Geologic Dating Methods

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Across
  1. 5. After three half lives, you expect this percent of a radioactive substance to remain.
  2. 6. The process in which an element releases radiation to become stable.
  3. 10. The Earth is approximately __ years old.
  4. 12. The half live of C-14 in years.
  5. 13. After one half of a half life, you expect this percent of a radioactive substance to remain.
  6. 14. Radiation that releases helium atoms.
  7. 17. The guy who was the first to determine the age of the Earth.
  8. 19. The idea that a process you can observe likely happens elsewhere in the same way.
  9. 22. The naturally preserved remains of living organisms.
  10. 23. Radiation that causes a radioactive element to lose 4 amu.
  11. 24. Radiation that releases electrons.
  12. 25. After one half life, you expect this percent of a radioactive substance to remain.
  13. 26. The time it takes 50% of a material to decay.
  14. 27. The most dangerous type of radiation.
  15. 28. The idea that sediments are originally formed in flat layers.
Down
  1. 1. After five half lives, you expect this percent of a radioactive substance to remain.
  2. 2. The half life of U-238 in years.
  3. 3. Any time the rock layers are messed up from the rock cycle, erosion, etc.
  4. 4. __ __ is used to determine the age of many animal remains.
  5. 7. Different versions of the same element are called __.
  6. 8. After four half lives, you expect this percent of a radioactive substance to remain.
  7. 9. After two half lives, you expect this percent of a radioactive substance to remain.
  8. 11. Patterson used the decay rate of __ to determine the age of the Earth.
  9. 15. Patterns of rock formed by intrusions.
  10. 16. Radiation that releases light.
  11. 18. The decimal on the atomic mass of most elements comes from the __ of all known isotopes.
  12. 20. Determining the age of something by comparing it to its surroundings.
  13. 21. Chunks of older rock broken off in younger rock.