Conceptual Quiz
Part A
The cores of the terrestrial worlds are made mostly of metal because ______.
Hint A.1
Study Section 9.1
ANSWER:

the terrestrial worlds as a whole are made mostly of metal. the core contained lots of radioactive elements that decayed into metals. over billions of years, convection gradually brought dense metals downward to the core. metals sunk to the centers a long time ago when the interiors were molten throughout.
Part B
Which of the following is NOT generally true of all the terrestrial world lithospheres?
Hint B.1
Study Section 9.1
ANSWER:

The thickness of the lithosphere depends on interior temperature, with cooler interiors leading to thicker lithospheres. The lithosphere is broken into a set of large plates that float upon the softer rock below. The lithosphere extends from somewhere in the mantle all the way to the surface. Rock in the lithosphere is stronger than rock beneath it.
Part C
Which internal heat source still generates heat within the terrestrial worlds today?
Hint C.1
Study Section 9.1
ANSWER:

Heat from differentiation Heat of accretion. Heat from radioactive decay. Heat from convection.
Part D
The reason that small planets tend to lose interior heat faster than larger planets is essentially the same as the reason that:
Hint D.1
Study Section 9.1
ANSWER:

a large baked potato takes longer to cool than a small baked potato. gas bubbles form and rise upward in boiling water. Earth contains more metal than the Moon. thunderstorms tend to form on hot summer days.
Part E
Recent evidence suggests that Mars, like Earth, once had a stronger magnetic field. Assuming this is true, which of the following could explain why Mars lacks a global magnetic field like that of Earth?
Hint E.1
Study Section 9.1, 9.4
ANSWER:

Because Mars's interior is cooler than Earth's, its liquid core layer may not be undergoing convection. Mars is too far from the Sun to have a global magnetic field. The Martian core is made of rock, while Earth's core is made of metal. Mars rotates much slower than the Earth.
Part F
You discover an impact crater that is 10 kilometers across. Which of the following can you conclude?
Hint F.1
Study Section 9.2
ANSWER:

It was created by the impact of an object about 1 kilometer across. It was created within the past 10 million years. It was created within the past 1 billion years. It was created by the impact of an object about 10 kilometers across.
Part G
Most of the Moon's surface is densely covered with craters, but we find relatively few craters within the lunar maria. What can we conclude?
Hint G.1
Study Section 9.2
ANSWER:

The maria formed within the past 1 billion years. The maria formed after the heavy bombardment ended. Erosion affects the maria more than it affects other regions of the Moon. The regions of the maria were hit by fewer impacts than the densely cratered regions.
Part H
Which of the following is the underlying reason why Venus has little wind erosion?
Hint H.1
Study Section 9.2, 9.5
ANSWER:

Its thick atmosphere. Its small size. Its slow rotation. Its relatively close distance to the Sun.
Part I
Which of the following best describes the geological histories of the Moon and Mercury?
Hint I.1
Study Section 9.3
ANSWER:

Impact cratering is the only major geological process that has affected their surfaces. Early in their histories, they suffered many impacts and experienced some volcanism and tectonics, but they now have little geological activity at all. All four geological processes were important in their early histories, but only impact cratering still reshapes their surfaces today. Impact cratering shaped these worlds early in their histories. Then, during the past few million years, they were reshaped by episodes of volcanism and tectonics.
Part J
Many scientists suspect that Venus has a stronger and thicker lithosphere than Earth. If this is true, which of the following could explain it?
Hint J.1
Study Section 9.5
ANSWER:

The high surface temperature that has "baked out" all the liquid water from Venus's crust and mantle. The smaller size of Venus, which has allowed it to lose much more internal heat than Earth. The apparent lack of plate tectonics on Venus. The slow rotation of Venus.
Part K
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?
Hint K.1
Think of all you learned in this chapter, especially Figure 9.15.
ANSWER:

Its composition. Its size. Its distance from the Sun. Whether or not it has liquid water.
Part L
The choices below describe four hypothetical planets. Which one would you expect to have the hottest interior? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.)
Hint L.1
Consider all that you've learned in this chapter.
ANSWER:

Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours. Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months. Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours. Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days.
Part M
The choices below describe four hypothetical planets. Which one's surface would you expect to be most crowded with impact craters? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.)
Hint M.1
Consider all that you've learned in this chapter.
ANSWER:

Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days. Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours. Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months. Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours.
Part N
The choices below describe four hypothetical planets. Which one would you expect to have the most features of erosion? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.)
Hint N.1
Consider all that you've learned in this chapter.
ANSWER:

Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours. Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months. Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days. Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours.
Part O
All the following statements about Venus are true. Which one offers evidence of a global repaving about a billion years ago?
Hint O.1
Study Section 9.5
ANSWER:

Venus has relatively few impact craters, and they are distributed fairly evenly over the entire planet. Venus's largest features are three elevated regions that look somewhat like continents. Venus has many circular features, called coronae, which appear to be tectonic in origin. Venus appears to lack any water that could lubricate the flow of rock in its crust and mantle.
Part P
What are the two geological features that appear to set Earth apart from all the other terrestrial worlds?
Hint P.1
Study Section 9.6
ANSWER:

Shield volcanoes and plate tectonics. Mantle convection and a thick atmosphere. Plate tectonics and widespread erosion. Significant volcanism and tectonics.
Part Q
What's the fundamental reason that Mars, unlike the Earth, has become virtually geologically dead?
Hint Q.1
Study Section 9.4
ANSWER:

Mars' rapid rotation compared to the Earth. Mars is farther from the Sun than the Earth. Mars is closer to the Sun than the Earth. Its large size compared to the Earth. Mars' slow rotation compared to the Earth. Its small size compared to Earth.
Part R
Why are there fewer large impact craters on the Earth's seafloor than on the continents?
Hint R.1
Study Section 9.6
ANSWER:

Erosion erases impact craters must faster on the ocean bottom than on land. The seafloor crust is younger than the continental crust, so has had less time in which to suffer impacts. Most impacts occur on the land. The oceans slow large impactors and prevent them from making craters.
Part S
Why is Earth's continental crust lower in density than seafloor crust?
Hint S.1
Study Section 9.6
ANSWER:

Continental crust comes from Earth's inner core while seafloor crust comes from the outer core. Continental crust is made from melting seafloor crust near subduction zones, but only the lowest density material melts and erupts to the surface. Continental crust comes from volcanoes while seafloor crust comes from geysers. Continental crust is made from volcanic rock called basalt, which is lower in density than what the seafloor crust is made from.
Part T
Which two factors are most important to the existence of plate tectonics on Earth?
Hint T.1
Study Section 9.6
ANSWER:

The existence of life and oxygen in the atmosphere. Oxygen in the atmosphere and mantle convection. Mantle convection and a thin lithosphere. Earth's liquid outer core and solid inner core.