Deck 8: Earth Materials As Time Keepers

Question 1

What is the composition of Earth's crust?

A) oceanic: basalt and gabbro; continental: felsic and mafic rocks
B) oceanic: basalt; continental: felsic
C) oceanic: felsic and mafic rocks; continental: mafic rocks
D) oceanic: mafic rocks with some gabbro; continental: felsic rocks with some basalt

Answer 1

A

Question 2

How does a seismograph work?

A) Sensitive triggers record digital signals and change them into binary so computers can analyze the data.
B) Fluid-filled sensors register shaking signals and feed them to recorders.
C) Rotating drums are marked by pens when Earth shakes.
D) Infrared movement sensors are wired to an inverter that changes the signals to binary so computers can analyze the data.

Answer 2

C

Question 3

Choose the option that puts the waves in order from slowest to quickest.

A) P-waves, S-waves, surface waves
B) S-waves, P-waves, surface waves
C) surface waves, P-waves, S-waves
D) surface waves, S-waves, P-waves

Answer 3

D

Question 4

What was the reason for installing a worldwide network of seismometers in the 1950s and 1960s?

A) to save human lives by predicting volcanic eruptions and earthquakes
B) to study plate tectonic theory
C) to monitor underground nuclear bomb testing
D) to study mine blasts

Question 5

What process explains the appearance of a mountain range of gabbro and basalt in a region largely covered with limestone?

A) The limestone formed at the bottom of the sea and the gabbro and basalt were pushed up by tectonic action afterward.
B) The limestone formed at the bottom of the sea and the gabbro and basalt, which formed in a river valley after the limestone, were pushed up to the surface.
C) The gabbro and basalt formed by igneous processes, and the limestone formed on the lower areas after the gabbro and basalt were pushed into a mountain range.
D) The limestone formed at the bottom of the sea and the gabbro and basalt formed by volcanic action afterward.

Question 6

A mountaintop is made of limestone overlying a layer of basalt. What would be the origin of this mountain?

A) The limestone would have formed by sediment in a river valley where the river was flowing over basalt.
B) The limestone would have formed by volcanic outflow and the basalt would have been part of the volcano.
C) The limestone would have formed at the bottom of an ocean and the basalt would have been part of the oceanic crust.
D) The basalt would have formed under metamorphosis by the pressure of the limestone that formed by sedimentation on top of it.

Question 7

X-rays are not used to study the geology of Earth. Why?

A) X-rays only penetrate living flesh.
B) Mineral matter is not transparent to X-rays.
C) X-rays do not extend to required distances of study.
D) X-rays do not produce three-dimensional images.

Question 8

Where is water movement the greatest in an ocean wave?

A) at the surface
B) 1 m below the surface
C) 10 m below the surface
D) 15 m below the surface

Question 9

At what depth do diamonds form in Earth?

A) 3.6 km
B) 8 km
C) 50 km
D) 150 km

Question 10

Waves are considered elastic because

A) they bounce back.
B) they do not permanently deform the water.
C) they are cyclical.
D) they do permanently deform the water.

Question 11

Which fact is not important when using earthquake waves to study Earth's interior?

A) Wave velocity depends on the medium.
B) Body waves penetrate deep into Earth.
C) Seismic stations are placed in many locations on Earth's surface.
D) Surface waves rarely penetrate deeply into the Earth.

Question 12

Scientists have estimated the density of Earth

A) by averaging the density of several hundred crust samples.
B) by measuring the wobbly rotation of Earth on its axis.
C) by calculating its interaction with nearby celestial objects.
D) by taking a drilling core and averaging the density of those rocks over the depth.

Question 13

Which is not a method that geologists use to study Earth's interior?

A) They infer the interior composition at deep levels from calculations of Earth's density.
B) They construct images of the interior using calculations of energy from earthquakes.
C) They use ultrasound, X-rays, infrared, and SONAR imaging to get three-dimensional images of rocks at depth.
D) They analyze core samples from drilled boreholes.

Question 14

Due to the nature of the movement of a wave, which type of wave cannot move through gases or liquids?

A) P-waves
B) S-waves
C) body waves
D) surface waves

Question 15

Approximately what percentage of Earth's radius have geologists studied to date?

A) 1%
B) 5%
C) 10%
D) 90%

Question 16

On average, how frequent are earthquakes?

A) hundreds per day
B) hundreds per year
C) thousands per day
D) thousands per year

Question 17

What is a similarity between oceanic and continental crust?

A) density
B) depth
C) composition of the mantle underneath
D) composition of the crust

Question 18

Geologists have not studied the composition of the oceanic crust by

A) dragging buckets along the floor to collect sediment and rocks.
B) studying the contents of drill holes.
C) examining aboveground mountain ranges.
D) analyzing earthquake data.

Question 19

Due to the nature of the movement of a wave, which wave produces the most earthquake damage?

A) P-waves
B) S-waves
C) body waves
D) surface waves

Question 20

A P-wave travels 48 km in 8 seconds. What is its velocity?

A) 6 km/s
B) 40 km/s
C) 56 km/s
D) 384 km/s

Question 21

Which of the following is not a common way to define the distance between an earthquake and a seismometer that records it?

A) by surface distance around Earth
B) by angular distance to a satellite
C) by angular distance to Earth's center
D) by straight-line distance through Earth

Question 22

Which region currently presents the most mysteries to scientists?

A) the low velocity zone in the upper mantle
B) the transition zone
C) the lowermost mantle
D) discontinuities at 410 and 660 km

Question 23

The curiously low seismic velocities observed in some places above the core-mantle boundary might be explained by

A) a small degree of melting in that area.
B) an anomalous rock type in that area.
C) a magnetic belt of rock in that area.
D) increased density in that area.

Question 24

Which process does not heat the inside of Earth?

A) radioactive decay of elements in the mantle and crust
B) crystallization of iron in the core
C) pressure applied by the weight of oceans
D) volcanic action

Question 25

Which two elements form most of Earth's core?

A) iron and nickel
B) iron and peridotite
C) iron and sulfur
D) iron and silicon

Question 26

Choose the option that puts the following steps in the correct sequence. 1. An electric sensor records the signal's travel time. 2. A transducer changes the signal into a thump on the rock. 3. An electrical signal is delivered. 4. The wave travels through the rock.

A) 4, 2, 3, 1
B) 3, 4, 1, 2
C) 3, 2, 4, 1
D) 4, 1, 2, 3

Question 27

A student comments, "The shadow zone is an area where waves cannot travel because it is a thick layer of liquid at the boundary of the mantle and the outer core." Evaluate this statement.

A) Actually, it was the boundary of the inner core that was discovered with this method.
B) It is correct that waves cannot travel in liquid.
C) P-waves refract at the shadow zone. S-waves are stopped.
D) The shadow zone refers to the whole outer core, not just the boundary.

Question 28

Which property of waves has been most important in allowing seismologists to identify the boundaries of the inner core/outer core and the outer core/mantle?

A) wave reflection
B) wave amplitude
C) wave velocity
D) wave refraction

Question 29

What evidence led scientists to believe that waves travel at a greater velocity inside Earth?

A) Studies of earthquake signals via sensors located deep inside drill holes prove it.
B) Refraction of energy waves is most efficient at shallower depths.
C) Refraction of energy waves is most efficient along short paths.
D) Average velocity is faster when the seismograph is farther from the focus of the earthquake.

Question 30

Which Earth section creates the most heat from radioactivity?

A) the oceanic crust
B) the continental crust
C) the core
D) the mantle

Question 31

A student concludes, "The transition zone is where minerals change from peridotite in the upper mantle to higher-pressure minerals by reconfiguration of atoms." Evaluate this statement.

A) It is true.
B) It is false. The transition zone is a place where mineral composition changes completely.
C) It is false. The transition zone is a place of higher density and pressure that interrupts the velocity of seismic waves.
D) It is true, except the minerals change from basalt to peridotite.

Question 32

Which of the following is not a reason that scientists have inferred that the core consists mostly of iron?

A) Iron is the only common element that accounts for the high density of the core.
B) Liquid iron in the core can explain Earth's magnetic field.
C) Molten iron's typical movement accounts for the wobbly rotation of Earth on its axis.
D) Some meteorites consist mostly of iron and appear to be likely analogs for planet cores.

Question 33

An electrical signal is delivered to a transducer that changes the signal into a thump on a rock. As the wave travels through the rock, an electric sensor records the signal's travel time. What does this experiment help scientists to calculate?

A) the force of a wave
B) the magnitude of a wave
C) the effect of a medium on wave travel
D) the velocity of a wave

Question 34

Which factors pertaining to rock type affect wave velocity through the material?

A) degree of metamorphism and water content
B) pressure and density
C) mineral abundance and pore space
D) temperature and water content

Question 35

What is the approximate depth of the liquid outer core, given the inferences of depth of the core-mantle boundary and the inner-outer core boundary?

A) 2900 km
B) 2255 km
C) 5155 km
D) 6371 km

Question 36

A considerable variation in seismic wave velocity in the crust occurs because

A) there are different types of rocks in the crust.
B) waves move slower the deeper they travel.
C) waves move faster the deeper they travel.
D) oceans, caves, karst regions, and underground waterways inhibit wave movement.

Question 37

Which factor has the least effect on the shape of the overall geothermal gradient?

A) loss of heat at the surface to the hydrosphere, atmosphere, and space
B) increasing temperature with compression of rock at high pressure
C) type and composition of rock in the mantle
D) heating of the lower mantle by the hotter core

Question 38

Which of the following is not a reason that temperature increases with depth?

A) The outer surface of the planet cools by radiating heat.
B) Denser inner rock types hold more heat than less dense crustal rocks.
C) Heat conducts outward from the core into the lower mantle.
D) Rocks heat up when pressure increases.

Question 39

Which of the following is not an abundant radioactive element within Earth?

A) thorium
B) uranium
C) potassium
D) curium

Question 40

Two rock types that have been studied in the laboratory to determine likely temperatures at depth in the mantle are

A) peridotite and olivine.
B) diamond-bearing rocks and olivine.
C) peridotite and diamond-bearing rocks.
D) basalt and peridotite.

Question 41

A paper or digital record of surface and body wave motion is called a

A) seismogram.
B) seismologist.
C) seismic wave.
D) seismometer.

Question 42

Secondary (S) waves have all of the following characteristics except

A) causes alternating squeezing and stretching of the material as the wave passes.
B) body wave.
C) arrives second at seismic stations.
D) can't pass through gases and liquids.

Question 43

Stretching clay and having it not return it to its original shape when the force is removed is an example of ________ deformation.

A) elastic
B) plastic
C) clay
D) brittle

Question 44

At conditions within Earth's mantle, the increase in mineral density due to increasing pressure is ________ the decrease in mineral density due to increasing pressure.

A) greater than
B) less than
C) equal to
D) unrelated to

Question 45

The body waves that can only pass through solids are

A) primary (P) waves.
B) tertiary (T) waves.
C) secondary (S) waves.
D) quaternary (Q) waves.

Question 46

The location on Earth's surface, directly above the focus, is called the

A) tsunami.
B) seismic center.
C) epicenter.
D) surface focus.

Question 47

The average Earth density is ________ the mantle density.

A) unrelated to
B) equal to
C) less than
D) greater than

Question 48

The location of an earthquake within Earth is called the

A) focus.
B) epicenter.
C) seismic center.
D) tsunami.

Question 49

Stretching a rubber band and then returning it to its original shape is an example of ________ deformation.

A) plastic
B) elastic
C) brittle
D) aural

Question 50

A change in direction of a body wave when it crosses a boundary between layers with different physical properties is called seismic

A) absorption.
B) reflection.
C) refraction.
D) velocity.

Question 51

Primary (P) waves have all of the following characteristics except

A) arrives first at seismic stations.
B) body wave.
C) causes alternating squeezing and stretching of the material as the wave passes.
D) can't pass through gases and liquids.

Question 52

The only way to study the composition and mineralogy of oceanic crustal rocks is by drilling or dredging.

Question 53

An instrument designed to detect, amplify, and record surface and body wave motion is called a

A) seismogram.
B) seismologist.
C) seismic wave.
D) seismometer.

Question 54

Earthquake body wave records allow scientists to construct an image of Earth's interior.

Question 55

Oceanic crustal rocks and continental crustal rocks occurring at the same depth have similar compositions but different mineralogies.

Question 56

Which rock type does not have a strong affinity for radioactive elements?

A) felsic igneous
B) mafic igneous
C) sedimentary
D) metamorphic

Question 57

The relationship between predicted and actual P- and S-wave arrival times support the hypothesis that P- and S-wave velocities are the same throughout Earth.

Question 58

Earth exhibits a gradual inward transition from low-density to high-density rock.

Question 59

Earth's continental crust is ________ thick.

A) 25 - 50 km
B) 37.5 km
C) 50 km
D) 25 km

Question 60

The average radius of Earth is ________ km.

A) 6350
B) 6371
C) 6378
D) 6357

Question 61

Other than natural seismic waves, what kinds of things create seismic waves that scientists study?

Question 62

There is more than one type of crust on Earth. What are they? How do they differ?

Question 63

What is one additional approach, besides the study of the baseball, that geologists use to gain knowledge about Earth's interior?

A) Geologists infer the interior composition at deep levels from calculations of Earth's density.
B) Geologists collect and study data from volcanoes, mainly about the lava, to gain knowledge about the interior.
C) Geologists use energy from earthquakes to construct images of Earth's interior.
D) Geologists go as far into the center of the earth as possible by exploring in drilled boreholes and mines, going as deep as possible.

Question 64

Most earthquake destruction results from

A) primary (P) waves.
B) secondary (S) waves.
C) surface waves.
D) acoustic waves.

Question 65

What is the correct order of the layers of the Earth?

A) mantle, continental crust, oceanic crust, inner, and outer core
B) continental crust, oceanic crust, outer core, mantle, inner core
C) continental crust, oceanic crust, mantle, outer core, inner core
D) outer core, oceanic crust, continental crust, mantle, inner core

Question 66

What kind of waves are P and S waves?

A) surface waves
B) interior waves
C) body waves
D) sound waves

Question 67

What was the astronomer Eratosthenes responsible for?

A) calculating that a rotating planet would not be perfectly spherical
B) determining the mass of Earth
C) determining that the Earth has a distinct concentration of high-density material near the center
D) using simple surveying and measurements of shadows in sunlight to estimate Earth's size

Question 68

Geologists use energy from earthquakes to construct images of Earth's interior.

Question 69

The focus is the point on the surface directly below the epicenter (location within Earth) of an earthquake.

Question 70

What did Sir Isaac Newton do during the seventeenth century?

A) calculate that a rotating planet would not be perfectly spherical
B) determine the mass of Earth
C) determine that the Earth has a distinct concentration of high-density material near the center
D) use simple surveying and measurements of shadows in sunlight to estimate Earth's size

Question 71

The Mohorovicic discontinuity or Moho corresponds to the boundary between

A) core and crust.
B) mantle and core.
C) mantle and crust.
D) oceanic crust and continental crust.

Question 72

P- and S-wave shadow zones begin at locations that are 98 degrees around the globe in all directions from an epicenter which corresponds to a depth near the boundary between

A) mantle and crust.
B) mantle and core.
C) core and crust.
D) oceanic crust and continental crust.

Question 73

"How fast do seismic waves move through different rocks and under different conditions?"

Question 74

The Mohorovicic discontinuity or Moho was discovered based on

A) chemical differences between felsic and mafic rocks.
B) the S-wave shadow zone.
C) a sharp change in seismic velocities.
D) mineralogical data from drill holes.

Question 75

Seismometers are extremely sensitive instruments designed to detect, amplify, and record surface and body wave motion, some of which may not be felt by humans.

Question 76

The (P) is (P) waves stands for:

A) physical
B) primary
C) productive
D) pulsing

Question 77

The (S) in (S) waves stands for:

A) slow
B) speedy
C) secondary
D) seismic

Question 78

Regions where seismometers do not record P and/or S waves are called

A) aseismic regions.
B) nonseismic zones.
C) seismic gaps.
D) shadow zones.

Question 79

Geologists infer the interior composition at deep levels from calculations of Earth's density.

Question 80

The ________ is solid and very iron rich.

A) crust (continental)
B) crust (oceanic)
C) mantle
D) core (outer)
E) core (inner)