Deck 3: Earth Structure and Plate Tectonics

Question 1

The youngest seafloor rocks are found:

A) nearest the continental slopes.
B) near the rift valleys of the mid-ocean ridges.
C) beneath the deep sea trenches.
D) evenly distributed over the ocean basins.

Answer 1

B

Question 2

What do these things have in common: Paleomagnetism, seafloor spreading, Pangaea, Wadati-Benioff zones, transform faults, fracture zones, seamount chains, Pacific hotspots.

A) They are used to study earthquakes.
B) They are involved with plate tectonics.
C) They are used to investigate the potential for undersea mining and mineral resource exploitation.
D) They are used to predict earthquake activity and warn people of imminent danger.

Answer 2

B

Question 3

About how many kilometers (miles) is it from the Earth's center 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)

Answer 3

B

Question 4

Which of the following lists represents the main components of the Earth's crust?

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

Question 5

Which of these is most abundant on or in the Earth?

A) mantle material
B) granite rock
C) liquid water
D) basalt

Question 6

As early as the 1700s, scientists and explorers notice a remarkable coincidence of shape of the Atlantic coasts of Africa and which continent?

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

Question 7

The Earth's youngest rocks are found:

A) in the deepest part of the flat ocean bottom.
B) at the mid-ocean ridges.
C) at the cores of the continents.
D) in trenches.

Question 8

The outermost solid layer of the Earth that comprises both continental and oceanic crust is called the:

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

Question 9

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

A) Pangaea.
B) Panthalssa.
C) Oceanus.
D) Tethys.

Question 10

Evidence for plate tectonics can be seen in:

A) the distribution of marine microbes.
B) ancient glaciers.
C) the distribution of dissolved compounds in isolated regions of the ocean.
D) modern snail species.

Question 11

New crust is being generated:

A) in the deep trenches.
B) in submarine canyons.
C) in the rift valleys of the mid-ocean ridges.
D) at the centers of large continents.

Question 12

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 the Earth of waves generated by large earthquakes.
D) From comparisons with drill cores taken by robot spacecraft on Mars and Venus.

Question 13

The Hawaiian 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 14

If two oceanic plates collide at a relatively fast speed, and one is much older and cooler (therefore more dense) than the other, what will happen?

A) A deep trench will form.
B) Continental mountains will form.
C) Large earthquakes will occur.
D) A volcano will erupt. .

Question 15

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 the Earth's mantle is moving the plates.
C) the action of ocean currents is dragging along the seafloor, causing the seafloor and the continents to move.
D) the continual vibration from earthquakes and volcanoes slowly moves the continents equatorward under the influence of centrifugal force.

Question 16

Why is the inside of the Earth still hot?

A) Because the outer layers have prevented the escape of heat trapped during the planet's initial formation, and no new heat has been formed.
B) Because the decay of large radioactive elements is creating heat in the Earth's inner layers.
C) Because a nuclear process like that found in stars is at work in Earth's interior.
D) Because huge quantities of oil and natural gas occasionally burn deep within the Earth.

Question 17

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

A) seawater
B) granite rock
C) basaltic rock
D) mantle

Question 18

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

A) subduction down the rift valleys.
B) spreading centers in the trenches.
C) changes in the Earth's axis of rotation.
D) periodic reversals in the polarity of the Earth's magnetic field.

Question 19

A boundary in which crustal plates move past one another is called a:

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

Question 20

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) displacing a volume of water which weighs slightly more than its own weight.
D) displacing a volume of water which weighs slightly less than its own weight.

Question 21

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

Question 22

Subduction zones are areas where new seafloor is created.

Question 23

Japan is located along the Pacific Ring of Fire and experiences many earthquakes. Almost all 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.

Question 24

The Hawaiian Islands were formed within the last 2 million years under a hot spot that is now inactive.

Question 25

Transform faults are never found at mid-ocean ridges.

Question 26

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

Question 27

Geologists believe that a new ocean basin is forming:

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

Question 28

With the use of radiometric dating, one would expect to find the OLDEST rock to be found:

A) in the center of the Earth's core.
B) near the middle of the Pacific plate.
C) in the center of the Mid-Atlantic Ridge.
D) in the center of continents.

Question 29

There are 2 types of plate divergences: divergent oceanic crust and divergent continental crust.

Question 30

Oceanographers 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.

Question 31

One piece of evidence that suggests the existence of Pangaea is continuous mountain ranges spanning Australia and Antarctica.

Question 32

One force that drives plate movement is:

A) convection.
B) winds.
C) ocean currents.
D) conduction.

Question 33

All of the following statements are true concerning subduction zones EXCEPT:

A) they are belts of deep-focus earthquakes.
B) they are sites where lithospheric plates are diverging or pulling apart.
C) they are marked by the presence of deep-sea trenches.
D) they are zones where old seafloor descends into the crust and mantle.

Question 34

The oceanic crust is made of basalt.

Question 35

The Emperor Seamounts were formed:

A) as islands formed over a hot spot.
B) as an island arc that formed along a trench.
C) as islands formed over a spreading center
D) islands formed at a convergent zone.

Question 36

The hot, partially melted, slowly flowing layer of the earth is called the:

A) core.
B) asthenosphere.
C) lithosphere.
D) mantle.

Question 37

The mid-ocean ridges are:

A) subduction zones.
B) transform or lateral plate boundaries.
C) divergent plate boundaries.
D) convergent plate boundaries.

Question 38

The asthenosphere is cooler than the lithosphere.

Question 39

Convection in the asthenosphere, in part, facilitates continental drift.

Question 40

Roughly how fast do most lithospheric plates move?

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

Question 41

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

Question 42

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

Question 43

Describe the Wilson Cycle. How can this cycle be used to explain plate tectonics?

Question 44

Are the Hawaiian Islands moving? If yes, why, how fast, and in what direction?

Question 45

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