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11/20/2016
Chapter 7 Homework
Chapter 7 Homework
Due: 11:59pm on Sunday, September 25, 2016
To understand how points are awarded, read the Grading Policy for this assignment.
Question 1
Part A
Listed below are geographic features of the terrestrial worlds. In each case, identify the geological process: impact cratering, volcanism, erosion, or
tectonics (where tectonics is any large­scale processes affecting the structure of the planetary crust), most responsible for the feature described.
Match the geographic feature to the appropriate geologic process.
Hint 1. Are tall volcanoes required for volcanism?
ANSWER:
only the building of tall volcanoes.
Volcanism refers to the building of tall volcanoes and any subsequent lava flows that come from them.
any flow of molten lava across a surface.
Hint 2. How can you distinguish impact craters from volcanic craters?
Which of the following would tell you that craters you are observing were formed by impacts rather than volcanism?
ANSWER:
The craters are circular.
The craters have smooth bottoms indicating that lava flowed in them.
The craters are not associated with any mountains or lava flows.
Hint 3. What is tectonics?
The geological process that we call tectonics refers to __________.
ANSWER:
any surface disruption, such as stretching or crumpling, caused by stresses within the interior of the world
only surface changes, such as the movement of continents, caused by the motion of plates around the world’s surface
the surface features that we see when a world has been heavily bombarded by impacts
Hint 4. What is required for erosion?
Which of the following is necessary for erosion to occur on a planet or moon?
ANSWER:
liquid water
an atmosphere
lava flows
both liquid water and an atmosphere
both liquid water and lava flows
Hint 5. What is Valles Marineris?
ANSWER:
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Valles Marineris is a giant mountain on Mars.
a system of dried­up rivers on Mars.
a long system of canyons stretching nearly a fifth of the way around Mars, looking much like a set of giant cracks in the surface.
Hint 6. What is Olympus Mons?
ANSWER:
Olympus Mons is a giant mountain on Mars, with a crater at its top.
a huge impact crater on Mars.
a long system of canyons stretching nearly a fifth of the way around Mars, looking much like a set of giant cracks in the surface.
Hint 7. How did Mercury’s cliffs form?
ANSWER:
Mercury was bombarded by impacts.
Mercury’s long, tall cliffs are thought to have formed when the entire planet shrank, causing the surface to crumple.
water gushed through canyons and left great walls exposed as cliffs.
Hint 8. What surface features do we see in the lunar highlands?
ANSWER:
giant volcanoes.
The major surface features of the lunar highlands are craters.
smooth plateaus that must once have been flooded by lava.
ANSWER:
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Correct
Remember that the four processes are interrelated, so although one may be most important to a particular feature, others often also play a role.
For example, some erosion has occurred on the volcanic island of Hawaii, there are impact craters on the slopes of Olympus Mons, and
volcanism and tectonics almost always go hand­in­hand.
Question 2
Choose the best answer.
Part A
Which heat source continues to contribute to Earth’s internal heat?
ANSWER:
accretion
radioactive decay
sunlight
Correct
Question 3
Choose the best answer.
Part A
Which of a planet's fundamental properties has the greatest effect on its level of volcanic and tectonic activity?
ANSWER:
size
distance from the Sun
rotation rate
Correct
Question 4
Choose the best answer.
Part A
What do we conclude if a planet has few impact craters of any size?
ANSWER:
The planet was never bombarded by asteroids or comets.
Its atmosphere stopped impactors of all sizes.
Other geological processes have wiped out craters.
Correct
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Question 5
Part A
The processes responsible for virtually all surface geology are _________.
ANSWER:
impact cratering, volcanisms, tectonics, and erosion
accretion, differentiation, and radioactive decay
convection, conduction, and radiation
eruptions, lava flows, and outgassing
Correct
Question 6
Part A
Which of the following is the most basic definition of a greenhouse gas?
ANSWER:
a gas that reflects a lot of sunlight
a gas that makes a planet much hotter than it would be otherwise, even in small amounts
a gas that absorbs infrared light
a gas that keeps warms air from rising, and therefore warms the surface
Correct
Question 7
Part A
What observational evidence supports the idea that Mercury once shrank by some 20 kilometers in radius?
ANSWER:
Mercury's unusually high density
the presence of many long, tall cliffs
the presence of many impact craters
the characteristics of the Caloris Basin
Correct
Question 8
First, launch the animation below. Explore the interactive photo before beginning to answer the questions. Be sure you have clicked the “Show labels”
button.
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Part A
Assuming that features you see on Mars are similar to features found on Earth, what would a casual inspection of the interactive photo of Mars lead
you to suspect about water on Mars?
Hint 1. How many rivers, lakes, and seas are visible in the photo of Mars?
True or False? Many examples of present­day rivers, lakes, and seas are plainly visible in the photo of Mars.
ANSWER:
True
False
Hint 2. What features are visible at Mars’s north and south poles?
True or False? Polar caps are plainly visible at Mars’s poles, suggesting the presence of frozen water there.
ANSWER:
True
False
ANSWER:
Abundant surface water is found in large, brownish pools inside craters.
There are numerous small streams flowing with water.
Surface water only exists as frozen ice.
No surface water currently exists in any form.
Correct
There is nothing on the brownish surface to suggest liquid water, and close­up photos confirm that there is no liquid water on Mars today.
However, the prominent polar caps look much like Earth’s polar caps, and would therefore make you suspect that they are made of water ice. In
fact, they contain both frozen carbon dioxide and frozen water.
Part B
Which of the following Mars surface features provides dramatic evidence that volcanism has played a role in shaping the surface of Mars?
Hint 1. What surface features are signs of past volcanic activity on terrestrial planets?
True or False? The presence of either volcanoes or large lava plains indicates past volcanic activity on a terrestrial planet.
ANSWER:
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True
False
Hint 2. Do craters always indicate past volcanic activity?
True or False? The presence of craters is always a sign of past volcanic activity.
ANSWER:
True
False
ANSWER:
the polar caps
the southern highlands
Valles Marineris
Olympus Mons
Correct
Olympus Mons is a very large shield volcano. You can also see numerous other volcanoes on Mars, including three large ones on the Tharsis
bulge.
Part C
When you zoom in on the section labeled “Southern Highlands,” which geologic processes are most clearly evident?
Hint 1. What surface features are prominent in the southern highlands?
True or False? A great many craters are present in the southern highlands.
ANSWER:
True
False
Hint 2. Are all of the surface features in the southern highlands equally distinct?
True or False? Of the craters seen in the southern highlands, some have features that are more crisp and distinct than others.
ANSWER:
True
False
ANSWER:
volcanism and erosion
impact cratering and erosion
impact cratering and volcanism
tectonics and erosion
volcanism and tectonics
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Correct
The most obvious features of the southern highlands are the many impact craters, but a close examination shows that many of them have been
“smoothed out,” indicating erosion that has occurred over time.
Question 9
Part A
What do we mean by a runaway greenhouse effect?
ANSWER:
a greenhouse effect that starts on a planet but later disappears as gases are lost to space
a greenhouse effect that heats a planet so much that its surface rock melts
a process that heats a planet like a greenhouse effect, but that involves a completely different mechanism of heating that doesn't actually
involve greenhouse gases
a greenhouse effect that keeps getting stronger until all of a planet's greenhouse gases are in its atmosphere
Correct
Question 10
Learning Goal:
To use your understanding of the terrestrial planets in our solar system to predict properties of terrestrial planets in other solar systems.
Introduction. The diagram shows the size, orbital distance, and
rotation rate of a hypothetical planet around another star, which
we'll call Planet Z. Assume that Planet Z is a terrestrial planet
shaped by the same basic processes that shape the terrestrial
planets of our solar system and that it orbits a star of the same
type and age as the Sun.
Part A
Based on Planet Z's size, orbital distance, and rotation rate, which of the following properties is it likely to have?
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Check all that apply.
Hint 1. How does size affect the characteristics of a terrestrial world?
Large terrestrial worlds __________ than smaller terrestrial worlds.
ANSWER:
have higher surface temperatures
retain internal heat longer
have more erosion
Hint 2. How does orbital distance affect the characteristics of a terrestrial world?
Terrestrial worlds that are close to their star tend to have __________ than terrestrial worlds that are farther away.
ANSWER:
more erosion
higher surface temperatures
thicker atmospheres
Hint 3. How does rotation rate affect the characteristics of a terrestrial world?
Relatively rapid rotation is required for a world to have __________.
ANSWER:
an atmosphere
active volcanoes
strong winds and violent storms
ANSWER:
erosion due to liquid water
strong winds and violent storms
an atmosphere produced by outgassing
seasons
active volcanoes
a surface crowded with impact craters
polar ice caps
active tectonics
Correct
Continue on to explore why the planet has these characteristics.
Part B
You have found that Planet Z should have active tectonics and volcanism and an atmosphere produced by volcanic outgassing. What single factor
explains why the planet should have these characteristics?
Hint 1. How does size affect the characteristics of a terrestrial world?
Large terrestrial worlds __________ than smaller terrestrial worlds.
ANSWER:
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retain internal heat longer
have more erosion
have higher surface temperatures
Hint 2. How does orbital distance affect the characteristics of a terrestrial world?
Terrestrial worlds that are close to their star tend to have __________ than terrestrial worlds that are farther away.
ANSWER:
higher surface temperatures
thicker atmospheres
more erosion
Hint 3. How does rotation rate affect the characteristics of a terrestrial world?
Relatively rapid rotation is required for a world to have __________.
ANSWER:
active volcanoes
an atmosphere
violent weather and storms
ANSWER:
has a slow rotation rate.
Planet Z closely orbits its star.
lacks axis tilt.
has a large size for a terrestrial planet.
Correct
Large size means more internal heat. This internal heat drives active tectonics and volcanism, which is the source of outgassing.
Part C
In Part A, you found that Planet Z should not have polar ice caps or liquid water. What single change to Planet Z's characteristics would allow it to
have these things?
Hint 1. How does size affect the characteristics of a terrestrial world?
Large terrestrial worlds __________ than smaller terrestrial worlds.
ANSWER:
have higher surface temperatures
have more erosion
retain internal heat longer
Hint 2. How does orbital distance affect the characteristics of a terrestrial world?
Terrestrial worlds that are close to their star tend to have __________ than terrestrial worlds that are farther away.
ANSWER:
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higher surface temperatures
thicker atmospheres
more erosion
Hint 3. How does rotation rate affect the characteristics of a terrestrial world?
Relatively rapid rotation is required for a world to have __________.
ANSWER:
active volcanoes
an atmosphere
violent weather and storms
ANSWER:
a smaller size
a larger size
a greater distance from its star
a larger axis tilt
Correct
The planet is too hot for liquid water or ice, so moving it farther from its star would allow it to cool down. If it cooled enough—but not too much—it
could have surface liquid water and ice caps.
Part D
In Part A, you found that Planet Z should not have strong winds and violent storms. What single change to Planet Z's characteristics would cause it to
have strong winds and violent storms?
Hint 1. What are the general requirements for strong winds and violent storms?
If a planet has an atmosphere, the most important factor determining the strength of its surface winds is its __________.
ANSWER:
rotation rate
distance from its star
axis tilt
ANSWER:
a faster rotation rate
a larger axis tilt
a smaller size
a greater distance from its star
Correct
The basic requirements for strong winds and violent storms are an atmosphere and relatively rapid rotation. An atmosphere is necessary to have
wind of any type, while rotation is necessary to create the forces (in particular, the Coriolis force) that tend to drive winds on a planet's surface.
Storms will be even stronger if there is also evaporation of surface water.
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Chapter 7 Homework
Part E
In Part A, you found that Planet Z should not have seasons. What single change to Planet Z's characteristics would cause it to have seasons?
Hint 1. What causes seasons on Earth?
The most important factor in the existence of seasons on Earth is Earth's __________.
ANSWER:
rotation rate
distance from the Sun
axis tilt
ANSWER:
a greater distance from its star
a faster rotation rate
a smaller size
a larger axis tilt
Correct
Seasons are caused primarily by axis tilt, so a planet without axis tilt is not expected to have seasons (unless it has a highly elliptical orbit).
Question 11
Choose the best answer.
Part A
The oxygen in Earth’s atmosphere was released by
ANSWER:
volcanic outgassing.
the CO2 cycle.
life.
Correct
Question 12
Part A
What is the importance of the carbon dioxide (CO2) cycle?
ANSWER:
It will prevent us from suffering any consequences from global warming.
It allows for an ultraviolet­absorbing stratosphere.
It regulates the carbon dioxide concentration of our atmosphere, keeping temperatures moderate.
It makes the growth of continents possible.
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Correct
Question 13
Part A
Earth has been gradually warming over the past few decades. Based on a great deal of evidence, scientists believe that this warming is caused by
_____.
ANSWER:
human activities that are increasing the concentration of greenhouse gases in Earth's atmosphere
the increase in forest fires during recent years
the human release of chemicals called CFCs into the stratosphere
the fact that our politicians spout a lot of hot air
Correct
Question 14
Part A
Based on all we know about the terrestrial worlds, what single factor appears to play the most important role in a terrestrial planet's geological destiny?
ANSWER:
its distance from the Sun
whether or not it has liquid water
its size
its composition
Correct
Score Summary:
Your score on this assignment is 48.9%.
You received 18.09 out of a possible total of 37 points.
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