Geologic Time Lab - Geology 105 Lab Packet Key to Map

1
Figure 8.2
Key to Map Symbols used throughout this lab.
Geologic Time Lab - Geology 105 Lab Packet
Figure 8.15
Figure 8.14
2
Figure 8.10
Figure 8.9
3
Figure 8.16
N
Figure 8.11
4
Questions Please place your answers on the
answer sheet provided by your instructor. 4.
Analyze the fossiliferous rock in Figure 8.14.
a. Based on Figure 8.13, what is the relative
age of the rock in Figure 8.14? b. Based on
Figure 8.13, what is the absolute age of the rock
in Figure 8.14? 5. Analyze the fossiliferous
rock in Figure 8.15. a. Based on Figure 8.13,
what is the relative age of the rock in Figure
8.15? b. Based on Figure 8.13, what is the
absolute age of the rock in Figure 8.15? 6.
Examine the geologic cross section in Figure 8.2
on the basis of its fossils. a. Which of the
contacts between lettered layers is a
disconformity.? b. What geologic Periods are
missing here? c. If the present landscape in
this cross section were covered today with a
layer of sediment, then how much time would the
resulting disconformity represent. Explain your
reasoning. 8. A solidified lava flow containing
zircon mineral crystals is present in a sequence
of rock layers that are exposed in a hillside. A
mass spectrometer analysis was used to count the
atoms of Uranium 235 and Lead 207 isotopes in the
zircon samples from the lava flow. The anaylsis
revealed that 71 of the atoms were Uranium
235,and 29 of the atoms were Lead 207. a.
About how many half-lives of the Uranium 235 to
Lead 207 decay pair have elapsed in the zircon
crystals?? b. What is the absolute age of the
lava flow based on the zircon crystals? c.
What is the age of the rock layers below the lava
flow? d. What is the age of the rock layers
above the lava flow? 9. Astronomers think the
Earth if probably formed at the same time as all
the other rocky materials in our solar system,
including the oldest meteorites. The oldest
meteorites ever found on Earth contain nearly
equal amounts of both Uranium 238 and Lead 206.
Based on the charts in Figure 8.16, what is
Earths age? Explain your reasoning.
Figure 8.13