Ch. 10 The restless ocean Exam 4

________ are huge circular-moving current systems that dominate the surface of the ocean within an ocean basin.

Gyres

An increase in seawater density can be caused by ________.

either a decrease in temperature or an increase in salinity

Waves begin to "feel bottom" when the depth of water is ________.

equal to one-half the wavelength

When does the spring tide occur?

when the Sun, Moon, and Earth are aligned in a straight line

What happens to a floating object as a wave passes it?

The object will move in a circular path and return to nearly its same original place.

trap

The pier-like structures _____ sand that is moving parallel to the shore.

perpendicular

The pier-like structures are installed ______ to the shore.

maintain or widen

The purpose of the pier-like structures is to _______ the beach and prevent erosion.

How do a wave's speed, wavelength, and height change as the wave moves into shallow water and breaks?

The speed and wavelength of the wave decreases, and the wave's height increases. Submit

What are the differences between neap tides and spring tides? PLEASE SELECT ALL THAT APPLY.

The tidal range of a spring tide is larger than the tidal range of a neap tide. When a spring tide occurs, the moon is new or full. When a neap tide occurs. The moon is at first quarter or new quarter. During a spring tide, the moon, Earth and sun are aligned along a single line. During a neap tide, the moon and sun act on the Earth in right angles.

Why do ocean waves bend around headlands?

The waves are moving more slowly just in front of the headland, causing the waves to bend. Submit

sea stack

an isolated mass of rock standing just offshore, produced by wave erosion of a headland

Gyres are circular, rotating ocean currents that __________.

are predominantly composed of warm and cold ocean currents

The energy that drives surface ocean currents such as the Gulf Stream comes from ________.

prevailing wind patterns

When waves reach shallow water they tend to be ________, which makes them become parallel to the shore.

refracted

Which of the following methods do coastal scientists consider the best permanent option to counteract beach erosion?

relocation of at-risk structures

A ________ is an isolated remnant of bedrock standing above a wave-cut platform.

sea stack

Which type of hard stabilization increases beach erosion? Choose all that apply.

seawall, groin, and breakwater

Which of the following depositional features is produced by longshore transport?

spit

Along which of America's coastal areas are barrier islands common?

the Atlantic and Gulf coastal plains

What is refraction?

the bending of waves due to a change in wave velocity

What is the wavelength?

the distance between consecutive wave crests or troughs

What is the wave height?

the distance between the highest and lowest part of the wave

Fetch is ________.

the distance over which the wind blows over open water

What is the crest of a wave?

the highest part of the wave

What is the wave base?

the lower limit of wave-induced motion in the water

What is the trough of a wave?

the lowest part of the wave

What are the factors that determine the height, length, and period of a wave? PLEASE SELECT ALL THAT APPLY.

the speed of the wind the length of time that the wind has blown the distance that the wind has traveled across open water

What is the wave period?

the time it takes for one wavelength of a wave to pass a particular point Submit

Erosional retreat of a(n) ________ leads to enlargement and extension of a wave-cut platform in the inland direction.

wave-cut cliff

Why do waves approaching the shoreline often bend?

Waves approaching the shoreline often bend because the part of the wave nearest the shore reaches shallow water and slows first, whereas the end that is still in deep water continues forward at its full speed.

How are wave period and wavelength related?

Waves with shorter periods have shorter wavelengths.

Daily changes in the elevation of the ocean surface are called ________.

tides

groin field

The photo of the New Jersey shore is an example of a

What is a beach?

A beach is an accumulation of mobile sediment found along the landward margin of an ocean or a lake.

A friend is considering purchasing a vacation home on a barrier island. Given what you've learned about the impact of waves on coastal landforms, what information and advice could you offer your friend?

Barrier islands tend to experience significant erosion and deposition of sand. Mitigating these effects is extremely difficult and costly. Your friend would be wise to reconsider. A home on a barrier island is likely to take the full brunt of storm waves, making it a risky proposition. Your friend should think twice before purchasing.

erode

Beaches downcurrent from a groin tend to _______ because of beach drift.

Which of the following best describes the relationship between ocean currents and deserts?

Cold air associated with cold ocean currents fails to generate rain in desert regions.

Describe the process of coastal upwelling. Why is an abundance of marine life associated with these areas?

During coastal upwelling, cold water from deeper layers rises and replaces the warmer surface water along the coast of a continent. This process also brings to the surface nutrients such as nitrates and phosphates, which promotes the growth of plankton.

Spit

an elongated ridge of sand that projects from the land into the mouth of an adjacent bay

Which of the below options are correct descriptions of hard stabilization of beaches? PLEASE SELECT ALL THAT APPLY.

Groins, which are built to maintain or widen beaches, are barriers built at a right angle to the beach. Groins unfortunately cause longshore currents to erode sand from the beach on their downcurrent sides. Seawalls are built to reflect the forces of unspent waves on the seaward side. Unfortunately, seawalls cause erosion of the beach on the seaward side.

Which of the following is a true statement regarding currents in a geographic context?

Most poleward-moving currents are warm.

What are alternatives to hard stabilization? PLEASE SELECT ALL THAT APPLY.

Nourishing the beach with sand is an attempt to replenish an eroded beach, but it is a very costly, repetitive procedure that may affect the local ecosystem. Changing the use of beaches so that homes and other structures are no longer built in hazardous areas is an alternative to hard stabilization. However, not everyone is on board with this idea. Submit

What is the effect of wave refraction along an irregular coastline?

Sand will be eroded from the headlands and deposited in the bays, straightening out the shoreline over time.

What happens when storm waves strike an undeveloped barrier island?

The barrier island absorbs the energy of the waves primarily by yielding through the movement of sand. As a result, the barrier island survives the storm waves.

How might building a dam on a river that flows to the sea affect a coastal beach?

The beach becomes narrower and the cliffs behind it are subjected to a higher rate of erosion.

What is the relationship between wave base and wavelength?

The depth of the wave base is one-half the wavelength of the waves.

Why does wave height increase as waves enter shallow water?

The energy of the wave must be contained within a smaller water column in shallow water.

_____ ocean currents create __________ in coastal regions.

Warm, higher temperatures

How does water move as waves pass?

Water moves in a circle in the same direction as wave movement.

How does wave amplitude change with depth in water?

Wave amplitude decreases as depth increases.

Which of the following statements about wave period is most accurate?

Wave period is the inverse of wave frequency.

How does wave refraction at headlands affect deposition and erosion?

Wave refraction at the headland increases erosion at the headland and causes deposition in adjacent bays.

Wave-cut platform

a bench or shelf in the bedrock at sea level, cut by erosion

Sea arch

a feature that forms by wave erosion when caves on opposite sides of a headland unite

Barrier island

a low, elongated ridge of sand that parallels the coast

Tombolo

a ridge of sand that connects an island to the mainland or another island

Baymouth bar

a sandbar that completely crosses a bay, sealing it off from the ocean

Marine terrace

a wave-cut platform exposed above sea level

Which of the following is an example of "hard stabilization" designed to prevent or retard shoreline erosion?

all of the above

Which of the following shoreline features is a result of deposition?

barrier island

Which of the following mechanisms is responsible for moving tons of sediment along the shore in a zigzag pattern?

beach drift

Longshore currents and beach drift ________.

both have net movement that is parallel to the shore

A ________ is a structure designed to protect boats from large breaking waves by creating a quiet-water zone near shore.

breakwater

Waves approaching a beach at an oblique angle ________.

cause beach drift

Upwelling, the rising of water from deeper layers of the ocean, is a wind-induced movement that brings ________ water to the surface.

cold, nutrient-rich

Gyres rotate in a _____ direction in the __________.

counterclockwise, Southern Hemisphere

A ________ is a barrier built at a right angle to the beach to trap sand that is moving parallel to the shore.

groin

If uplift of the land occurs, a wave-cut platform may become a new ________.

marine terrace

The daily tidal range is of the least magnitude during ________.

neap tides

As a deep-water wave enters shallow water, the part of the wave in the shallowest water slows down. The deeper-water portion of the wave crest keeps moving at a relatively rapid speed. This wave refraction causes the entire wave crest to progressively rotate toward being ________ with the shoreline.

parallel