence
  3. 5. Lasted from 2300 to 2050 million years ago; global glaciation began
  4. 7. From 280 million to 230 million years ago
  5. 10. From 63 million to 58 million years ago; appearance of birds and earliest mammals
  6. 12. Approximately the last 63 million years
  7. 15. From about 501 to 488 million years ago; marked by an "explosion" of life
  8. 16. From 230 million to 190 million years ago
  9. 18. lasted from 1800 to 1600 million years ago; supercontinent Columbia formed
  10. 21. Lasted from 2050 to 1800 million years ago; large asteroid collision created the Vredefort impact structure
  11. 22. starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago
  12. 23. A process of fossilization by gradual substitution of mineral matter for the original organic matter Also called petrification
  13. 27. From 58 million to 40 million years ago; presence of modern mammals
  14. 28. Lasted from 2 million to 11000 years ago; the time of human evolution
  15. 32. A fossil formed when an animal, plant, or other organism dies and is covered by sediment
  16. 34. From 40 million to 25 million years ago; appearance of sabertoothed cat
  17. 35. A fossil formed when an animal, plant, or other organism dies, its flesh decays and bones deteriorate due to chemical reactions; minerals gradually enter into the cavity
  18. 36. From 310 million to 280 million years ago
  19. 40. From 135 million to 63 million years ago
  20. 41. Lasted from 2500 to 2300 million years ago; the oxygen catastrophe
  21. 42. Lasted from 850 to 635 million years ago
  22. 43. The last 10000 years
  23. 44. From 25 million to 13 million years ago; appearance of grazing mammals
  24. 45. From 13 million to 2 million years ago; growth of mountains; cooling of climate; more and larger mammals
  25. 47. From 230 million to 63 million years ago
  26. 48. From 544 million to about 500 million years ago; marine invertebrates
Down
  1. 1. Lasted from 1200 to 1000 million years ago
  2. 3. The process by which organic material is converted into stone through the replacement of the original material and the filling of the original pore spaces with minerals
  3. 6. From 433.4 ± 1.5 to 427.4 ± 2.8 mya, is subdivided into the Sheinwoodian (to 430.5 million years ago) and Homerian ages
  4. 8. began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago
  5. 9. From 423 ± 1.5 to 419.2 ± 2.8 mya, is the final and shortest epoch of the Silurian
  6. 11. The remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock
  7. 12. From about 299 to 270 million years ago; marked by the appearance of beetles and flies
  8. 13. Lasted from 1400 to 1200 million years ago
  9. 14. Lasting from roughly 358.9 ± 0.4 to 323.2 ± 0.4 million years ago
  10. 17. Last 2 million years
  11. 19. Hard translucent fossilized resin
  12. 20. From 544 million to about 230 million years ago
  13. 24. The process by which different kinds of living organisms are thought to have developed and diversified from earlier forms
  14. 25. From about 260 to 251 million years ago; marked by the formation of the Pangea supercontinent
  15. 26. From 542 to ~510 million years ago; first appearance of trilobites
  16. 29. From 560 and 545 million years ago
  17. 30. From 425 million to 405 million years ago
  18. 31. From 500 million to 425 million years ago; conodonts and ostracods and algae and seaweeds
  19. 33. From 271 to 260 million years ago; rock strata and fossils were formed
  20. 37. From 443.4 ± 1.5 to 433.4 ± 2.8 mya, and is subdivided into three stages: the Rhuddanian,[8] lasting until 440.8 million years ago, the Aeronian, lasting to 438.5 million years ago, and the Telychian
  21. 38. From 405 million to 345 million years ago
  22. 39. From 190 million to 135 million years ago
  23. 42. Lasted from 1600 to 1400 million years ago
  24. 46. Lasting from 427.4 ± 1.5 to 423 ± 2.8 mya, comprises the Gorstian stage, lasting until 425.6 million years ago