Reg Rev #12 Geologic History

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Name: _________________________

Regents Review #12: Geologic History

1. Unconformities mean ________________ happened, so a layer is ___________. 2. ____________________ can cause folding.

D B A C E

Use the above diagram to answer questions 3 - 6.

3. Which came first, intrusion A or rock layer B? Give a reason. _____________________ _______________________________________________________________________ 4. Which came first, rock unit C or the faulting? Give a reason. ______________________ _______________________________________________________________________ 5. The wavy line at D is called an ______________________. Because it is there, we know _______________________________________________ happened. 6. What happened to the rocks at letter E immediately after they were deposited? _______________________________________________________________________ 7. Where was NYS located during the Devonian period? ____________________________ 8. When did oxygen first begin to form? _________________________________________ 9. The Earth is ________________________ years old. 10. You could find fossils of Malcurites near what city? (there are 2 possible answers) _________ ______________________________________________________________________

11. If we find fossils of corals in NYS, what does this tell us? _________________________ ______________________________________________________________________ 12. Earth’s atmosphere was formed by ingassing/outgassing from Earth’s interior. 13. Good index fossils are species that existed for a long/short time and are they are found in a widespread/small area. 14. What else can also be a good time marker? ____________________________________ 15. Define half life: __________________________________________________________ 16. Radioactive decay is/is not affected by the mass of the sample, temperature, or pressure. 17. Carbon-14 can be used to date any remain that is a. _________________________________________________________________ b. _________________________________________________________________

The above graph shows the decay of a radioactive isotope. Use it to answer 18 – 21.

18. Which line represents the radioactive isotope? _________________________________ 19. IF this graph was representing C 14 ( which it isn’t!

) the other line would represent _________ 20. Approximately how long is the half-life for this substance? ________________________ 21. After how many days would 25% of the isotope be left? __________________________ 22. How do we know that this is NOT C 14 ? _______________________________________ 23. About how long does it take for 75% of all the C 14 in a sample to become N 14 ? ________

Regents Review #12: Geologic History KEY

1. weathering and erosion, missing 2. Earthquakes 3. B because it is affected by contact metamorphism. 4. C because is affected by the faulting. 5. Unconformity, weathering and erosion 6. Tilting or folding. 7. Near the equator 8. During the Middle Archean Eon 9. 4.6 billion 10. Watertown or Oswego 11. NYS was once covered by a warm shallow sea OR NYS was not always located at 40  N OR it must have been closer to the equator OR supports the theory of continental drift 12. outgassing 13. short, widespread 14. Volcanic ash/meteorite deposits 15. time it takes for HALF of the material to break down 16. is not 17. 19. N 14 a. Organic b. Less than 70,000 years old 18. The one that is going down. 20. 5 days 21. 10 days 22. The half life is only 5 days 23. 11,400 years.

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