Chapter 20
What term describes the bending of waves?
Refraction
________ is a strong current formed by backwash concentrated into small channels and flows rapidly away from the beach.
Rip currents
How are changes in sea level recorded in the rock record?
Rock type changes vertically
What system of measurement is used to categorize the strength of a hurricane?
Saffir-Simpson Scale
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.
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.
What is the crest of a wave?
The highest part of the wave.
Which process is directly responsible for the development of notches, cliffs, and platforms?
abrasion
At a tectonically stable shoreline, marine erosion and deposition over time will
develop a straighter and more regular coastline from an irregular coastline by eroding headlands into cliffs, filling bays with sediment, and creating spits and baymouth bars.
The direction that sediment is traveling along a coast is called the direction.
downstream
A(n) ________ coast will be created when sea level falls or the land is uplifted.
emergent
Which central part of a hurricane is characterized by a calm zone where precipitation and winds cease?
eye
In order to produce longshore drift, the direction of waves must not be to the coast.
perpendicular
Which of the following efforts to counteract beach erosion do coastal scientists consider the best permanent option?
relocation of at-risk buildings from the beach
Which rock types would you expect to see deposited if sea level rises and then falls?
sand covered by mud covered by sand
Which feature results from the collapse of a sea arch?
sea stack
Landforms associated with longshore drift form where the is plentiful enough to create them.
sediment
The ________ is the line that marks the contact between land and sea.
shoreline
Which of the following depositional features is produced by longshore transport?
spit
elongated ridge of sand projecting out into a bay.
spit
Waves hitting at an angle and then bending around features of the coast is known as
wave refraction
Which of the following is a characteristic example of an emergent coastline?
wave-cut platform
bench created by waves crashing into a cliff.
Wave-cut platform
the horizontal distance between successive crests.
Wavelength
How shallow must the ocean floor be for waves to start to "feel bottom" for a wave set with a wavelength of 20 feet?
Waves will "feel bottom" when the ocean floor is 10 feet below the surface
When does the spring tide occur?
When the Sun and the Moon are in alignment
In a , wind speeds are below 38 miles per hour.
tropical depression
A disorganized array of clouds and thunderstorms with little or no rotation is known as a
tropical disturbance.
Half or more of (s) eventually become hurricanes.
tropical storm
If winds are between 38 and 74 miles per hour, the condition is called a
tropical storm
The storm is given a name once it reaches the stage.
tropical storm
Hurricanes get their energy from ________ water.
warm
If the wavelength of a set of waves is 20 feet long, how deep is the wave base?
10 feet below the surface
If the distance from one wave crest to the next is 10 ft., what will the depth to the wave base be
5 ft
What is a beach, and how does a beach face differ from a berm?
A beach is an accumulation of sediment found along the landward margin of an ocean or a lake. A beach face is the wet, sloping surface that extends from the berm to the shoreline; a berm is a relatively flat platform that is usually composed of sand adjacent to coastal dunes or cliffs.
What is a berm?
A flat-topped platform of sand adjacent to dunes or cliffs
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?
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.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.
What is the fetch?
A large area of open water over which wind blows to generate waves
How is a marine terrace related to a wave-cut platform?
A marine terrace is a wave-cut platform that has been uplifted above sea level by tectonic forces.
Which of the following describes the movement of air in a hurricane in the Northern Hemisphere?
Air moves up from the surface in a counterclockwise direction.
a sandbar that completely crosses a bay.
Baymouth bar
Which beach stabilization technique requires dumping many truckloads of sand on a beach to build it up?
Beach nourishment
As the quantity of energy transferred to the wave increases, what will happen to the height and the steepness of the wave?
Both the wave height and steepness increase.
What is the wavelength?
The distance between consecutive wave crests or troughs.
Imagine that it is late September, and a category 5 storm, Hurricane Gaston, is projected to make landfall along the path shown on the accompanying map. If the storm nears the Dallas-Fort Worth area, what poses the biggest threat to life and property?
Heavy rainstorms may hit Dallas-Fort Worth.Flooding as a result of heavy rains from the storm.
Where do hurricanes that hit the East Coast of the United States form? In which direction do they travel?
Hurricanes form in the Atlantic Ocean north of the equator and move in a northwest direction.
Which of the following statements about hurricanes is true?
Hurricanes lose energy when moving over land.
Which of the options below are correct descriptions of hard stabilization of beaches?
Jetties, which are built in pairs at river entrances, aim to keep sand from depositing in the channel. An effect of jetties is the erosion of sand on their downcurrent sides and the deposition of sand on their upcurrent sides 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 an artificial coastal feature?
Jetty
Which of the following is responsible for moving tons of sediment parallel to the shore?
Longshore currents
________ form when waves that approach the beach at an angle and produce a net current direction that is parallel to the shore, resulting in beach drift.
Longshore currents
Which of the following areas consists of narrow beaches backed by steep cliffs and mountain ranges?
Pacific Coast
How did sea level change to produce this sequence of rocks?[TOP: Limestone, MID1: Mud, MID2: Sand, BOTTOM: Shale]
Sea level fell and then rose.
How did sea level change to produce this sequence of rocks?[TOP: Mud, MID1: Limestone, MID2: Mud, BOTTOM: Limestone]
Sea level fell, then rose, and then fell again.
How did sea level change to produce this sequence of rocks?[TOP: Sand, MID: Mud, BOTTOM: Limestone] Try making a sketch and labeling it.
Sea level fell.
How did sea level change to produce this sequence of rocks?[TOP: Sand, MID: Mud, BOTTOM: Limestone]
Sea level rose.
an isolated rock column left behind after the collapse of a sea arch.
Sea stack
How would you expect sediment to change as you walk from shore into the ocean?
Sediment generally changes from sand to mud to limestone.
During which month are hurricanes most likely to occur on the east coast of the United States?
September
What are the three main categories of damage caused by hurricanes, and which one of them causes both, the highest monitary cost and results in more deaths?
Storm surge, wind damage, and inland flooding; with storm surge being the most damaging and deadly.
If you happen to be caught in a rip current, what is the best way to get to safety?
Swim parallel to the shore.
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 refraction?
The bending of waves due to a change in wave velocity.
A set of waves are moving from east to west. Assuming the boat is in deep water, which of the following would describe the motion of a boat during the passage of these waves?
The boat would move up and down in the water
What is the relationship between wave base and wavelength?
The depth of the wave base is one-half the wavelength of the waves.
What is the wave base?
The lower limit of wave-induced motion in water.
What is the trough of a wave?
The lowest part of the wave.
Which side of an advancing hurricane in the Northern Hemisphere has the strongest winds and highest storm surge—right or left? Why?
The right side of the hurricane would have the strongest winds and highest storm surge because on this side the winds blow in the same direction as the storm's movement. In contrast, the winds on the left side of the hurricane blow in the direction opposite of the storm's direction of movement.
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 decrease, and the wave's height increases.
What is the wave period?
The time it takes for one wavelength of a wave to pass a particular point/
Which circumstance will force a wave displaying circular orbital motion to slow down at the base, which allows the wave to break?
The wave feels bottom with shallower depth.
Why do ocean waves bend around headlands?
The waves are moving more slowly just in front of the headland, causing the waves to bend.
ridge of sand that connects the mainland to an island.
Tombolo
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 increases as depth decreases.
When a headland of resistant bedrock extends out into the ocean, which statement best describes wave action in proximity to the headland?
Wave energy is focused on the headland.
−−the vertical distance between the trough and the crest.
Wave height
the time it takes for one full wave to pass a given point.
Wave period
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 deposition in adjacent bays.
Which of the following coastal features is not a characteristic of a submergent coastline?
Wave-cut platform
Which of the following distances represents one wavelength of the wave set drawn below?
a-c
A forms when longshore drift creates a ridge of sand separating a waterway from the ocean.
baymouth bar
Why is the shoreline described as being an interface?
because the shoreline is a dynamic boundary among air, land, and sea
A ________ is a hard shoreline stabilization feature, detached from the shoreline, that protects shorelines from the pounding of waves by creating an area of quiet water behind it.
breakwater
Which type of hard stabilization increases beach erosion? CHOOSE ALL THAT APPLY
breakwater groin jetty
. In order to be considered a , wind speeds must be in excess of 74 miles per hour.
hurricane
. When there is longshore drift, the overall direction of sand transport is to the coast..
parallel
A(n) ________ coast will be created when sea level rises or the land subsides.
submergent
Which of the below locations within the coastal zone is hardly, if ever, reached by waves?
the berm
What is the wave height?
the distance between the highest and lowest part of the wave
What factors determine the height, length, and period of a wave?
the speed of the wind the length of time that the wind has blown the distance that the wind has traveled across open water
