Deck 2: Earth Structure and Plate Tectonics

Question 1

Volcanic activity associated with subduction zones is more gentle and less explosive than volcanic activity associated with hot spots and midocean ridges.

Answer 1

False

Question 2

P waves travel more quickly than S waves.

Answer 2

True

Question 3

Deep Earthquakes (below 100km or 60mi) are usually associated with oceanic ridges.

Answer 3

False

Question 4

The midocean ridges and rises are spreading centers where new oceanic crust is created.

Question 5

The continental landmasses are less dense than the mantle and are buoyed up by depressing the underlying mantle.

Question 6

Shear waves do not pass through a solid-liquid boundary between Earth's layers. Compressional waves can pass this type of boundary.

Question 7

The thickness of deep-sea sediments increases with distance from a spreading center.

Question 8

The refraction and shadow patterns of seismic P-waves and S-waves indicate the dimensions and properties of Earth's layers.

Question 9

The largest lithospheric plate is the Pacific plate.

Question 10

The North Atlantic Ocean was the first modern ocean to open during the breakup of Pangaea.

Question 11

The edge of an active continental margin bordered by a deep-sea trench is wide and shallow with deep deposits of land-derived sediments.

Question 12

Earth's inner core is liquid whereas its outer core is solid.

Question 13

Isostatic columns of crustal material produce equal pressures deep within the mantle.

Question 14

The deep mantle below the asthenosphere is called the mesosphere.

Question 15

P waves travel only along the Surface of the Earth.

Question 16

The age of the seamounts from Hawaii to Midway Island increases in age from east to west.

Question 17

The San Andreas fault is an example of a transform fault.

Question 18

Epicenters are points on Earth's surface directly above a hot spot.

Question 19

Oceanic-type crust is more dense than continental-type crust.

Question 20

The steeper profile of the Mid-Atlantic Ridge compared to the East Pacific Rise indicates that the Mid-Atlantic Ridge is the faster spreading center.

Question 21

Based on the current directions of plate motion, China and the West Coast of the U.S. are getting closer.

Question 22

The deepest earthquakes occur in subduction zones at oceanic-oceanic plate convergent boundaries.

Question 23

Deposits of sediments are usually thicker along passive continental margins.

Question 24

S waves are able to travel through both solid and liquid.

Question 25

The deepest portion of the lithosphere is formed from

A) oceanic basalt.
B) terrestrial granite.
C) a combination of basalt and granite.
D) mantle material.
E) the Moho.

Question 26

The mechanism causing lithospheric plates to move is thought to be

A) convection in the mantle.
B) "slab pull" caused by subducting lithosphere.
C) tidal forces.
D) Earth's rotation.
E) a combination of convection in the mantle and "slab pull" caused by subducting lithosphere.

Question 27

Which of the following help us believe that Earth's mass is distributed spherically and uniformly around Earth's center?

A) Lack of roughness of Earth's surface
B) Earth's spherical shape
C) Lack of rotational wobble
D) Earth's spherical shape and lack of rotational wobble.
E) Lack of roughness of Earth's surface, Earth's spherical shape, and lack of rotational wobble are correct

Question 28

California is an example of a passive continental margin.

Question 29

Volcanic activity is common at transform plate boundaries.

Question 30

Which of Earth's layers contains the greatest volume of material?

A) Inner core
B) Outer core
C) Mantle
D) Lithosphere
E) Outer crust

Question 31

Spreading at mid ocean ridges tends to occur in increments rather than continuously.

Question 32

Continental crust is generally thicker and less dense than oceanic crust.

Question 33

The Moho is located between the

A) lithosphere and the asthenosphere.
B) crust and the mantle.
C) mantle and the outer core.
D) inner and outer cores.
E) continental margin and the abyssal plain.

Question 34

The taller a mountain is, the deeper its root will extend into the asthenosphere.

Question 35

Sediment thickness on the oceanic crust tends to be greatest in the center of ocean basins

Question 36

The thickness of oceanic crust increases with age.

Question 37

Hess's 1960s theory of mantle convection and seafloor spreading was essentially correct.

Question 38

The oldest oceanic crust is generally in the center of the ocean basin near the mid-ocean ridge or rise system.

Question 39

Higher seafloor heat flow values are found

A) along coastlines.
B) in the middle of ocean basins.
C) near ocean ridge systems.
D) associated with abyssal hills.
E) along the edges of trenches.

Question 40

The density of Earth materials _______ as the core is approached.

A) remains the same
B) decreases
C) increases
D) increases then decreases
E) decreases then increases

Question 41

A program of deep-sea drilling for cores from the ocean's bottom is carried out by the

A) Kon-Tiki.
B) Fram.
C) JOIDES Resolution.
D) Calypso.
E) Beagle.

Question 42

The present oceans have been created during the last

A) 2250 million years.
B) 225 million years.
C) 20 million years.
D) 2 million years.
E) 2 billion years.

Question 43

The trailing margin of a continental landmass ______ than its leading margin.

A) is wider
B) shows less tectonic activity
C) is more stable
D) All of these are correct.
E) is wider and is more stable

Question 44

During the next magnetic reversal, the magnetic force field surrounding Earth will shift by about

A) 45°.
B) 90°.
C) 180°.
D) 270°.
E) 360°.

Question 45

Which of the following are found along subduction zones?

A) Oceanic trenches
B) Active earthquake zones
C) Island arc systems
D) All of these are correct.
E) None of these are correct.

Question 46

Thinning of Earth's crust and the resulting faulting is called

A) convection.
B) subduction.
C) folding.
D) rifting.
E) trailing.

Question 47

The motion between the two sides of a transform fault is greatest

A) outside the adjacent ridge axes.
B) north of the adjacent ridge axes.
C) between the adjacent ridge axes.
D) south of the adjacent ridge axes.
E) east or west of the adjacent ridge axes.

Question 48

Which of the following occurred during the Paleozoic era?

A) Landmasses were strung along Earth's equator.
B) Landmasses drifted across the South Pole.
C) Landmasses came together to form Pangaea.
D) All of these are correct.
E) None of these are correct.

Question 49

Seafloor spreading can be detected by

A) changes in water temperature.
B) changes in water chemistry.
C) acoustic monitoring.
D) submersible observation of the seafloor.
E) All of these are correct.

Question 50

The crust and the mantle are divided into the following layers in order of increasing depth:

A) mesosphere, lithosphere, asthenosphere
B) asthenosphere, lithosphere, mesosphere
C) lithosphere, mesosphere, asthenosphere
D) lithosphere, asthenosphere, mesosphere
E) asthenosphere, mesosphere, lithosphere

Question 51

A fixed volcanic hot spot on Earth tends to produce a _______ on a moving plate.

A) series of volcanic peaks
B) high landmass with a fixed location
C) transform fault system
D) submarine canyon and associated abyssal hills
E) trench

Question 52

Plates move horizontally past each other along

A) transform faults.
B) convergent plate boundaries.
C) divergent plate boundaries.
D) the rift valley.
E) hot spots.

Question 53

Seafloor spreading is continuing at a rate of approximately

A) 1 to 10cm/year.
B) 1 to 10m/year.
C) 1 to 10km/year.
D) 1 to 100cm/year.
E) 1 to 100m/year.

Question 54

The deep-ocean trenches are usually associated with

A) volcanism.
B) island arc systems.
C) earthquakes.
D) All of these are correct.
E) None of these are correct.

Question 55

Which of the Earth's layers has the greatest density?

A) Core
B) Mantle
C) Crust
D) Lithosphere
E) Asthenosphere

Question 56

Magnetic stripes on the seafloor are created at

A) subduction zones.
B) spreading centers.
C) abyssal plains.
D) subduction zones and spreading centers.
E) subduction zones, spreading centers, and abyssal plains.

Question 57

The oceans' oldest sediments are found

A) adjacent to a rift valley.
B) on top of the basalt layer, far from spreading centers.
C) adjacent to a transform fault.
D) at the surface of sediment layers, far from spreading centers.
E) in hot spots.

Question 58

Which method is being used to investigate the structure of the mantle?

A) Isostasy
B) Measurement of seafloor heat flow
C) Seismic tomography
D) Subduction
E) Radiometric dating

Question 59

The Pacific plate is carrying Baja California and the coastal cities of Southern California ______ the continent of North America.

A) away from (west)
B) toward (east)
C) southward along
D) northward along
E) None of these are correct; there is no motion in this region.

Question 60

The east coast of the United States is an example of a(n) __________ continental margin.

A) passive
B) active
C) trailing
D) leading
E) passive and trailing

Question 61

Which statement is true about continental crust?

A) It is composed of granitic-type rock and has a higher density than oceanic crust.
B) It is composed of basaltic-type rock and has a higher density than oceanic crust.
C) It is composed of granitic-type rock and has a lower density than oceanic crust.
D) It is composed of basaltic-type rock and has a lower density than oceanic crust.
E) It is composed of granitic-type rock and has the same density as oceanic crust.

Question 62

Which layer of the Earth contains the greatest mass?

A) Core
B) Mantle
C) Crust
D) Lithosphere
E) Asthenosphere

Question 63

Throughout time, continents break apart and collide and ocean basins open and close.This cyclical process is known as the

A) Wilson cycle.
B) Wegener cycle.
C) lithospheric cycle.
D) Benioff cycle.
E) Richter cycle.

Question 64

Over 170 reversals of Earth's magnetic field have been recorded in the past 80 million years.

Question 65

Earthquakes occur at all of the following except

A) convergent boundaries between two oceanic plates.
B) continental rift valleys.
C) convergent boundaries between two continental plates.
D) mid ocean ridges.
E) Earthquakes occur at all of the above settings.

Question 66

Seismic surface waves travel at about the same speed as ocean waves.

Question 67

The density of the inner core reaches a maximum of about ____ grams/cm³.

A) 150
B) 70
C) 52
D) 31
E) 16

Question 68

Volcanic activity occurs at all of the following except

A) convergent boundaries between two oceanic plates.
B) continental rift valleys.
C) convergent boundaries between two continental plates.
D) mid ocean ridges.
E) convergent boundary between a continental and oceanic plate.

Question 69

Which layer is believed to behave most like a liquid?

A) Outer Core
B) Mantle
C) Crust
D) Lithosphere
E) Inner Core

Question 70

List the following plates in order of largest to smallest:

A) North American, Pacific, Australian, Caribbean, Indian
B) Pacific, Indian, North American, Australian, Caribbean
C) Indian, Pacific, North American, Caribbean, Australian
D) Pacific, North American, Australian, Indian, Caribbean
E) Pacific, Australian, North American, Indian, Caribbean

Question 71

Before Pangaea, there was an earlier supercontinent we call

A) Panthalassa.
B) Gorda.
C) Rodinia.
D) Lefse.
E) Neogenia.

Question 72

When talking about plate tectonics, which of the Earth's layers comprises the plates?

A) Crust
B) Mantle
C) Core
D) Lithosphere
E) Asthenosphere

Question 73

What is the approximate length of the mid ocean ridge system that extends around the globe through all of the major ocean basins?

A) 6,500,000km
B) 650,000km
C) 65,000km
D) 6,500km
E) 650km