Deck 15: Shorelines and Shoreline Processes

Question 1

Describe how a coral atoll forms.

Answer 1

A fringing coral reef forms around an island, usually a volcano. As the oceanic plate moves away from the spreading center or volcanic hotspot, the plate cools, it becomes denser, and subsequently, becomes less buoyant and sinks. The coral continues to grow upward but the island erodes and disappears below the surface resulting in the coral remaining on the surface as an atoll.

Question 2

Briefly explain what the effects of rising sea level are on the barrier islands along the United States coastlines and why coastal communities are concerned.

Answer 2

Rising sea levels cause erosion, shoreward migration of barrier islands, and even their submergence. This is of concern because so many expensive beachfront properties are located on barrier islands and since barrier islands protect the mainland from erosion and flooding, and constitute an important part of the natural coastal wetland habitat.

Question 3

What causes a wave to break when it reaches shore?

Answer 3

As waves enter shallow water, the broad waves of deep water become sharp-crested. This transformation begins at wave base, one-half the wavelength. The wave touches the seafloor, and the orbital motion at the bottom of the wave is disrupted. The wave is pushed upward by the sea bottom and becomes oversteepened. Eventually the crest plunges forward as a breaker.

Question 4

Why must elected officials and city planners of coastal communities understand the geologic processes of shorelines?

Question 5

What options do geologists and engineers have in combating the effects of rising sea level?

Question 6

What is a beach, and what are the component parts of a beach?

Question 7

Describe the way a wave moves and what wave speed measures.

Question 8

What are two ways (one natural and one human-induced) in which the sediment budget of a coastline can become negative?

Question 9

How does the Moon generate tides? Why are there generally two high tides and two low tides a day?

Question 10

What are winter and summer beaches? How can the same beach have two such different seasonal profiles?

Question 11

In most locations ocean water salinity is in dynamic equilibrium, inputs equal outputs. What does this mean and what are the inputs and outputs for dissolved solids in seawater?

Question 12

What are barrier islands, and where do they form? How does the sand migrate on barrier islands?

Question 13

What caused the bulk of the damage by Hurricane Katrina to the city of New Orleans? Why was New Orleans so vulnerable?

Question 14

Describe how waves are generated.

Question 15

How do rip currents form, and what should you do if you are caught in one?

Question 16

What causes tides? Which of these is stronger, and why?

Question 17

What are longshore currents, and how do they form? Why are they important to shoreline processes?

Question 18

Why do waves bend or refract as they approach shorelines?

Question 19

Outline and describe factors that are responsible for global surface circulation patterns. Where are the cold and warm water currents and how do they moderate Earth's temperature?

Question 20

What are spring tides and neap tides, and what causes them?

Question 21

How are sea cliffs eroded?

Question 22

Describe how a coast can become emergent.

Question 23

Methane hydrates could provide a lot of energy for us to use. Outline the reasons that these resources are not yet being used.

Question 24

What are the primary agents of sediment transport and deposition along shorelines?

Question 25

How would a country, such as Bangladesh, be affected by a 2 meter rise in sea level?

Question 26

What is the most important agent for modifying the equilibrium profile of beaches?

Question 27

What path do water particles in a wave ideally follow?

Question 28

What is a wave-cut platform, and how does one develop?

Question 29

What is the cause of rising sea level?

Question 30

What is the nearshore sediment budget?

Question 31

Why do wave sizes in ponds and lakes have less magnitude than those in oceans?

Question 32

In what direction do longshore currents flow?

Question 33

What characteristics along a seacoast indicate that erosion predominates over deposition?

Question 34

How does the budget or volume of sand on a given beach change through the year?

Question 35

Give a possible reason why beach residents might construct a groin on a beach. What is a probable negative effect of such a construction?

Question 36

How do marine terraces form?

Question 37

Briefly explain how sea level could fall in one region while it is generally rising elsewhere.

Question 38

What are the two factors that control the absolute rate of sea level rise in a particular shoreline?

Question 39

Define the photic and aphotic zones in the ocean.

Question 40

How do shoreline processes tend to straighten an initially irregular shoreline?

Question 41

Regularly sized waves with long, rounded crests are known as ____________________.

Question 42

Large-scale surface water circulation systems in the oceans are known as ____________________.

Question 43

High water that occurs with the eye of a storm coupled with storm waves reaching a shoreline is called ____________________.

Question 44

The highest part of a wave is known as its ____________________, and the lowest part is its ____________________. The wave ____________________ is the difference between these two points.

Question 45

A(n) ____________________ is the location where land meets the sea; a(n) ____________________ is that plus the land both seaward and landward of it.

Question 46

The distance from one crest (or trough) to the next in a wave is the ____________________.

Question 47

The presidential proclamation in the United States claims sovereign rights over an area extending 200 nautical miles seaward is _________________________.

Question 48

Tidal ranges are lowest where the sea bottom is ____________________ in slope and the inlet is ____________________ in width, and are highest where the slope is ____________________ in slope and the inlet is ____________________ in width.

Question 49

Spits and baymouth bars are formed due to ____________________ currents.

Question 50

Orbiting molecules of water in a wave touch the sea or lake floor at the depth of the ____________________.

Question 51

If hydraulic action and abrasion undercut headlands, structures known as ____________________ may form. When these join, they form a(n) ____________________, which might later collapse to give rise to a(n) ____________________.

Question 52

The velocity of a wave is calculated as the ____________________ divided by the ____________________.

Question 53

The bending of waves toward shore as they approach from an oblique angle is called wave ____________________.

Question 54

The average salinity of seawater can be expressed as ____________________ grams per kilogram of seawater, ____________________ parts per thousand, and ____________________ percent.

Question 55

A structure built perpendicular to shore to enlarge a beach or prevent erosion is a(n) ____________________.

Question 56

The two important types of nearshore currents are ____________________ currents and ____________________ currents.

Question 57

Energy is transferred from wind to water to generate waves by ____________________.

Question 58

The transfer of water from depth to the surface is known as ____________________. The transfer of water in the opposite direction is known as ____________________.

Question 59

Tides that occur when the Sun and Moon are at right angles to one another and have wave-generating abilities that cancel each other out are ____________________ tides.

Question 60

The rising tide is also known as the ____________________ tide. The falling tide is known as the ____________________ tide.

Question 61

Wave-cut platforms along northern coastlines of North America and the Great Lakes are exposed as the result of:

A) rising sea level.
B) sediment erosion.
C) sediment deposition.
D) isostatic rebound.
E) falling sea level.

Question 62

A beach with a wide berm, a gentle slope, and a smooth offshore profile is a:

A) summer beach.
B) winter beach.
C) high-energy beach.
D) tide-dominated beach.
E) sediment-poor beach.

Question 63

Spring tides are tides:

A) that result from the combined gravitational force of the aligned Moon and Sun.
B) that occur when the Sun and Moon are disposed at right angles to one another.
C) that occur in springtime when floodwaters are high.
D) with a relatively small range.
E) that are high only once per day.

Question 64

Sea level could change relative to a shoreline due to:

A) uplift of coastal regions.
B) subsidence of coastal regions.
C) rising sea level.
D) receding sea level.
E) all of the above

Question 65

The diameter of a water molecule orbit increases with depth until the wave reaches the seafloor.

Question 66

A beach with a small berm, coarser sediment, and offshore sand bars is a:

A) summer beach.
B) winter beach.
C) high-energy beach.
D) tide-dominated beach.
E) sediment-poor beach.

Question 67

Rip currents commonly develop in regions where wave heights are highest.

Question 68

A spit that connects an island to the mainland is a:

A) hook.
B) tombolo.
C) barrier island.
D) beach.
E) baymouth bar.

Question 69

A deposit of unconsolidated sediment that extends landward from low tide to a change in topography or to where permanent vegetation begins is a:

A) spit.
B) tombolo.
C) barrier island.
D) beach.
E) baymouth bar.

Question 70

Water in waves is displaced from the circular orbits when:

A) waves enter progressively shallower water.
B) seas become swells.
C) waves reach great heights.
D) waves reach great lengths.
E) winds reach a critical velocity.

Question 71

Narrow surface currents that flow in the same general direction as the approaching waves are:

A) rip currents.
B) nearshore currents.
C) longshore currents.
D) upwelling currents.
E) refraction currents.

Question 72

In the open ocean salinity ranges from 32 to 37%.

Question 73

Coriolis effect is the deflection of freely moving bodies, such as air or water molecules, due to Earth's rotation.

Question 74

The distance wave-producing winds blow over a continuous body of water is the:

A) wavelength.
B) trough.
C) height.
D) fetch.
E) velocity.

Question 75

Waves are oscillations of the water surface.

Question 76

The tiny shells of marine organisms form marine sediments called:

A) calcite
B) reefite
C) pelagic clay
D) ooze

Question 77

A coast that is straight and has marine terraces is a(n):

A) depositional coast.
B) erosional coast.
C) submergent coast.
D) emergent coast.
E) none of the above

Question 78

Currents that form from the collective movement of wave water refracted off a shoreline are:

A) rip currents.
B) nearshore currents.
C) longshore currents.
D) upwelling currents.
E) refraction currents.

Question 79

Individual sand grains move along a beach:

A) straight in the direction of the longshore current.
B) straight offshore.
C) in circles up and down the beach face but not horizontally down the beach.
D) in a zigzag pattern in the direction of longshore currents.
E) only during storms.

Question 80

Vertical ocean circulation is the result of differences in what between adjacent water masses?

A) Temperature
B) Salinity
C) Coriolis effect
D) temperature and salinity