Geologic Time Scale

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