Chapter 20 Shorelines
Earth: An Introduction to Physical Geology, 9e (Tarbuck/Lutgens)
20.1 Multiple-Choice Questions
1) Fetch refers to ________.
A) a large expanse of open water over which the wind blows and generates waves
B) ocean currents moving parallel to the beach
C) the rotational movements of water particles beneath a passing, surface wave
D) the beachfront area where rapid erosion is taking place
Answer: A
Diff: 1
2) A deep-water wave exists when ________.
A) the wavelength exceeds one-half the water depth
B) the wavelength exceeds one-half the wave height
C) the water depth exceeds one-half the wavelength
D) the wave height exceeds the water depth
Answer: C
Diff: 1
3) Water movement and sand transport parallel to the beach are fundamentally caused by
________.
A) strong, offshore winds creating a pileup of water along the beach front
B) deep-water waves breaking offshore
C) waves impinging obliquely onto a beach
D) a long fetch parallel to the beach
Answer: C
Diff: 1
4) Swash and backwash describe ________.
A) movements of water and sand as waves break along a beach
B) the oscillatory movement of water beneath a passing wave
C) the swirling action and sand movements produced when a shallow water wave
impinges on the bottom
D) the forward and backward water movements as storm waves reflect from a seawall or
groin
Answer: A
Diff: 1
1
5) How does refraction affect the crest and trough orientations of incoming waves along a
beach?
A) as the waves move into shallower water, the angle between the wave crests (troughs)
and the shoreline increases
B) as the waves move into shallower water, the angle between the wave crests (troughs)
and the shoreline decreases
Answer: B
Diff: 1
6) ________ are built more or less parallel to the beach.
A) Jetties
B) Seawalls
C) Groins
D) Breakers
Answer: B
Diff: 1
7) Over the past few thousand years, how, if at all, has sea level been changing?
A) It has fallen about 10 inches per century.
B) It has risen about 10 centimeters per century.
C) It has remained about the same.
D) none of the above
Answer: B
Diff: 1
8) How can crashing, collapsing, storm waves generate explosive forces and stresses on rocky
outcrops and manmade structures?
A) pressurized water and compressed air are driven into cracks and fissures
B) backwash breaks out blocks of rock or concrete and carries them out to deeper water
C) oscillating, refractive waves shake the hard materials into small fragments
D) all of the above
Answer: A
Diff: 1
9) Increasing quantities of ________ will eventually produce global warming.
A) carbon dioxide
B) ozone
C) water vapor
D) volcanic aerosols
Answer: A
Diff: 1
2
10) Erosional retreat of a ________ leads to enlargement and extension of a wave-cut platform in
the inland direction.
A) wave-cut cliff
B) wave-cut barrier beach
C) wave-cut tombolo
D) offshore, wave-cut, breakwater bar
Answer: A
Diff: 1
11) How are spits, hooks, and baymouth bars formed?
A) A headland is eroded and the sand is deposited in an offshore basin.
B) Wave erosion cuts away both sides of a long sand bar, leaving a sand ridge aligned
parallel to the shore.
C) Sand is deposited from longshore currents.
D) Sand eroded from a wave-cut diff is deposited around sea stacks and arches.
Answer: C
Diff: 1
12) Which one of the following coastlines would typically have wave-cut cliffs, sea stacks, sea
arches, and wave-cut platforms?
A) one where bedrock is vigorously eroded as sea level rises
B) one where a bedrock, wave-cut cliff is rapidly retreating inland as sea level falls
C) one where unconsolidated sediments are being eroded as sea level falls
D) one where unconsolidated sediments are being rapidly eroded as sea level rises
Answer: A
Diff: 1
13) Emergent coastlines of Scandinavia (Norway and Sweden) and the Hudson Bay region of
Canada result from which one of the following combinations?
A) the rate of glacial rebound exceeds the rate of sea level rise
B) the tectonic subsidence rate exceeds the rate of sea level rise
C) the rate of glacial rebound is less than the rate of sea level rise
D) the rate of tectonic uplift exceeds the rate of sea level fall
Answer: A
Diff: 1
14) Large estuaries are more common on a ________ coastline.
A) submergent
B) retreating
C) stable
D) emergent
Answer: A
Diff: 1
3
15) A ________ tide is an incoming or rising tide.
A) drift
B) flood
C) ebb
D) rip
Answer: B
Diff: 1
16) ________ are the maximum-amplitude tides produced when the Sun, Earth, and Moon are
aligned.
A) Rip tides
B) Spring tides
C) Surf tides
D) Neap tides
Answer: B
Diff: 1
17) Which of the following is true regarding the gravitational forces affecting Earth?
A) The lunar force is about twice that of the Sun.
B) The solar and lunar gravitational forces are about the same magnitude.
C) The solar force is about twice that of the Moon.
D) The gravitational forces of each vary depending upon seasons on Earth.
Answer: A
Diff: 1
18) Which of the following statements concerning the Mississippi delta lands is not true?
A) Coastal erosion and loss of delta lands will continue as sea level continues to rise.
B) Artificial levees help spread river-borne sediment uniformly over the delta swamps
and wetlands.
C) The sediment supply has dropped since large reservoirs were constructed on the
Missouri and Arkansas Rivers.
D) The thick sediment pile is slowly compacting and the delta is slowly subsiding.
Answer: B
Diff: 1
19) ________ refers to the broad dome of water moving with the eye and frontal portion of a
hurricane.
A) Cyclonic mound
B) Storm surge
C) Eyewall ridge
D) Sea dome
Answer: B
Diff: 1
4
Match the policy options with expected costs and long-term effectiveness, assuming that sea level will
continue to slowly rise in the future.
A. promote coastal development; build massive, hardened structures to stop all but the
most powerful storm waves
B. prohibits coastal development; build nothing, declare victory over the sea and retreat
from the coastline
C. allow coastal development; make a long-term commitment to beach nourishment
20) ________ low initial costs and modest maintenance costs; high potential for storm damages
and low to moderate potential for negative environmental effects
Answer: C
Diff: 2
21) ________ high initial costs and eventually high maintenance costs; high potential for storm
damage and negative environmental consequences
Answer: A
Diff: 2
22) ________ low initial costs and low maintenance costs; low potential for storm damages and
for negative environmental consequences
Answer: B
Diff: 2
23) ________ is not a dynamic characteristic of a wave of oscillation.
A) Fetch
B) Velocity or speed
C) Wavelength
D) Period
Answer: A
Diff: 1
24) ________ are currents that move sand and water parallel to the beach.
A) Reflected
B) Longshore
C) Translational
D) Ebb tide
Answer: B
Diff: 1
25) When does a deep-water wave change to a shallow water wave?
A) only when the wave period is greater than one-half the water depth
B) only when the wavelength is about twice the water depth
C) only when the wavelength is about one-half the water depth
D) only when the wave period is greater than twice the water depth
Answer: B
Diff: 1
5
26) Incoming waves slow down and rotate towards an orientation of being parallel to the
shoreline. This process is known as ________.
A) reflection
B) relaxing
C) refluxing
D) refraction
Answer: D
Diff: 1
27) Which one of the following would prove that a coastline was emergent?
A) elevated, wave-cut terraces
B) many small bedrock islands
C) extensive barrier islands
D) numerous large estuaries
Answer: A
Diff: 1
28) Which one of the following is an artificial coastal feature?
A) breakwater
B) sand spit
C) sea arch
D) barrier island
Answer: A
Diff: 1
29) ________ refers to the movements of sand and water on a beach due to a breaking wave.
A) Swash and slosh
B) Backwash and swash
C) Slash and slosh
D) Wash and backslosh
Answer: B
Diff: 1
30) A ________ is an isolated remnant of bedrock standing above a wave-cut platform.
A) sea stack
B) sea span
C) sea rampart
D) sea spit
Answer: A
Diff: 1
31) A ________ extends partway across the mouth of a bay or estuary.
A) barrier island
B) spit
C) jetty
D) sand arch
Answer: B
Diff: 1
6
32) A baymouth bar is ________.
A) a sand deposit on the seaward side of a tidal inlet to a large estuary
B) a sand bar extending across the former inlet to a bay or estuary
C) a sand barrier extending partway across the entrance to a bay or estuary
D) a sand deposit on the estuary side of an inlet through a barrier island
Answer: B
Diff: 1
33) A ________ migrates inland as a wave-cut platform is extended.
A) wave-cut barrier dune
B) wave-cut barrier stack
C) wave-cut arch
D) wave-cut cliff
Answer: D
Diff: 1
34) Which one of the following would not be a likely effect of a breakwater?
A) increased, longshore current velocities between the breakwater and the beach
B) dissipation of storm wave energy on the seaward side of the breakwater
C) increased sand deposition between the beach and the breakwater
D) increased erosion of the beach on one side of the breakwater
Answer: A
Diff: 1
35) A natural sand bar or low, sand ridge that connects one island to another island or to the
mainland is called a ________.
A) sand groin
B) spit
C) jetty barrier
D) tombolo
Answer: D
Diff: 1
36) Which one of the following is not directly related to wave refraction?
A) Speeds decrease as waves enter shallow water.
B) Ebb tidal currents carry large quantities of sand from estuaries to the seacoast side of a
barrier island system.
C) Deposition is concentrated in bays and protected waters.
D) Erosional energy is focused on headland areas along the beach.
Answer: B
Diff: 1
37) ________ not the direct result of longshore current action.
A) Building and extension of spits are
B) Closing off of small estuaries by baymouth bars is
C) Transport of sand along the beach is
D) Cracking and abrasion of rock at the base of a wave-cut cliff are
Answer: D
Diff: 1
7
38) A ________ tide is a tidal current flowing through an inlet into a bay or estuary.
A) forward
B) spring
C) flood
D) ebb
Answer: C
Diff: 1
39) ________ are coastal structures designed to keep tidal inlets from shifting location or filling
with sand.
A) Breakwaters
B) Seawalls
C) Jetties
D) Groins
Answer: C
Diff: 1
40) Which one of the following statements concerning sea level is correct?
A) It has dropped since 900 A.D., but will probably rise for the next few hundred years.
B) It dropped during the past few centuries and that trend will continue.
C) It rose over past centuries but will probably drop in the next hundred years.
D) It rose for the past few centuries and will continue to rise.
Answer: D
Diff: 1
Match the coastline type with the appropriate description or location.
A. emergent
B. submergent
41) ________ Chesapeake and Delaware Bays and the North Carolina Sounds
Answer: B
Diff: 1
42) ________ large areas of coastal swamplands, large estuaries, and barrier islands
Answer: B
Diff: 1
43) ________ wave-cut (eroded) cliff, sea stacks, and elevated wave-cut terraces
Answer: A
Diff: 1
8
44) Which of the following correctly describes a fiord (fjord)?
A) deep stream-cut canyon flooded as the coastal lands subsided during the last one
million years
B) deep, glacier-cut valley flooded as the coastal lands subsided during the last one
million years
C) deep, glacier-cut valley flooded by rising sea level over the last 10,000 years
D) deep stream-cut canyon flooded by rising sea level over the last 10,000 years
Answer: C
Diff: 1
Match the tide with the appropriate description.
A. neap tides
B. spring tides
45) ________ Sun, Moon, and Earth form a right triangle in space
Answer: A
Diff: 1
46) ________ lowest high tides and highest low tides of the month
Answer: A
Diff: 1
47) ________ highest high tides and lowest low tides of the month
Answer: B
Diff: 1
48) ________ Sun, Moon, and Earth lie on a straight line in space
Answer: B
Diff: 1
20.2 Word Analysis Questions
Examine the words and/or phrases for each question below and determine the relationship among the
majority of words/phrases. Choose the option which does not fit the pattern.
1) A) berm
B) shoreline
C) beach face
D) beach
Answer: shoreline
Diff: 1
2) A) wave height
B) wave period
Answer: wave refraction
C) wave refraction
D) fetch
Diff: 2
3) A) wave-cut cliff
B) wave-cut platform C) sea arch
Answer: wave-cut platform
D) spit
Diff: 1
4) A) sea stack
Answer: sea stack
B) bar
C) tombolo
Diff: 1
9
D) barrier island
5) A) jetties
Answer: jetties
B) groin
C) seawall
D) beach nourishment
Diff: 1
20.3 True/False Questions
1) The wave period is the horizontal distance between neighboring crests or troughs of a wave.
Answer: FALSE
Diff: 1
2) Tidal flats are mostly submerged during ebb tides.
Answer: FALSE
Diff: 1
3) As waves move into the beach area, they change to waves of translation.
Answer: TRUE
Diff: 1
4) Sea level has been slowly rising since the last Pleistocene ice sheets melted away.
Answer: TRUE
Diff: 1
5) A baymouth bar is a manmade feature designed to stop incoming storm waves before they
impact on the beach.
Answer: FALSE
Diff: 1
6) The effect of the Sun on tides is about one-half that of the Moon.
Answer: TRUE
Diff: 1
7) Because the land is rising faster than sea level, storm damage and erosion along emergent
coastlines are relatively unimportant.
Answer: FALSE
Diff: 1
8) Massive seawalls and groins, financed by the average taxpayer, are very cost-effective
methods for protecting expensive, privately owned, beach front properties.
Answer: FALSE
Diff: 1
9) Deep water waves in the open sea are waves of oscillation.
Answer: TRUE
Diff: 1
10) Elevated, wave-cut platforms are good evidence for an emergent coastline.
Answer: TRUE
Diff: 1
10
11) Barrier islands are quite rare along the Gulf of Mexico coastline.
Answer: FALSE
Diff: 1
12) The rocky Maine coastline is emergent because the land is rising faster than sea level.
Answer: FALSE
Diff: 1
13) Groins are constructed perpendicular to the beach; they are designed to trap sand that might
otherwise keep moving along the beach.
Answer: TRUE
Diff: 1
14) Barrier islands are more common along the Pacific coast of the United States than along the
Atlantic coast.
Answer: FALSE
Diff: 1
15) Over the past few centuries, sea level has been gradually falling.
Answer: FALSE
Diff: 1
16) Spring tides refer to the largest, daily, astronomical tidal range during any month.
Answer: TRUE
Diff: 1
17) Neap tides are produced when the Earth, Sun, and Moon are positioned to form a right
triangle in space.
Answer: TRUE
Diff: 1
18) Water flows into bays, sounds, and estuaries on a flood tide.
Answer: TRUE
Diff: 1
19) Carbon dioxide is the main atmospheric gas associated with the greenhouse effect.
Answer: TRUE
Diff: 1
20) Longshore sand transport and longshore currents depend on waves impinging parallel to a
shoreline.
Answer: FALSE
Diff: 1
21) On submergent coasts with large estuaries and coastal swamps, rivers and streams carry
large quantities of sand directly to the beaches and barrier islands.
Answer: FALSE
Diff: 1
11
22) Fjords are broad, shallow, coastal stream valleys that emerged from the sea as the coastal
bedrock rebounded after the ice melted away.
Answer: FALSE
Diff: 1
23) Delta lands will decrease in area if upstream dams trap sediment, preventing it from
reaching the delta and channelized distributaries which carry sediments directly to deeper
offshore waters.
Answer: TRUE
Diff: 1
20.4 Short Answer Questions
1) As a deep-water wave enters shallow water, the wave slows down and rotates toward being
parallel with the shoreline. This process is known as ________.
Answer: refraction
Diff: 1
2) ________ currents refer to water moving parallel to a shoreline.
Answer: Longshore
Diff: 1
3) ________ are long, narrow, offshore, sand ridges between an estuary and the open ocean are
common along the Atlantic and Gulf of Mexico coasts.
Answer: Barrier islands
Diff: 1
4) A ________ is a low, sand ridge connecting an offshore island with the mainland or with
another island nearer to the mainland.
Answer: tombolo
Diff: 1
5) A ________ is a structure, built parallel to the shoreline to dissipate much of the energy from
incoming waves.
Answer: breakwater
Diff: 1
6) A ________ is a manmade structure, extending at right angles to the beach, built to trap sand
moving parallel to the beach.
Answer: groin
Diff: 1
7) What two terms denote the complex water and sand movements associated with a wave
breaking on a beach?
Answer: swash, backwash
Diff: 1
12
8) What term denotes a sand bar built across the former mouth of an estuary, separating it from
the open sea?
Answer: baymouth bar
Diff: 1
9) Falling tides and tidal currents flowing from an estuary to the open sea are known as
________.
Answer: ebb tides
Diff: 1
10) A ________ is a high rocky pinnacle that rises from a wave-cut platform.
Answer: sea stack
Diff: 1
20.5 Critical Thinking Questions
Use complete sentences, correct spelling, and the information presented in Chapter 20 to answer the
questions below.
1) Shorelines are temporary geologic and topographic features. Explain this statement.
Diff: 2
2) Briefly discuss the movement of sand on a beach environment. Include those factors, both
natural and human-induced, that affect sand movement.
Diff: 3
3) A variety of techniques and efforts are used to stabilize shorelines throughout the world.
Are all of these efforts only temporary measures or are any of them permanent? Also, does
urbanization and development of coastal areas always contribute to shoreline erosion?
Explain.
Diff: 3
20.6 Visualization Questions
1) Label the basic parts of a wave on the diagram below.
Answer: See figure 20.3 in chapter 20 of Earth, 9e
Diff: 1
13
2) What type of current is illustrated in the diagram below?
Answer: See figure 20.10 in chapter 20 of Earth, 9e
Diff: 1
3) Match the features on the illustration below with the correct answer for each one.
A) tombolo
B) wave-cut cliff
C) spit
Answer: a) D b) B c) A d) C
Diff: 2
14
D) baymouth bar
4) Carefully examine the illustration below.
What name is given to walls like the wall above that is labeled A? a) ________
What name is given to walls like the wall above that is labeled B? b) ________
What name is given to walls like the wall above that is labeled C? c) ________
In the future, what will eventually happen to the beach at the following locations?
Location G d) ________ Location F e) ________
Location E f) ________ Location D g) ________
Answer: a) groins b) breakwaters c) jetties
d) It will widen as more sand accumulates
e) It will widen as more sand accumulates
f) It will narrow as sand is removed
g) It will widen as more sand accumulates
Diff: 2
5) Label the tidal flat, tidal delta, and barrier island on the diagram below.
Answer: See figure 20.30 in chapter 20 of Earth, 9e
Diff: 1
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