Ch. 7A: The Earth and Terrestrial Planets

What observational evidence supports the idea that Mercury once shrank by some 20 kilometers in radius?

the presence of many long, tall cliffs

The two most important processes in heating the interiors of the terrestrial worlds are __________.

(1) heat deposited by the process of formation; (2) heat released by radioactive decay

Based solely on an understanding of the greenhouse effect (as displayed in the figure), which one of the following statements is true?

We should expect an increase in the greenhouse gas concentration to lead to global warming.

Which of the following statements about our solar system's terrestrial worlds are true?

Their interiors all have a core, mantle, and crust. They are all of nearly the same age. They are all made primarily of rock and metal.

In general, which of the following are affected by a magnetic field?

charged particles or magnetized materials (such as iron)

4. Australia is composed of relatively old and thick continental crust.

continental crust

Shown below are the four terrestrial planets of our solar system. Assume that all the planets started out equally hot inside. Rank the planets based on their expected cooling rates, from fastest cooling to slowest cooling.

fastest cooling- slowest Mercury, Mars, Venus, Earth goes from smallest to largest

The processes responsible for virtually all surface geology are _________.

impact cratering, volcanisms, tectonics, and erosion

5. The extremely deep ocean Marianas Trench is a result of subduction.

subduction

Earth has a relatively strong magnetic field, but Mars does not. Which of the following probably explains why Mars lacks a strong magnetic field today?

Its core is too cool for convection.

Shown following are three terrestrial planets of our solar system. Rank the planets based on the amount of time the surface of the planet has had a moderate to high level of volcanic/tectonic activity, from longest to shortest.

Longest Time- Shortest time Earth, Mars, Mercury Also has to do with size

Earth's temperature remains fairly steady, which means that Earth must return nearly the same amount of energy to space that it receives from the Sun. In what form(s) does Earth return most of this energy to space?

infrared light emitted by the surface and atmosphere visible light reflected by the surface visible light reflected by clouds

The greenhouse effect raises Earth's surface temperature (from what it would be otherwise) because the infrared light radiated by Earth's surface __________.

is absorbed by greenhouse gases, slowing the escape of this energy to space

How does the amount of heat released in a planet's interior by radioactive decay change with time?

it drops off with time

The existence of a core-mantle-crust interior structure tells us that a world __________.

once had a molten interior

Which heat source continues to contribute to Earth's internal heat?

radioactive decay

According to scientists, the naturally occurring greenhouse effect makes Earth about 31∘C warmer than it would be if there were no greenhouse gases in our atmosphere. How do scientists "know" what Earth's temperature would be without greenhouse gases?

They calculate this temperature from Earth's reflectivity and distance from the Sun.

Seismic studies on Earth reveal a "lost continent" that held great human cities just a few thousand years ago but is now buried beneath the Atlantic seafloor.

This is not plausible. Plates move only a few centimeters per year, so a continent could not be subducted in a few thousand years. Neither could erosional processes bury a continent on the time scale of human civilization.

All of the following statements are true. Which one provides strong observational support for the claim that greenhouse gases make a planet warmer than it would be otherwise?

Venus has a higher average temperature than Mercury.

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 large-scale processes affecting the structure of the planetary crust), most responsible for the feature described. Match the geographic feature to the appropriate geologic process.

Volcanism smooth surfaces of the lunar mariaBig Island of HawaiiMars's Olympus Mons Impact cratering old surface features of the lunar highlands Erosion Earth's Grand Canyon Tectonics current locations of Earth's continentsMars's Valles MarinerisMercury's many long, tall cliffs

Which of the following is the most basic definition of a greenhouse gas?

a gas that absorbs infrared light

Suppose we use a baseball to represent Earth. On this scale, the other terrestrial worlds (Mercury, Venus, the Moon, and Mars) would range in size approximately from that of _________.

a golf ball to a baseball

In general, what kind of terrestrial planet would you expect to have the thickest lithosphere?

a small planet

Suppose we represent Earth with a basketball. On this scale, most of the air in Earth's atmosphere would fit in a layer that is _________.

about the thickness of a sheet of paper

Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, make Earth warmer than it would be otherwise because these gases __________.

absorb infrared light emitted by the surface

7. The earthquakes that occur in Southern California generally occur above a fault.

fault

Old Faithful Geyser at Yellowstone National Park in the United States acquires its energy from a hot spot.

hot spot

Scientists can estimate the age of a planetary surface by counting __________.

impact craters

6. Seafloor crust found in the Atlantic Ocean between North America and Europe is composed of dense and relatively young rock.

seafloor crust

1. The slowly increasing distance between South America and Africa is due to seafloor spreading.

seafloor spreading.

Layered sedimentary rock exposed by erosion can be seen when looking at the Grand Canyon in the United States.

sedimentary rock

Which of a planet's fundamental properties has the greatest effect on its level of volcanic and tectonic activity?

size

What happens to the energy that the ground absorbs in the form of visible sunlight?

It is returned upward in the form of infrared light.

On a cloudless day, what happens to most of the visible light headed toward Earth?

It reaches Earth's surface, where some is reflected and some is absorbed.

Each of the following statements is best associated with one of the four major geological processes. Drag each statement into the correct bin for its associated process.

Impact Cratering Mostly occurred during heavy bombardment.Affected all solid worlds similarly. Volcanism Created the smooth lunar maria. Erased virtually all craters on Io.Responsible for the existence of Earth's atmosphere and oceans. Tectonics On Earth, involves motion of plates.Includes surface compression that builds mountains. Erosion Includes features sculpted by wind.

What do we conclude if a planet has few impact craters of any size?

Other geological processes have wiped out craters.

As a general rule, smaller planets __________ than larger planets.

cool more rapidly

How many of the five terrestrial worlds are considered "geologically dead"?

two

The energy that warms Earth's surface comes primarily in the form of __________.

visible light from the Sun