Deck 3: Earth Structure and 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

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 2

C

Question 3

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

Answer 3

A

Question 4

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 5

With the development of radiometric dating, scientists discovered that the oldest rocks were typically ____.

A)in the center of the Atlantic Ocean
B)along subduction zones
C)near spreading centers
D)in the center of continents

Question 6

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)A nuclear process 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 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)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 8

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 9

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

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

Question 10

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 waves generated by earthquakes
D)From comparisons with drill cores taken by robot spacecraft on Mars and Venus

Question 11

The ____ accounts for 83% of Earth's volume.

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

Question 12

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

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

Question 13

The rigid outer layer of Earth that comprises both continental and oceanic crust is called the ____.

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

Question 14

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

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

Question 15

If two oceanic plates collide and one is older and cooler (therefore more dense)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 16

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 17

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

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

Question 18

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 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 equator-ward under the influence of centrifugal force

Question 19

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 20

The mid-ocean ridges are ____.

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

Question 21

Convection within the inner core facilitates continental drift.

Question 22

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 23

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 24

Which statement with regard to hot spots is true?

A)Hot spots are relatively stationary features.
B)Hot spots are always located along plate boundaries.
C)The Aleutian Islands in Alaska formed due to a hot spot.
D)Hot spots can only exist beneath oceanic crust.

Question 25

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

Question 26

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 27

Subduction zones are areas where new seafloor is created.

Question 28

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 29

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 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

The oceanic crust is primarily made of basalt.

Question 32

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

Question 33

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

Question 34

The Himalayan Mountains were formed as a result of ____.

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

Question 35

One piece of evidence that suggests the existence of Pangaea is the discovery of Mesosaurus fossils in Argentina and Africa, but nowhere else.

Question 36

Transform faults are never found at mid-ocean ridges.

Question 37

The largest known mantle plume is located beneath ____.

A)Antarctica
B)Africa
C)Hawaii
D)Yellowstone National Park

Question 38

The asthenosphere is cooler than the lithosphere.

Question 39

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

Question 40

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 41

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

Question 42

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

Question 43

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

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

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