Download Chapter 16 Review Pages 566

Page 1 of 4
Chapter Review
Natural forces break rocks apart and form soil,
which supports life.
CONTENT REVIEW
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KEY CONCEPTS SUMMARY
1
Mechanical and chemical forces break down rocks.
Over time,
mechanical
weathering
breaks a
rock into
smaller
pieces.
2
Chemical
weathering
affects exposed
rock surfaces.
VOCABULARY
weathering p. 543
mechanical
weathering p. 544
exfoliation p. 544
abrasion p. 544
chemical weathering
p. 546
Weathering and organic processes form soil.
VOCABULARY
Soil has measurable properties, such as color, texture, pore space,
and chemistry.
humus p. 551
soil horizon p. 552
soil profile p. 552
Soil is a mixture
of weathered
rock, organic
matter, water,
and air.
Plants, microorganisms,
and animals affect soil
characteristics.
3
Human activities affect soil.
VOCABULARY
Soil is essential to life and takes a long time to form. It is difficult or
impossible to replace soil that has been lost.
desertification p. 561
Soil Loss
Farming, construction
and development,
and mining are three
human activities that
affect soil.
566 Unit 4: Earth’s Surface
Soil Conservation
Soil conservation
practices help keep
soil from blowing or
washing away.
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Reviewing Vocabulary
Copy the three-column chart below. Complete
the chart for each term. The first one has been
done for you.
Term
Definition
Example
EXAMPLE
the breakdown
of rocks by
chemical
reactions that
change the
rocks’ mineral
composition
Iron reacts
with air and
water to form
iron oxides or
rust.
chemical
weathering
1. mechanical
weathering
2. abrasion
3. exfoliation
4. desertification
Reviewing Key Concepts
Multiple Choice Choose the letter of the
best answer.
5. The force of expanding water in the cracks
and pores of a rock is an example of
a. chemical weathering
b. mechanical weathering
c. oxidation
d. desertification
6. The breakdown of a rock by acidic water is
an example of
a. chemical weathering
b. mechanical weathering
c. oxidation
d. desertification
7. Soil is a mixture of what four materials?
a. granite, limestone, nitrogen, and air
b. plant roots, iron oxides, water, and air
c. rock particles, plant roots, humus,
and nitrogen
d. rock particles, humus, water, and air
8. What is the main component of soil?
a. humus
c. air
b. water
d. rock particles
9. What is humus?
a. the decomposed rock particles in soil
b. the decomposed organic matter in soil
c. the material that makes up the B horizon
d. the material that makes up the C horizon
10. Three factors that affect the rate of
weathering are
a. microorganisms, plants, and animals
b. weather, landforms, and rainfall
c. surface area, rock composition, and climate
d. texture, color, and pore space
11. Microorganisms affect the quality of soil by
a. decomposing organic matter
b. creating tunnels
c. absorbing water
d. increasing mechanical weathering
12. The movement of air and water through
a soil is influenced most by the soil’s
a. color and chemistry
b. texture and pore space
c. pH and nitrogen content
d. microorganisms
13. Contour plowing, strip-cropping, and
terracing are conservation methods
designed to reduce the
a. runoff of water
b. activity of microorganisms
c. acidity of soil
d. pore space of soil
Short Answer Write a few sentences to
answer each question.
14. How do farming, construction and
development, and mining affect soil?
15. How do ice wedging, pressure release,
plant root growth, and abrasion cause
mechanical weathering?
16. How do air and water cause chemical
weathering?
Chapter 16: Weathering and Soil Formation 567
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Thinking Critically
Use the photograph to answer the next
three questions.
26. ANALYZE Copy the concept map below and fill
it in with the following terms and phrases.
acidic water
damaged statue
mechanical weathering
oxygen and water
rounded rocks
chemical weathering
exfoliation
moving water
pressure release
rust
WEATHERING
type that causes
physical changes
17. APPLY Make a sketch of the soil profile above,
labeling the A, B, and C horizons.
18. OBSERVE What does the color of the top layer
indicate about this soil?
type that causes
changes in mineral
composition
results in
results in
caused by
caused by
19. APPLY Which part of the profile is most affected
by chemical and mechanical weathering? Why?
20. APPLY Suppose that you own gently sloping
farmland. Describe the methods that you
would use to hold the soil in place and
maintain its fertility.
21. SYNTHESIZE Describe the composition, color,
texture, and amount of pore space of a soil
that would be good for growing crops.
22. COMPARE AND CONTRAST How does mechanical
weathering differ from chemical weathering?
How are the two processes similar?
23. PREDICT What effect will the continued
growth of the world’s population likely have
on soil resources?
24. ANALYZE Soil loss is a problem all over the
world. Where might lost soil end up?
25. ANALYZE Can lost soil be replaced? Explain.
568 Unit 4: Earth’s Surface
27. ANALYZE Add to the concept map to show the
three factors that affect the rate of weathering.
28. MODEL Draw a diagram that shows an example
of a natural force breaking rocks apart to form
soil that supports life.
29. SYNTHESIZE A cycle is a series of events or
actions that repeats regularly. Describe a cycle
that involves soil and living things.
If you need to create graphs or other visuals for
your project, be sure you have grid paper, poster
board, markers, or other supplies.
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For practice on your
state test, go to . . .
Standardized Test Practice
TEST PRACTICE
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Analyzing a Table
The table indicates some of the characteristics of four soil samples.
Use the table to answer the questions below.
Sample
Color
Ability to
Hold Water
1
black
average
50%
9%
2
yellowish brown
low
70%
3%
3
reddish brown
average
60%
3%
4
very red
average to low
65%
2%
1. Soils that contain a lot of sand do not hold water
very well. Which sample probably contains the
most sand?
a. 1
c. 3
b. 2
d. 4
2. Iron gives soil a reddish color. Which sample
probably contains the most iron?
a. 1
c. 3
b. 2
d. 4
3. Crops grow best in soils with about half of their
volume consisting of pore space. Which soil has an
ideal amount of pore space for growing crops?
a. 1
c. 3
b. 2
d. 4
Extended Response
Answer the two questions below in detail. Include
some of the terms shown in the word box. In your
answers, underline each term you use.
6. Jolene is comparing a rock from a riverbed and a
rock from deep underground. One is very smooth.
The other has very sharp edges. Explain which rock
was probably found in each location.
Percentage of
Pore Space
Percentage
of Humus
4. What soil color might indicate a high level of
organic matter?
a. black
c. red-brown
b. yellow
d. red
5. Imagine you have an additional soil sample. The
sample is dark brown, has an average ability to
hold water, and has 55% pore space. What
percentage of humus would this soil most likely
contain?
a. 1%
c. 3%
b. 2%
d. 8%
abrasion
chemical weathering
ice
mechanical weathering
moving water
plant roots
rusting
7. In a museum, Hank sees two iron knives that were
made in the early 1800s. One has spent 200 years
on the top of a fortress wall. The other one has
been stored in the museum for 200 years.
Why might the two knives look different?
Chapter 16: Weathering and Soil Formation 569