Geologic Time Vocab

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Across
  1. 1. geologic time unit divided into periods
  2. 7. geologic time unit that is divided into epochs
  3. 8. geologic time unit that is divided into ages
  4. 10. sudden catastrophic event when a significant percentage of all life forms become extinct
  5. 12. most recent 541 million yrs of geological time, including the present, represented by rocks that contain evident, abundant fossils
Down
  1. 2. age of a geologic event based on the absolute number of years ago it occurred
  2. 3. chronological arrangement of geologic time subdivided into eons, eras, periods, epochs, and ages
  3. 4. shortest unit of geologic time
  4. 5. an approach to determining the timing of geologic events based on the order in which they occurred
  5. 6. all of geologic time before the Paleozoic Era, encompassing approx the first 4 billion years, or 90% of Earth's history; all rocks formed during that time
  6. 9. longest unit of geological time, divided into eras
  7. 11. absence of oxygen