Geological time scale

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Across
  1. 4. when layers of rock is older than another layer
  2. 5. first known glaciations occurred
  3. 9. exact age of someone
  4. 10. The time era ends when a ___ happens
Down
  1. 1. is the youngest layer/newest
  2. 2. the remains or impression of a prehistoric organism
  3. 3. is the oldest layer
  4. 6. not an exact number or age
  5. 7. modern bases of life was in place
  6. 8. earth's crust cooled during this time