Name: ________________________________________________________________________ Date: _________ Hour :_____
Fossils & Geologic Time
Study Guide
Directions: Answer the following questions in complete sentences. YOU MUST RE-WRITE THE SENTENCE STEM FOR FULL
CREDIT!
1. Define the following terms in your own words (complete on a separate paper and attach):
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fossil
rock
geological history
timeline
relative dating
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rock layers
earth processes
erosion
glacier movement
environmental conditions
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weathering
wind
water movement
2. In what type of rock are fossils found?
3. How do we use rock layers to determine geological history?
Fossils are found in sedimentary rock.
Rock layers are used to determine geological history by seeing what order the rock
layers formed in. We know that the oldest rock layers are found on the bottom and the
youngest rock layers are found on the top.
4. Describe how the principle of superposition is used in
relative dating of rocks.
5. If a fossil is found in a rock layer, what do we know about
the relative age of the fossil?
The principle of superposition is used in relative dating of rocks because
the oldest rock layers are on the bottom and each layer going up is younger.
If a fossil is found in a rock layer, we know that the relative age of the fossil
is the same as the relative age of the rock layer. The fossil must have lived
and died in the same time period that the rock layer formed.
Use the diagram to the right to answer the following questions:
6. Which rock layer is oldest? How do you know?
The oldest rock layer is D.
I know this because it is on the bottom.
7. Which rock layer is youngest? How do you know?
The youngest rock layer is A.
I know this because it is on the top.
8. Which fossil is older: the one in rock layer C or rock layer B? Why?
The older fossil is found in rock layer C.
This is true because rock layer C is below rock layer B, making the rock layer older. The rock layer that is older contains the fossil that is older, because the
fossil must have lived at the same time that the rock layer was forming.
Use the diagram to the right to answer the following questions. You do not need to write in complete sentences for this part.
Instead, write the letter of the correct answer.
9.
a) Which rock layer is older: D or
B?
b) Which rock layer is older: B or E?
c) Which rock layer is younger: D
or F?
d) Which rock layer is younger: D or
C?
Use the timeline below to answer the following questions.
BYA
10. How many billions of years ago did Earth form?
11. What happened approximately 2.6 bya?
Earth formed 4.56 bya.
Approximately 2.6 bya cells with nucleuses appeared.
12. Which occurred first: the rise in atmospheric
oxygen or the moon formation?
13. Approximately how long ago did hard-shelled animals
appear?
The event that occurred first is the moon formation.
Hard-shelled animals appeared approximately 0.6 bya.
14. Which occurred first: the core formation or
Jack Hills Zircon?
15. What event on the timeline occurred most recently?
The event that occurred first is the core formation.
of humans.
The event on the timeline that occurred most recently is the appearance
16. What 3 things do fossils provide ? (Hint: see your notes)
Fossils provide a historical perspective on change on Earth, a biological
record of life on Earth, and a record of how organisms have changed
over time.
17. What is the fossil record?
The fossil record is a record of fossils found and when they lived.
18. How do geologists use the fossil record to determine
geological history?
Geologists use the fossil record to determine geological history by
looking at when fossils lived and seeing how life on Earth has evolved
over time.
Use the fossil record to the right to answer the following
questions:
19. During what period did reptile diversity occur?
Reptile diversity occurred during the Permian period.
20. What occurred during the Silurian period?
During the Silurian period, the first vascular land plants appeared.
21. During what period did the first amphibians appear?
22. What occurred during the Jurassic period?
The first amphibians appeared during the Devonian period.
During the Jurassic period, the first birds appeared and dinosaurs diversified.
23. Give an example of erosion.
24. How can erosion expose rock layers?
An example of erosion is water breaking down a rock at the beach.
Erosion can expose rock layers by removing the layer on top, thus exposing
the layer below.
25. Describe the process of mountain building.
26. Can mountain building change the shape of Earth’s surface?
The process of mountain building occurs when two tectonic
plates of equal densities collide and fold up.
Mountain building can change the shape of Earth’s surface.
27. Explain what happens to mountains when they go through erosion.
When mountains go through erosion the peaks become rounded hills.
28. How are rocks used to measure geologic time?
Rocks are used to measure geologic time by looking at the layers and the fossils inside of them. Geologists observe and study the details of the rocks.
29. What is a glacier?
A glacier is a slow moving mass of ice created when
snow is compacted together.
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30. How can glacier movement change the surface of Earth?
Glacier movement changes the surface of Earth by carving out mountains and
moving rocks out of mountains.
CONSTRUCTED RESPONSE:
Why do geologists need to understand the processes of erosion, mountain building, and glacier movement in order to properly
use rocks to determine geological history?
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Explain how geologists use rocks to determine geological history (1 point)
o Sentence stem: Geologists use rocks to determine geological history by…
Describe erosion OR mountain building OR glacier movement (1 point)
o Sentence stem: Erosion/mountain building/glacier movement is…
Explain why a knowledge of the process you chose (erosion, mountain building, or glacier movement) is needed to use
rocks to determine geological history (1 point)
o Sentence stem: A knowledge of the process of _____________ is needed to use rocks to determine geological history
because…
Fossils & Geologic Time
Vocabulary Definitions
fossil: the preserved remains of a once-living organism
rock: a naturally occurring solid mixture of minerals or organic matter
geological history: the history of Earth based on a geologic time scale
timeline: a way of displaying events in order based on when they occurred
relative dating: any method of determining whether an object or event is older or younger than another
rock layers: layers of rock which are used to determine relative age
earth processes: processes that shape Earth’s surface
erosion: the process by which wind, water, ice, or gravity transports soil and sediment from one location to
another
glacier movement: the movement of a large mass of ice called a glacier
environmental conditions: the state of the environment at a given time
weathering: the breaking down of rocks
wind: a natural movement of air
water movement: the movement of water