Assignments for Geological Time Scale
1. Geological Travel Brochure (see instructions) (40 points)
http://www.paleoportal.org/index.php?globalnav=time_space
http://paleobiology.si.edu/geotime/main/
2. Relative Dating Worksheets (10 points)
3. Absolute Dating Activity and worksheet. (10 points)
4. Paleoclimate activity (5 points)
5. http://www.paleoportal.org/index.php?globalnav=time_space Follow geological time scale in the state of your
choice. What periods have records? Note any interesting formations and interesting fossils. (5 points)
6. Watch video at http://www.pbs.org/wgbh/nova/sciencenow/3318/01.html What extinction theories do they
discuss? Are these theories subject to change? Which theory do you like best, and why? (5 points)
Below is a list of events for the volcano extinction theory from the video. Put them in chronological order.
_____ a. Anaerobic bacteria thrive in the oceans and produce hydrogen sulfide as a waste product
_____ b. Atmospheric carbon dioxide levels increase
_____ c. Atmosphere warms
_____ d. Dissolved oxygen levels in the oceans drop
_____ e. Hydrogen sulfide accumulates in the oceans and atmosphere
_____ f. Most aquatic life that depends on oxygen dies
_____ g. 95 percent of Earth's life is killed by hydrogen sulfide
_____ h. Oceans warm
_____ i. Volcanoes erupt
7. Watch “The Day the Mesozoic Died.” http://www.hhmi.org/biointeractive/day-mesozoic-died
Complete worksheet. (5 points)
8. Enigma Jigsaw activity. (5 points)
9. Read Working Together. Write a summary paragraph.
10. Map Skills (6 points)
See below
11. Nebraska Geology (5 points)
12. Answer each of the following. (10 points)
a. Draw an example of each: intrusion, extrusion, fault, and unconformity. Write a sentence about how each is
used for relative dating.
b. Explain dating of sedimentary rock using radioactive dating of extrusion and intrusion.
c. What is an index fossil and how is it used for relative dating?
d. What is evolution?
e. Write a paragraph about how scientists think the moon formed.
f. What can fossils tell us about the changes in the earth’s surface?
g. Hypothesize how the formation of Pangaea affected evolution.
h. Hypothesize how mass extinctions affected evolution.
i. Define the Principles of Superposition, Original Horizontality, Lateral Continuity, and, Uniformitarianism.
11. Horses and Saber-toothed Tigers
For six years, a team of paleontologists searched for horse fossils. Based on their fossil finds, the
scientists concluded that as the environment changed, the physical appearance of ancient horses
changed. The paleontologists also unearthed the fossils of two prominent type of saber-toothed
tigers, designated Tigers A and Tigers B, that shared the environment with, and were predators of
the horse. Tiger A had a bulky body, was built more for strength than for speed, and probably
preferred ambush to chasing prey. Tiger B was smaller and faster than Tiger A.
The scientists measured the lengths in centimeters (cm) of fossil horse skulls, assuming that as the
horse's average skull size increased or decreased, the average length of a horse’s body generally
increased or decreased in the same proportion. The following table summarizes the results of the
scientists' measurements. Each X on the chart represents a horse fossil find. Each A or B represents
the finding of, respectively, a Type A or B saber-toothed tiger fossil.
Age of
fossils
(millions of
yrs)
Number of horse fossils found with a skull length (cm) of:
12
16
20
24
28
13
32
36
40
44
X
XXXX
XX
X
XX
X
X
x
X
Saber-toothed
tiger fossils
found
BBB
15
17
19
X
21
XX
X
XXX
X
XX
X
X
BB
AB
AA
23
X
XXX
X
AAA
25
X
XXXX
X
AAAA
27
X
XXX
XX
AAAA
29
X
XXXX
X
AAA
31
X
XXXX
X
AAA
i. What can you hypothesize about the kinds of tigers and horses that were found in the same layers?
j. Drawing from your own knowledge as well as information contained in the table, explain why the
paleontologist team found no horse or cat fossils in the strata (rock layers) that were deposited 15 million years
ago.
Map Skills
Name ________________________
Use the Geologic Map of Nebraska below to answer the following questions.
Along the eastern edge of Nebraska, defined by the Missouri River, is ancient sedimentary rock of
Pennsylvanian (gray) and Permian (blue) age. Cretaceous rocks (green) occur mainly in the east, but also
are exposed in the valleys of the Missouri and Niobrara rivers in the north, the White River in the extreme
northwest and the Republican River in the south. Almost all of these are marine rocks, laid down in
shallow seas.
The majority of the state is of Tertiary (Cenozoic) age. A few slivers of Oligocene rocks crop out in the
west, as do larger areas of Miocene (pale tan), but most is of Pliocene age (yellow). The Oligocene and
Miocene rocks are freshwater lake beds ranging from limestone to sandstone, the sediment derived from
the rising Rockies to the west. They include large volcanic ash beds from eruptions in present-day Nevada
and Idaho. The Pliocene rocks are sandy and limy deposits; the Sand Hills in the west-central part of the
state derive from these.
a. What geologic periods are represented in the bedrock in Nebraska?
b. Where is the youngest bedrock in Nebraska? Where is the oldest bedrock in Nebraska?
c. If you traveled from east to west across Nebraska, how would the ages of the rock beneath you change?
d. There is a fault in southeastern Nebraska. Based on this map, what effect does it have on which rocks
are exposed?
e. Why do you think the river valleys have different bedrocks exposed than the land farther from the
rivers?
f. The first reptiles appeared in the fossil record during the Pennsylvanian period. If you wanted to look
for fossils of these reptiles in Nebraska, in what part of the state would you look? Explain your answer.
Half-life Practice Problems
1. Given: The half-life of Carbon14 is 5730 years.
a. How many half-lives will it take for 75% of the atoms to decay?
b. How many years?
c. If the ratio of parent-daughter isotopes in a sample is 20:80, how many half-lives have passed?
d. How much time has passed?
2. Iodine-131 is sometimes used to diagnose diseases. Its half-life is 60.0 days. If 2.00 g iodine-131 is
injected today, how much would be left after 1 year? Show work or explain reasoning.
3. The half-life of cesiulm-137 is 30.2 years. If after 151 years, there is 0.20 kg remaining, how much
cesium-137 was in the original sample? Show math work or explain your reasoning.
4. Given that the half-life of the radioisotope carbon-14 is 5730 years, consider a sample of fossilized
wood that, when alive, would have contained 24 g of carbon-14. It now contains 1.5 g of carbon-14.
How old is the sample? Show math work or explain your reasoning.