Chapter 9 Homework

Spacecraft have landed on all the terrestrial worlds except A) Venus. B) Mercury. C) Mars. D) Moon.

B) Mercury.

Which of the following most likely explains why Venus does not have a strong magnetic field? A) It has too thick an atmosphere. B) It is too close to the Sun. C) It is too large. D) Its rotation is too slow. E) It does not have a metallic core.

D) Its rotation is too slow.

Which of the following show evidence of ancient river beds? A) Mercury B) the Moon C) Venus D) Mars E) all of the above

D) Mars

Which of the following Mars surface features provides dramatic evidence that volcanism has played a role in shaping the surface of Mars? A) the polar caps B) the southern highlands C) Valles Marineris D) Olympus Mons

D) Olympus Mons

Which of the following best describes why the smaller terrestrial worlds have cooler interiors than the larger ones? A) They were cooler when they formed. B) They had more volcanic eruptions in the past, which released their internal heat. C) They have relatively fewer radioactive elements. D) They have relatively more surface area compared to their volumes. E) The smaller ones are farther from the Sun.

D) They have relatively more surface area compared to their volumes.

Which internal energy source produces heat by converting gravitational potential energy into thermal energy? A) differentiation B) accretion C) radioactivity D) both A and B E) all of the above

D) both A and B

What are the conditions necessary for a terrestrial planet to have a strong magnetic field? A) a molten metallic core only B) fast rotation only C) a rocky mantle only D) both a molten metallic core and reasonably fast rotation E) both a metal core and a rocky mantle

D) both a molten metallic core and reasonably fast rotation

How long, approximately, do geologists estimate it takes for the entire seafloor to be replaced due to plate tectonics? A) 200 million years B) 2 billion years C) 20 million years D) 2 million years E) longer than the age of the solar system

A) 200 million years

Why does Earth have the strongest magnetic field among the terrestrial worlds? A) It is the only one that has both a partially molten metallic core and reasonably rapid rotation. B) It is the most volcanically active world. C) It is by far the largest terrestrial world. D) It is the only one that has a metallic core. E) It rotates much faster than any other terrestrial world.

A) It is the only one that has both a partially molten metallic core and reasonably rapid rotation.

Rank the five terrestrial worlds in order of size from smallest to largest: A) Moon, Mercury, Mars, Venus, Earth. B) Mercury, Moon, Mars, Earth, Venus. C) Mercury, Moon, Venus, Earth, Mars. D) Moon, Mercury, Venus, Earth, Mars. E) Mercury, Venus, Earth, Moon, Mars.

A) Moon, Mercury, Mars, Venus, Earth.

The main process by which heat flows upward through the lithosphere is A) conduction. B) accretion. C) differentiation. D) radiation. E) convection.

A) conduction.

Which two properties are most important in determining the surface temperature of a planet? A) distance from the Sun and atmosphere B) internal temperature and atmosphere C) size and chemical composition D) size and atmosphere E) composition and distance from the Sun

A) distance from the Sun and atmosphere

Valles Marineris is a A) large canyon on Mars. B) vast plain on Mars. C) huge series of cliffs on Mercury. D) large valley on the Moon. E) large canyon on Venus.

A) large canyon on Mars

Which of the following does not have a major effect in shaping planetary surfaces? A) magnetism B) volcanism C) erosion D) tectonics E) impact cratering

A) magnetism

The polar caps on Mars are composed of A) mostly solid carbon dioxide and some water ice. B) mostly water ice and some solid carbon dioxide. C) pure water ice. D) pure solid carbon dioxide. E) There are no polar caps on Mars.

A) mostly solid carbon dioxide and some water ice.

The geysers and hot springs of Yellowstone National Park result from A) plumes of hot mantle rising in a hot spot within a plate. B) a fault. C) plates that have slipped sideways relative to each other, creating a fault. D) thin continental crust separating and creating a rift valley. E) a plate that has run up against an existing continental plate.

A) plumes of hot mantle rising in a hot spot within a plate.

Which internal energy source is the most important in continuing to heat the terrestrial planets today? A) radioactivity B) tidal heating C) accretion D) differentiation E) all of the above

A) radioactivity

Olympus Mons is a A) shield volcano on Mars. B) stratovolcano on the Moon. C) shield volcano on Venus. D) large lava plain on the Moon. E) stratovolcano on Mercury.

A) shield volcano on Mars.

What is differentiation in planetary geology? A) the process by which gravity separates materials according to density B) any process by which one part of a planet's surface evolves differently from another part of the same planet's surface C) any process by which a planet evolves differently from its moons D) any process by which a planet's surface evolves differently from another planet's surface E) the process by which different types of minerals form a conglomerate rock

A) the process by which gravity separates materials according to density

The relatively few craters that we see within the lunar maria A) were formed by impacts that occurred after those that formed most of the craters in the lunar highlands. B) are sinkholes that formed when sections of the maria collapsed. C) are volcanic in origin, rather than from impacts. D) were created by the same large impactor that led to the formation of the maria. E) were formed by impacts that occurred before those that formed most of the craters in the lunar highlands.

A) were formed by impacts that occurred after those that formed most of the craters in the lunar highlands

Why does the Moon have a layer of powdery "soil" on its surface? A) Volatiles escaping from the Moon's interior bubble upward and make the soil. B) It's the result of gradual erosion by micrometeorites striking the Moon. C) The soil exists because the Moon accreted from powdery material after a giant impact blasted Earth. D) Large impacts shattered lunar rock to make this soil. E) The soil is the result of the same processes that make powdery sand on Earth.

B) It's the result of gradual erosion by micrometeorites striking the Moon.

Volcanism is more likely on a planet that A) is struck often by meteors and solar system debris. B) has high internal temperatures. C) doesn't have an atmosphere or oceans. D) is closer to the Sun.

B) has high internal temperatures.

When you zoom in on the section labeled "Southern Highlands," which geologic processes are most clearly evident? A) volcanism and erosion B) impact cratering and erosion C) impact cratering and volcanism D) tectonics and erosion E) volcanism and tectonics

B) impact cratering and erosion

Heat escapes from a planet's surface into space by thermal radiation. Planets radiate almost entirely in the wavelength range of the A) radio. B) infrared. C) visible. D) ultraviolet. E) none of the above

B) infrared.

Which of the following has virtually no effect on the structure of a planet? A) its composition B) its magnetic field C) its mass D) its size

B) its magnetic field

Which of the following describes volcanism? A) the excavation of bowl-shaped depressions by asteroids or comets striking a planet's surface B) the eruption of molten rock from a planet's interior to its surface C) the disruption of a planet's surface by internal stresses D) the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather

B) the eruption of molten rock from a planet's interior to its surface

What are the circumstances under which convection can occur in a substance? A) when the substance is subjected to a strong magnetic field B) when the substance is strongly heated from underneath C) when the substance is strongly shaken or disturbed by a strong wind D) when the substance is strongly cooled from underneath E) when dense material is being added to the substance

B) when the substance is strongly heated from underneath

How large is an impact crater compared to the size of the impactor? A) 100 times larger B) 1,000 times larger C) 10 times larger D) 10-20 percent larger E) the same size

C) 10 times larger

How did the lunar maria form? A) Volatiles escaping from the Moon's interior heated and eroded the surface in the regions of the maria. B) The giant impact that created the Moon left smooth areas that we call the maria. C) Large impacts fractured the Moon's lithosphere, allowing lava to fill the impact basins. D) The early bombardment created heat that melted the lunar surface in the regions of the maria. E) The maria are the result of gradual erosion by micrometeorites striking the Moon.

C) Large impacts fractured the Moon's lithosphere, allowing lava to fill the impact basins

How does seafloor crust differ from continental crust? A) Seafloor crust is thicker, older, and higher in density. B) Seafloor crust is thinner, older, and lower in density. C) Seafloor crust is thinner, younger, and higher in density. D) Seafloor crust is thicker, older, and lower in density. E) Seafloor crust is thicker, younger, and lower in density.

C) Seafloor crust is thinner, younger, and higher in density.

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? A) Abundant surface water is found in large, brownish pools inside craters. B) There are numerous small streams flowing with water. C) Surface water only exists as frozen ice. D) No surface water currently exists in any form.

C) Surface water only exists as frozen ice.

How fast do plates move on Earth? A) a few kilometers per century B) a few millimeters per century C) a few centimeters per year D) quite fast, but only during earthquakes E) about 1 mile per hour

C) a few centimeters per year

How have we been able to construct detailed maps of surface features on Venus? A) by studying Venus with powerful optical telescopes on spacecraft that were sent to orbit Venus B) by studying Venus from Earth with powerful telescopes C) by using radar from spacecraft that were sent to orbit Venus D) by making computer models of geological processes on Venus E) by landing spacecraft on the surface for close-up study

C) by using radar from spacecraft that were sent to orbit Venus

Which of the following does not provide evidence for water on Mars? A) dry riverbeds B) groupings of rocks that appear to have been deposited as in a flood C) canal structures observed by Percival Lowell D) eroded craters

C) canal structures observed by Percival Lowell

A planet is most likely to have tectonic activity if it has A) high surface gravity. B) a dense atmosphere. C) high internal temperature. D) low internal temperature. E) low surface gravity.

C) high internal temperature.

The terrestrial planet cores contain mostly metal because A) metals condensed first in the solar nebula and the rocks then accreted around them. B) convection carried the metals to the core. C) metals sank to the center during a time when the interiors were molten throughout. D) radioactivity created metals in the core from the decay of uranium. E) the entire planets are made mostly of metal.

C) metals sank to the center during a time when the interiors were molten throughout.

Mineral evidence shows that Earth's oceans have existed for A) several hundred million years. B) several billion years. C) over four billion years. D) several ten million years. E) millions of years.

C) over four billion years.

What type of stresses broke Earth's lithosphere into plates? A) internal temperature changes that caused the crust to expand and stretch B) impacts of asteroids and planetesimals C) the circulation of convection cells in the mantle, which dragged against the lithosphere D) volcanism, which produced heavy volcanoes that bent and cracked the lithosphere E) cooling and contracting of the planet's interior, which caused the mantle and lithosphere to be compressed

C) the circulation of convection cells in the mantle, which dragged against the lithosphere

Which of the following describes impact cratering? A) the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather B) the disruption of a planet's surface by internal stresses C) the excavation of bowl-shaped depressions by asteroids or comets striking a planet's surface D) the eruption of molten rock from a planet's interior to its surface

C) the excavation of bowl-shaped depressions by asteroids or comets striking a planet's surface

Which of the following describes erosion? A) the eruption of molten rock from a planet's interior to its surface B) the excavation of bowl-shaped depressions by asteroids or comets striking a planet's surface C) the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather D) the disruption of a planet's surface by internal stresses

C) the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather

Which of the following best describes convection? A) It is the process in which bubbles of gas move upward through a liquid of the same temperature. B) It is the process in which a liquid separates according to density, such as oil and water separating in a jar. C) It is the process in which warm material gets even warmer and cool material gets even cooler. D) It is the process in which warm material expands and rises while cool material contracts and falls. E) It is the process by which rocks sink in water.

D) It is the process in which warm material expands and rises while cool material contracts and falls.

What drives the motion of the tectonic plates on Earth? A) the Coriolis force B) lava flows in trenches along the sea floor C) tidal forces D) convection cells in the mantle E) Earth's magnetic field

D) convection cells in the mantle

When we say that a liquid has a high viscosity, we mean that it A) is very dark in color. B) conducts electricity. C) is very light in color. D) flows slowly like honey. E) is runny like water.

D) flows slowly like honey.

Ridges in the middle of the ocean are places where A) plates slip sideways relative to one another. B) one plate slides under another, returning older crust to the mantle. C) hot mantle material rises upward, creating volcanic islands. D) hot mantle material rises upward and spreads sideways, pushing the plates apart. E) plates push together, creating ocean mountain chains.

D) hot mantle material rises upward and spreads sideways, pushing the plates apart.

The Caloris Basin on Mercury covers a large region of the planet, but few smaller craters have formed on top of it. From this we conclude that A) erosion destroyed the smaller craters that formed on the basin. B) only very large impactors hit Mercury's surface in the past. C) the Caloris Basin was formed by a volcano. D) the Caloris Basin formed toward the end of the solar system's period of heavy bombardment. E) Mercury's atmosphere prevented smaller objects from hitting the surface.

D) the Caloris Basin formed toward the end of the solar system's period of heavy bombardment.

Which of the following regions was the result of plumes of hot mantle rising in a hot spot within a plate? A) the volcano Mount St. Helens B) Japan and the Philippines C) Alaska's Aleutian Islands D) the islands of Hawaii E) all of the above

D) the islands of Hawaii

Why is continental crust lower in density than seafloor crust? A) Continental crust is made from volcanic rock called basalt, which is lower in density than what the seafloor crust is made from. B) Seafloor crust is more compact due to the weight of the oceans, but it is made of the same material as the continental crust. C) Continental crust is made of rock, while seafloor crust has more metals. D) Continental crust is actually denser than seafloor crust. E) Continental crust is made from remelted seafloor crust and therefore only the lower-density material rises to form it.

E) Continental crust is made from remelted seafloor crust and therefore only the lower-density material rises to form it.

Which of the terrestrial worlds has the strongest magnetic field? A) Venus B) Mars C) the Moon D) Mercury E) Earth

E) Earth

Under what circumstances can differentiation occur in a planet? A) The planet must be geologically active, that is, have volcanoes, planetquakes, and erosion from weather. B) The planet must have an atmosphere. C) The planet must have a rocky surface. D) The planet must be made of both metal and rock. E) The planet must have a molten interior.

E) The planet must have a molten interior.

The three principal sources of internal heat of terrestrial planets are A) conduction, convection, and eruption. B) conduction, differentiation, and accretion. C) accretion, differentiation, and eruption. D) convection, differentiation, and eruption. E) accretion, differentiation, and radioactivity.

E) accretion, differentiation, and radioactivity.

What kind of surface features may result from tectonics? A) mountains B) cliffs C) volcanos D) valleys E) all of the above

E) all of the above

When we see a region of a planet that is not as heavily cratered as other regions, we conclude that A) the surface in the region is older than the surface in more heavily cratered regions. B) the planet formed after the age of bombardment and missed out on getting hit by leftover planetesimals. C) there is little volcanic activity to create craters. D) the planet is rotating very slowly and only one side was hit by impactors. E) the surface in the region is younger than the surface in more heavily cratered regions.

E) the surface in the region is younger than the surface in more heavily cratered regions

The magnetic and rotational north poles on Earth are the same. True False

False

Earth is the only planet in the solar system known to have plate tectonics. True False

True

Mars has virtually no magnetic field. True False

True