Chp. 6 The Rock & Fossil Record part 2 of 2

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Across
  1. 4. a surface that represents a missing part of the geologic-column
  2. 6. a principle that states that all geologic change occurs suddenly
  3. 7. for a particular radioactive sample, the time it takes for one-half the sample to decay
  4. 8. determining the absolute age of a sample based on the ratio of parent material to daughter material
  5. 10. a principle that states that younger rocks lie above older rocks in undisturbed sequences
  6. 11. a process in which radioactive isotopes tend to break down into stable isotopes of other elements
  7. 12. process of establishing the age of an object, such as a fossil or rock layer, by determining the number of years it has existed
Down
  1. 1. a principle that states that the same geologic processes shaping the Earth today have been at work throughout Earth’s history
  2. 2. any naturally preserved evidence of life
  3. 3. determining whether an event or object, such as a fossil, is older or younger than other events or objects
  4. 5. an ideal sequence of rock-layers that contains all the known fossils and rock formations on Earth arranged from oldest to youngest
  5. 9. atoms that have the same number of protons but different numbers of neutrons