Vocab tic-tac-toe

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Across
  1. 2. The time it takes for a radioactive substance to decay to half of its original amount.
  2. 3. A scientific method used to determine the age of an object containing organic material by analyzing the properties of radiocarbon, a radioactive isotope of carbon.
  3. 4. States that within a sequence of layers of sedimentary rock, the oldest layer is at the base and that the layers are progressively younger with ascending order in the sequence.
  4. 7. Method used to determine the age of rocks, fossils, and other geological features by comparing them to one another.
  5. 9. The age of a geologic phenomenon measured in present Earth years, rather than its age relative to other geologic phenomena.
Down
  1. 1. A radiometric dating technique that compares two isotopes of uranium in a sample.
  2. 5. The remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.
  3. 6. The process by which an unstable atomic nucleus loses energy by radiation.
  4. 8. Refers to the representation of time based on the rock record of Earth.