numeric and relative dating

1. Distinguish between numeric and relative dating. 5

2. If sedimentary layers (beds) are steeply inclined in an exposure (outcrop) of rock, what principle allows you to assume that the beds were tilted after they were deposited? 5

3. How do index fossils allow us to determine the relative ages of rock strata? 10
4. Is there one place on Earth where we can see the complete geologic column?
10

5. What is meant by the term correlation, and why are fossils such powerful tools in correlating strata over great distances? 10

6. What kinds of rocks€”igneous, sedimentary, or metamorphic€”are best for radiometric dating? Why? 10

7. During the process of radioactive decay, a hypothetical atom lost two protons and two neutrons from its nucleus. The original atom had an atomic number of 10 and atomic mass of 28. Do the following:
a. What is the new atomic number of the atom (after that loss)? 5
b. What is the new atomic mass number of the atom (after that loss)? 5

8. If radioactive decay began with 400,000 parent isotopes, how many would be left after three half-lives? 5
a. 200,000 b. 50,000 c. 100,000 d. 25,000

9. The half-life of a radioactive isotope is 500 million years. Scientists testing a rock sample discover that the sample contains three times as many daughter atoms as parent isotopes. What is the age of the rock? 5
a. 500 million b. 1,000 million years
c. 1,500 million years d. 2,500 million years

10. If a radioactive element has half-life of 16 million years, what fraction of the original amount of parent material will remain after 96 million years? What percen
tage will that be?