Geologic Time Scale

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Across
  1. 3. A fossil that is useful for dating and correlating the strata in which it is found.
  2. 4. The amount of time it takes for half of a remaining isotope to decay to a daughter product.
  3. 6. The numeric age of a layer of rocks or fossils that can be found by using this method.
  4. 7. Any rock or fragment that’s included inside of another rock is older than the rock in which it is included.
  5. 8. A major division of geological time, subdivided into eras.
  6. 9. An expert in or student of geology.
  7. 11. In a sequence of sedimentary rock layers, the newer rock layers will be on top of the older ones.
Down
  1. 1. Any feature that cuts across a sequence of rocks, is younger than everything it cuts.
  2. 2. You may not know the exact age, but you can tell if one rock layer is older relative to another layer.
  3. 5. Recognized to represent a period of time, or on radioactive decay of specific isotopes.
  4. 10. An object at rest stays at rest as long as no force acts on it.