Question

for questions 14 to 18, read each question carefully. decide which of the choices best completes the statement or answers the question. place your answer in the blank space given. 14. the law of superposition states that a. all rocks and fossils in a given area are the same age b. for a given sequence of rock layers, any layer is younger than the one beneath it c. all rock layers consisting of the same type of rock are the same age d. a sequence of rocks is the chronological record of a given region 15. a fossil that can be used to correlate rock layers in different locations is a(an) a. historic fossil b. stratigraphic fossil c. index fossil d. relative fossil 16. the relative age of a fossil indicates a. how long the organism lived b. the exact age of the fossil c. how long ago the fossil was dug out of the ground d. how old the fossil is compared to other fossils or rock structures that are above or below the given fossil 17. the era that spans the greatest number of years in earths geological history is the a. mesozoic b. cenozoic c. precambrian d. paleozoic 18. which of the following is a characteristic of a good index fossil? a. it is easily recognizable. b. it appears only briefly in the geological record. c. it has a wide geographical distribution. d. all of the above are correct.

Explanation:

1. The law of superposition states that in an undisturbed sequence of rock layers, the younger layers are on top of the older ones.
2. Index fossils are used to correlate rock - layers in different locations due to their wide distribution and short geological range.
3. Relative age of a fossil is about its age compared to other fossils or rock structures around it, not the exact age or how long the organism lived or when it was dug out.
4. The Precambrian era spans the longest time in Earth's geological history, from the formation of the Earth to the start of the Paleozoic era.
5. A good index fossil is easily recognizable, appears briefly in the geological record (so it can be used for narrow time - correlation), and has a wide geographical distribution.

Answer:

1. B. for a given sequence of rock layers, any layer is younger than the one beneath it
2. C. index fossil
3. D. how old the fossil is compared to other fossils or rock structures that are above or below the given fossil
4. C. Precambrian
5. D. All of the above are correct.