Deck 2: Plate Tectonics

Question 1

As early as the 1700s, scientists and observers noticed a remarkable coincidence of shape of the Atlantic coasts of Africa and .

A) North America
B) Australia
C) Asia
D) South America

Answer 1

D

Question 2

Japan is located along the " Pacific Ring of Fire " and experiences many earthquakes. The majority of  the earthquakes around Japan occur .

A) only on the east side of the island where the Pacific plate subducts
B) only on the west side of the island where the Eurasian plate subducts
C) near the Pacific spreading center
D) near the Mid-Atlantic ridge

Answer 2

A

Question 3

Scientists believe the breakup of Pangaea occurred about .

A) 1 million years ago
B) 25 million years ago
C) 200 million years ago
D) 750 million years ago

Answer 3

C

Question 4

If two oceanic plates collide and one is older and cooler (and therefore, denser) than the other, what will happen?

A) A deep trench will form.
B) Continental mountains will form.
C) A mid-ocean ridge will form.
D) A hot spot will form.

Question 5

What is the primary reason for the inside of Earth being hot?

A) No heat is being generated, but Earth's outer layers have prevented the escape of heat trapped during the planet's initial formation.
B) The decay of radioactive elements is creating heat in Earth's inner layers.
C) The nuclear process of fusing hydrogen into helium like that found in stars is at work in Earth's interior.
D) Huge quantities of oil and natural gas occasionally burn deep within Earth.

Question 6

Why was Alfred Wegener's idea of continental drift dismissed?

A) Someone else had already introduced his idea to the scientific community.
B) Many of his evidences did not support drifting continents.
C) Continents have not moved since Earth was created.
D) The evidence at the time seemed to suggest a solid mantle that did not allow drifting of continents to be possible.

Question 7

Buoyancy is the ability of an object to float in a fluid by .

A) weighing less than the water surrounding it
B) displacing a volume of water equal in weight to its own weight
C) having a lot of air within its body
D) displacing a volume of water which weighs slightly less than its own weight

Question 8

California's San Andreas fault is which type of plate boundary?

A) divergent plate boundary
B) transform plate boundary
C) ocean - continent convergent plate boundary
D) continent - continent convergent plate boundary

Question 9

The accounts for 83 percent of Earth's volume.

A) mantle
B) inner core
C) crust
D) outer core

Question 10

The rigid outer layer of Earth that comprises the continental crust, oceanic crust, and the uppermost mantle is called the .

A) hydrosphere
B) lithosphere
C) asthenosphere
D) outer core

Question 11

Earlier than 200 million years ago, the continents were joined into one supercontinent called .

A) Pangaea
B) Panthalassa
C) Oceanus
D) Tethys

Question 12

The youngest seafloor rocks are found .

A) near the edges of continents
B) near the rift valleys of mid-ocean ridges
C) beneath the deep sea trenches
D) evenly distributed over the ocean basins

Question 13

What are the primary elements in Earth's continental crust?

A) oxygen, uranium, and  thorium
B) oxygen, silicon, and  uranium
C) oxygen, silicon, and  aluminum
D) iron, aluminum, and  carbon

Question 14

A "mystery" in our understanding of plate tectonics has been, until recently, the nature of the power source capable of moving the plates and the continents embedded within them. Recent evidence indicates the power source to be .

A) the readjustment of the surface to continual shrinking of the whole Earth
B) convection currents within Earth's mantle moving the plates
C) the action of ocean currents dragging along the seafloor, causing the seafloor and the continents to move
D) the continual vibration from earthquakes and volcanoes slowly moves the continents equator-ward under the influence of centrifugal force

Question 15

About how many kilometers (miles) is it from the center of Earth to the outer edge of the outer core?

A) 12,523 kilometers (7,827 miles)
B) 6,370 kilometers (3,980 miles)
C) 1,264 kilometers (790 miles)
D) 2,880 kilometers (1,800 miles)

Question 16

The mid-ocean ridges are .

A) subduction zones
B) ocean - ocean convergent boundar ies
C) divergent plate boundaries
D) ocean - continent convergent plate boundaries

Question 17

A cross section of Earth reveals a layered structure that has different thicknesses and densities. How do geologists know this?

A) from drilling and digging down into the various layers
B) from observing the characteristics of lava and gas issuing from volcanic vents
C) from observing the transit times through Earth of seismic waves generated by earthquakes
D) from comparisons with drill cores taken by robot spacecraft on Mars and Venus

Question 18

The hot, partially melted, slowly flowing layer of Earth is called the .

A) inner core
B) asthenosphere
C) lithosphere
D) outer core

Question 19

One cubic meter of which of these would weigh the most?

A) ocean water
B) granite rock
C) basaltic rock
D) mantle

Question 20

Roughly how fast do most lithospheric plates move?

A) about 5 kilometers per year
B) about 5 kilometers per thousand years
C) about 5 centimeters per hour
D) about 5 centimeters per year

Question 21

One piece of evidence that suggests the existence of Pangaea is the apparent fit of continents across North and South Atlantic.

Question 22

Subduction zones are areas where new seafloor is created.

Question 23

The Himalayan Mountains were formed as a result of .

A) ocean - continent convergence
B) continent - continent convergence
C) ocean - ocean divergence
D) continent - continent divergence

Question 24

Which statement about hot spots is true?

A) Hot spots arise from relatively stationary plumes of magma in the mantle.
B) Hot spots are always located along plate boundaries.
C) Hot spots are never associated with volcanoes.
D) Hot spots can only exist beneath oceanic crust.

Question 25

A boundary in which crustal plates slide laterally past one another is called a .

A) transform fault
B) convergent zone
C) divergent zone
D) rift valley

Question 26

The Hawai'ian Islands formed as they pass over a hot spot in the middle of the .

A) Mid-Atlantic ridge
B) Nazca Plate
C) Mariana Trench
D) Pacific Plate

Question 27

The oceanic crust is primarily made of basalt.

Question 28

The Hawai ' ian Islands were formed within the last 2 million years above a hot spot that is now inactive.

Question 29

Geologists believe that a new ocean basin is forming .

A) at the East African Rift Valley
B) in the Mediterranean Sea
C) along the divergent boundary between India and Asia
D) along the boundary between the Nazca Plate and the South American Plate

Question 30

Some plateaus, ocean ridges, ancient island arcs, and parts of continental crust are too buoyant to be subducted. These are, instead, squeezed and sheared onto the face of a continent, forming .

A) Wadati-Benioff zones
B) terranes
C) rift valleys
D) sea mounts

Question 31

There are three types of plate convergences: continent-continent, ocean-continent, and ocean-ocean convergent plate boundaries.

Question 32

The asthenosphere is cooler than the lithosphere.

Question 33

Which statement is true with regard to subduction zones?

A) They are also referred to as hot spots.
B) They are sites where lithospheric plates are diverging or pulling apart.
C) They are marked by the presence of mid-ocean ridges.
D) They are zones where old seafloor descends into the crust and mantle.

Question 34

Density is a measure of relative heaviness and is defined as mass per unit volume.

Question 35

Alfred Wegener was a polar explorer who suggested that at one time, Earth's landmasses were joined into a supercontinent called Pangaea.

Question 36

The largest known mantle plume is located beneath .

A) Antarctica
B) Africa
C) Hawai'i
D) Yellowstone National Park

Question 37

The magnetic striping of the seafloor is considered evidence of seafloor spreading and .

A) periodic interruptions in mantle convection
B) subduction occurring in rift valleys
C) changes in Earth's axis of rotation
D) periodic reversals in the polarity of Earth's magnetic field

Question 38

Plate tectonics (continental drift) is driven by convection currents of slow-moving material within Earth's inner core.

Question 39

Transform faults are never found at mid-ocean ridges.

Question 40

New crust is being generated .

A) in the deep ocean trenches
B) at convergent plate boundaries
C) at divergent plate boundaries
D) at the centers of tectonic plates

Question 41

Using the Atlantic Ocean as an example, describe in detail how an ocean basin is formed.

Question 42

What factors determine the behavior of a rock?

A) temperature, pressure, and the rate of at which a deforming force is applied
B) location, depth, and pressure
C) temperature, chemical composition, and location
D) pressure, depth, and chemical composition

Question 43

The  type of plate boundary can be determined by evaluating the depths of earthquakes. What seismic trend would occur at ocean-continent convergent boundaries?

A) The depth of earthquakes would increase as you move from oceanic crust toward continental crust.
B) The depth of earthquakes could decrease as you move from oceanic crust toward continental crust.
C) Earthquake depths would remain constant as you move from oceanic crust to continental crust.
D) Only shallow earthquakes would occur along ocean - continent convergent boundaries.

Question 44

What kind of observational evidence did Alfred Wegener use to propose his theory of continental drift and the idea that the continents were once connected as the single landmass, Pangaea?

Question 45

Loihi is an excellent example of a(n) .

A) subduction zone near the Hawai'ian islands
B) new island forming under a hot spot beneath the Pacific plate
C) exotic terrane accreted onto the westernmost region of North America
D) extinct submerged volcano moving away from the East Pacific Rise

Question 46

What is plate convergence and what types of features are produced from convergence?

Question 47

Besides the shoreline fit of continents, what other evidence did Alfred Wegener use to support his theory of continental drift?

A) The measured speed of the moving continents.
B) Similar seawater compositions on both sides of the Atlantic Ocean.
C) Ice core samples indicating similar CO ₂ measurements at both poles.
D) The alignment of mountain ranges, fossils, and coal between separated continents.

Question 48

Ocean basins have opened and closed over great spans of time during Earth's history.  This process of opening and closing is called a .

A) Wilson cycle
B) d ivergent - convergent cycle
C) c onvection current
D) u plift-subduction cycle

Question 49

Which statement best describes ocean sediments near mid-ocean ridges?

A) The layers of sediment reach 150 to 200 feet in thickness near mid-ocean ridges.
B) Ocean sediments are greater than 200 million years in age at mid-ocean ridges.
C) Ocean sediments are nearly absent near mid-ocean ridges.
D) The layers alternate between fine-grained sediments and lava beds near mid-ocean ridges.

Question 50

Which location is associated with a divergent plate boundary?

A) East Africa
B) California
C) Andes, South America
D) Aleutian Trench

Question 51

Which plate does the westward-moving South American Plate encounter in South America?

A) Cocos plate
B) Juan De Fuca plate
C) Farallon plate
D) Nazca plate

Question 52

If there was once one supercontinent over 200 million years ago, then there was a single ocean called .

A) Pangaea
B) Panthalassa
C) Oceanus
D) Tethys

Question 53

Describe the mechanism that controls the formation of the Hawai'ian Islands. Is this island chain still actively forming?

Question 54

Which layer of Earth is a very hot, dense, and viscous liquid composed mostly of iron and nickel?

A) outer core
B) inner core
C) asthenosphere
D) lower  mantle

Question 55

What would cause continental crust to become thinner in mountainous regions?

A) erosion, isostatic uplift, and further erosion
B) volcanic eruptions
C) subduction of continental crust beneath oceanic crust
D) extension and contraction of asthenosphere

Question 56

How has the history of plate movement been captured in residual magnetic fields?

Question 57

Tiny particles of iron-bearing magnetic minerals, such as , act as a compass needle at mid-ocean ridges when magma erupts and cools recording Earth's magnetic field.

A) quartz
B) muscovite
C) magnetite
D) hornblende

Question 58

If Earth were uniform (homogenous) throughout, seismic waves would .

A) not travel from the site of an earthquake and stop at its origination point
B) bend as it moves from the earthquake site toward the center of Earth and then back to the surface
C) be reflected from the earthquake site after traveling half the distance to the center
D) radiate from the site of an earthquake in straight lines

Question 59

What type of boundary is located in the Northwestern United States and forms the Cascade Ranges?

A) transform boundary
B) divergent boundary
C) ocean - continent convergent boundary
D) continent - continent convergent boundary

Question 60

Why don't tall mountains in the continental crust sink and disappear into the partially melted asthenosphere?

A) The asthenosphere is rigid and doesn't allow the mountain to sink.
B) The continental crust is lighter than the asthenosphere so it can't sink.
C) Mountains do sink into the asthenosphere, but only until they have displaced a volume of asthenosphere equal to their mass.
D) The asthenosphere is constantly building up the mountain from below so it can't sink.

Question 61

The continental crust of the Pacific Northwest and Alaska are much different from the rest of the United States. What process would account for these varied differences?

Question 62

Mid-ocean ridges are almost free of sediment.

Question 63

Major plates move on average about the rate at which fingernails grow.

Question 64

There are two ways in which Earth's layers can be classified: chemical composition and physical properties.  Briefly describe the different layers by their chemical composition and then by their physical properties.

Question 65

Our Earth is approximately 4.6 billion years old. The oldest continental crust was recently found in Australia and contained pieces of zircon that dates back to about 4.4 billion years. The oldest oceanic crust dates back to only 180 to 200 million years old. What would account for the large discrepancy in age between the oldest continental crust and the oldest oceanic crust?

Question 66

From the time accurate charts became available in the late 1700s, observers noticed the remarkable coincidence of the shape of the Atlantic coasts of Africa and South America. What additional evidence strengthened the idea of continental drift with regards to geographic fit?

Question 67

How does the analysis of seismic waves reveal information about the nature of Earth's interior?

Question 68

The lithosphere included the oceanic crust, the continental crust, and the uppermost cool and rigid part of the mantle.

Question 69

Particles of iron-bearing magnetite occur naturally in basaltic magma. As this magma forms new seabed, the magnetic particles cool, "locking" their magnetic orientation to that of Earth's prevailing magnetic field.

Question 70

Alfred Wegener used the differences in mountain age, composition, and structure on both sides of the Atlantic to support his theory of continental drift.