Skip to main content
Geosciences LibreTexts

1.10: Student Responses

  • Page ID
    5448
  • The following is a summary of the questions in this lab for ease in submitting answers online.

    1. In Figure 1.8, which of the following rock layers is the oldest?

    a. A                         b. B                         c. C

     

    2. Which Geologic Law did you use to come to the conclusion you made in the previous question?

    a. The Law of Superposition                         b. The Law of Cross-Cutting                         c. The Law of Original Horizontality                         d. Unconformities

     

    3. In Figure 1.9, which of the following geologic structures is the youngest?

    a. A                         b. B                         c. C

     

    4. Which Geologic Law did you use to come to the conclusion you made in the previous question?

    a. The Law of Superposition                         b. The Law of Cross-Cutting                         c. The Law of Original Horizontality                         d. Unconformities

     

    5. Examine unconformities 1 and 2 indicated in Figure 1.9. Which of the following statements about them is true?

    a. The older unconformity is a Nonconformity, while the younger is an Angular Unconformity.

    b. The older unconformity is a Disconformity, while the younger is a Nonconformity.

    c. The older unconformity is a Nonconformity, while the younger is a Disconformity.

    d. The older unconformity is an Angular Unconformity, while the younger is a Disconformity.

     

    6. Examine the Unconformity shown in Figure 1.10. What type of unconformity is this?

    a. Angular Unconformity                         b. Nonconformity                         c. Disconformity

     

    7. Which of the above geologic events is the second in the sequence?

    a. A                         b. B                         c. C                         d. D                         e. E                         f. F                         g. G                         h. H

     

    8. Which of the above geologic events is the fifth in the sequence?

    a. A                         b. B                         c. C                         d. D                         e. E                         f. F                         g. G                         h. H

     

    9. Which of the above geologic events is the seventh in the sequence?

    a. A                         b. B                         c. C                         d. D                         e. E                         f. F                         g. G                         h. H

     

    10. Based on the assemblage of organisms (A-I) in this sample, what is the age of this rock?

    a. Economy                                             b. Southgate                                             c. McMicken                                             d. Mt. Hope

    e. Fairmount                                            f. Bellevue                                                g. Corryville                                             h. Mt. Auburn

     

    11. Which organism was the most useful in coming to this conclusion (which is the best index fossil)?

    a. Isotelus                                             b. Zygospira                                               c. Cyclonema                                           d. Vinlandostrophia

    e. Parvohallopora                                   f. Cincinnetina                                            g. Streptaster                                           h. Ambonychia

     

    12. Which organism was the least useful in coming to this conclusion (which is the worst index fossil)?

    a. Isotelus                                             b. Zygospira                                               c. Cyclonema                                           d. Vinlandostrophia

    e. Parvohallopora                                   f. Cincinnetina                                            g. Streptaster                                           h. Ambonychia

     

    13. How much of the parent isotope would be remaining after 7 half-lives have passed?

    a. 6.25%                         b. 1.56%                         c. 0.78%                         d. 0.39%

     

    14. If a radiometric element has a half-life of 425 years, how old would a rock be that only had 3.125% of the parent isotope remaining?

    a. 2125 years                         b. 1700 years                         c. 2550 years                         d. 3400 years

     

    15. Based on your graph above, approximately how much of the parent isotope would be remaining after 3.5 half-lives?

    a. 16%                         b. 12%                         c. 4%                         d. 8%

     

    16. Based on your graph above, approximately how many half-lives have passed when only 35% of the parent isotope is remaining?

    a. 0.75                         b. 1.5                         c. 2.1                         d. 2.5

     

    17. An Archeologist finds some cotton cloth at a burial site and wants to determine the age of the remains. Which isotopic system should they use?

    a. Carbon-14                         b. Uranium                         c. Potassium-Argon

     

    18. The Archeologist determines that there is 16.7% of the parent isotope remaining in the cloth sample. How old is the burial site? Hint: you can find the length of the half-life in the reading above.

    a. 13,559 years                     b. 14,798 years                     c. 16,743 years                     d. 1.66 billion years                     e. 1.81 billion years                     f. 2.05 billion

     

    19. A geologist is trying to date a sequence of sedimentary rocks with abundant fossils and sandstones. Within the sequence is a distinctive clay layer that under closer inspection is fine-grained volcanic ash. Which of the following is the best way to obtain an absolute date for the sequence of rocks?

    a. Carbon date the fossils                     b. Potassium-Argon date the sands                     c. Uranium date the Zircons in the ash                     d. Identify the index fossils

     

    20. The geologist determines there is 78.3% of the parent remaining in the sample that they examine. How old is the sequence of rocks? Hint: you can find the length of the half-life in the reading above.

    a. 187.5 million years                                                     b. 247.8 million years                                                         c. 390.7 million years

    d. 2.504 billion years                                                      e. 1.588 billion years                                                          f. 1.202 billion years