Chp. 6 The Rock & Fossil Record Part 1 of 2

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Across
  1. 4. a process in which radioactive isotopes tend to break down into stable isotopes of other elements
  2. 5. a principle that states that the same geologic processes shaping the Earth today have been at work throughout Earth’s history
  3. 7. determining whether an event or object, such as a fossil, is older or younger than other events or objects
  4. 10. an ideal sequence of rock-layers that contains all the known fossils and rock formations on Earth arranged from oldest to youngest
  5. 11. the largest division of geologic time
  6. 12. a surface that represents a missing part of the geologic-column
Down
  1. 1. determining the absolute age of a sample based on the ratio of parent material to daughter material
  2. 2. for a particular radioactive sample, the time it takes for one-half the sample to decay
  3. 3. the fourth-largest division of geologic time
  4. 6. a fossil of an organism that lived during a relatively short, well defined time span; a fossil that is used to date the rock layers in which it is found
  5. 8. the third-largest division of geologic time
  6. 9. preserved feces, or dung, from animals