Deck 15: The Dynamic Ocean

Question 1

A poleward-moving ocean current is ________.

A)warm
B)cold
C)warm only in the Northern Hemisphere
D)warm only in the Southern Hemisphere

Answer 1

A

Question 2

When Europeans first came to the new world they would typically sail south and west to Canary Islands,then sail west to get to the West Indies and Spanish main.On their return,however,they would go north to the "Leeward Islands" of the Caribbean,to the Bahamas,Bermuda,etc.Why did they take this odd route rather than sail straight?

A)The ships were affected by the Coriolis effect,so this was the natural route.
B)Although this route was against the ocean currents,it followed the prevailing wind direction so sailing ships could follow this route downwind-hence the name "Leeward Islands."
C)They were attempting to follow the shortest distance,via what is called a great circle route.
D)This route followed both the prevailing winds and ocean currents,speeding the trip despite longer distances.

Answer 2

D

Question 3

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

A)salinity variations
B)Coriolis effect
C)prevailing winds
D)density differences

Answer 3

C

Question 4

The height,length,and period of a wave depend upon ________.

A)the length of time the wind has blown
B)the wind speed
C)the fetch
D)all of these

Question 5

Why is it warmer in most of Europe than in northern California even though both are on the east side of an ocean and Europe is at higher latitude than California?

A)California is affected by a cold offshore current,whereas Europe has the warm north Atlantic current,the continuation of the Gulf Stream.
B)California weather is affected by the coastal mountains,which hold cold air along the west coast.
C)Californians are just wimps; it really is warmer than Europe.
D)The famous California surf stirs up the surface water,bringing deeper colder ocean water to the surface.

Question 6

In the Cretaceous period of earth history there is clear evidence that the climate was much warmer than today.It was so warm that areas near the pole had tropical vegetation like palm trees,and there was almost certainly no sea ice and glaciers probably only existed at very high altitude.This produced widespread anoxia (stagnant,no-oxygen condition)on the floor of the oceans.From your knowledge of ocean circulation,which of the following explanations could account for the anoxia?

A)The greenhouse affect made planktonic algae grow so fast that they filled the ocean with algae,stagnating the ocean.
B)The greenhouse affect led to so much CO2 in the atmosphere that animals all died from lack of oxygen,stagnating the oceans.
C)The lack of polar sea ice stopped any thermohaline deep circulation in the oceans,stratifying the water column to produce anoxia in the deep sea.
D)The water got so warm it couldn't hold any oxygen,stagnating the water column.

Question 7

El Niño is a well-known weather phenomenon.In Ecuador and Peru,fisherman knew about the phenomena long before it was well known because their fishing would be very poor during El Niño conditions.Normally Peru and Ecuador have a remarkable fishery because there is a prominent upwelling along the coast which produces plantonic blooms that feed the entire ecosystem.This upwelling is driven by surface wind conditions.From your knowledge of currents and wind conditions,which of the following happens during El Niño conditions in this area?

A)The winds shift from south to north,along the coast,to west to east,across the coast.
B)The winds change from east to west (offshore flow)to onshore flow or weak winds during El Niño conditions.
C)The winds shift from west to east (onshore flow)to offshore flow (east to west)during El Niño conditions.
D)The winds shift from prevailing southwesterlies to stagnant,doldrum conditions during El Niño.

Question 8

When prevailing winds blow from onshore to offshore,what generally happens?

A)The winds cause offshore surface water to flow away from shore,forcing deeper water to rise to the surface.
B)The dry conditions from the land evaporate surface waters,making them more dense due to salinity increase,and they sink.
C)The wind drives a longshore current,which draws cold air from higher latitudes,producing a cold climate.
D)The wind drives the water away from shore,forcing the water to descend in a downwelling zone.

Question 9

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

A)equal to its wave base
B)equal to the wavelength
C)twice as great as the wavelength
D)three times as great as the wavelength

Question 10

The black sand beaches in Hawaii are comprised of ________.

A)fragments of black coral
B)fragments of basaltic volcanic rock
C)fragments of obsidian glass
D)ground up bottle and other debris placed there by Hawaii tourist bureaus.There is not natural sand in Hawaii because there is no quartz

Question 11

When sea ice forms in high latitudes,the sea ice has ________.

A)lower salinity than the ocean waters it forms from
B)higher salinity than the ocean waters it forms from
C)the same salinity as the ocean waters it forms from
D)It depends on the temperature.If conditions are far below freezing,the salinity is the same as the adjacent seawater; if it is close to freezing,the ice is essentially fresh water

Question 12

You are body surfing in modest waves that are breaking just offshore.A particularly big one catches you off guard,flips you over and over,and deposits you on the shore.As you lie there in the sand,you think,hey,I just landed on ________.

A)the backshore
B)the beachface
C)a coastal dune
D)a nearshore bar (not the kind that serves drinks)

Question 13

Coastal California is famous for fog and smog (fog mixed with smoke).Why is the California coast foggy/smoggy,whereas Houston,Texas,which is at similar latitude,might get occasional smog from too many cars,but fog is relatively rare?

A)Cold currents along the Texas coast inhibit fog,whereas the ocean is warm off California.
B)The ocean is warm off the Texas coast,but a cold current running offshore California generates fog when the cold,moist air is drawn ashore by a sea breeze.
C)There isn't really any fog; it is all just smog from too many cars in California.
D)Warm air in Texas rises to make clouds and not fog,whereas in California cold water from the ocean mixes with warm water from the land to generate fog.

Question 14

What is the difference between the coastline and shoreline?

A)The coastline is the landward limit of ocean-related landforms,and the shoreline is the ephemeral line that marks the interface between land and sea.
B)The coast is the landward limit of ocean-related landforms,the coastline is the line that separates the coast from the shore,and the shoreline is the ephemeral line that marks the interface between land and sea.
C)The shoreline is the landward limit of ocean-related landforms,and the coastline is the interface between land and sea.
D)The shoreline is the low-tide line,and the coastline is the high-tide line.

Question 15

Which of the following is correct regarding a wave in the open ocean?

A)Water particles move in an almost circular path.
B)Such waves are called waves of oscillation.
C)Waves do not exist in the open ocean - only near the coast.
D)None of these

Question 16

The Bermuda high is a large,persistent high pressure system centered roughly on the island of Bermuda in the mid-Atlantic,hence the name.Air circulates clockwise around high pressure systems because of the Coriolis effect.Is there any connection between Atlantic ocean currents and this weather feature?

A)No,the North Atlantic Ocean circulation is counterclockwise,like all Northern Hemisphere gyres.
B)No,north Atlantic circulation is clockwise,but the connections to the Bermuda high circulation are only circumstantial; the ocean circulation is a bigger feature.
C)Yes,north Atlantic circulation is approximately the same as the long term average circulation of the Bermuda high.
D)Yes,they are crudely correlated,but the weather systems are so chaotic that the correlation is not meaningful.

Question 17

Thermohaline circulation is ________.

A)shallow circulation at low latitudes driven by surface evaporation making seawater more dense,which then sinks and drives upwelling
B)deep circulation of water driven entirely by cold,saline water descending to the ocean floor at the poles and flowing along the bottom of the ocean
C)deep circulation of water driven by a combination of cold temperature and high density related to high salinity from formation of sea ice,producing descending high density waters that flow southward to equatorial regions
D)the circulation that occurs in shallow,evaporate basins when salt begins to crystallize,releasing heat by latent heat of fusion and heating the water mass,forcing shallow convection in the water column

Question 18

You are walking along the shoreline but the material under your feet isn't sand,but instead is large cobbles and you occasionally have to scramble around small boulders.You are on ________,

A)a beach
B)a coastal dune
C)a wave cut terrace
D)a coral reef shoreface

Question 19

If you are a sunbather sitting high and dry on a beach,sipping your drink and watching the waves roll in,you are on ________.

A)the foreshore
B)a backshore berm
C)the shoreline
D)any of the above

Question 20

Because of the Coriolis effect,surface ocean currents are deflected to the ________ of their path of motion in the Northern Hemisphere.

A)right
B)left
C)west
D)east

Question 21

One result of wave refraction is that wave energy is concentrated ________.

A)on headlands projecting into the water
B)in the recessed areas between headlands
C)in estuaries
D)none of the above

Question 22

You are in a ship in deep water offshore from a large island.There is a heavy swell from the northeast and the island is to the southwest of you when the ship capsizes.Based on the wave direction,what should you do?

A)Just float,the waves will drive you to shore since the waves are moving toward the island.
B)Swim like crazy; the waves are going to carry you away from shore.
C)Swim toward the island; the waves aren't going to take you anywhere.
D)Swim in a circle because that is what the waves are doing.

Question 23

A north south oriented shoreline has land to the east and the major storm waves arrive from the southwest.A headland abuts westward along the shoreline and exposes a distinctive black basalt that is rapidly eroded by waves pounding the coast.Where would you expect to find black sand derived from this headland?

A)on the beach to the north of the headland
B)on the beach to the south of the headland
C)immediately offshore of the headland
D)only in pocket beaches along the headland

Question 24

A ridge of sand projecting into a bay and often having a hooked end is a ________.

A)spit
B)jetty
C)groin
D)sea stack

Question 25

The zigzag movement of sand grains along a beach is ________.

A)caused by obliquely breaking waves
B)called beach drift
C)very unusual and seldom occurs
D)both caused by obliquely breaking waves and called beach drift

Question 26

The presence of which one of the following would indicate that the land had been uplifted or that sea level had fallen?

A)an estuary
B)a sea stack
C)elevated marine terrace
D)a tombolo

Question 27

Rocks and sand on beaches become rounded rapidly because ________.

A)rip currents move the sand offshore rapidly,abrading the fragments
B)the swash action of waves rolls loose material up and down the beach,where it is abraded rapidly to produce rounded grains
C)Beach sand is mostly calcium carbonate from reefs and so gets rounded easily
D)There is nothing particularly prominent in beaches that produces more rounding than other sedimentary processes.

Question 28

When waves reach shallow water,they are often bent and tend to become parallel to the shore.This process is termed ________.

A)oscillation
B)refraction
C)translation
D)reflection

Question 29

Which one of the following is a landform created by wave erosion?

A)spit
B)estuary
C)tombolo
D)sea arch

Question 30

Anyone who has ever gone swimming in heavy surf will tell you that if a wave is about to crash over you,the best thing to do is dive down,under the wave.Why does this keep you from being swept up in the wave,like being in a washing machine?

A)You dive into the base of the zone of circular motion associated with the wave.
B)You dive below the shoreward moving part of the elliptical particle motion of the wave.
C)You dive into the rip current,which will carry you out to sea.
D)You get carried sideways by a longshore current,which is better than being beaten up by the breaking wave.

Question 31

The movement of sand parallel to the shore ________.

A)is created by waves approaching at an oblique angle
B)may create spits
C)is achieved by longshore currents
D)all of the above

Question 32

Fetch is ________.

A)a method of shoreline erosion control
B)the distance between the trough of a wave and the still water level
C)the circular pattern made by water particles when a wave passes
D)none of these

Question 33

An isolated remnant of wave erosion is a ________.

A)spit
B)jetty
C)groin
D)sea stack

Question 34

When waves crash against a sea cliff,what is the main process that erodes the cliff?

A)abrasion by rocks flung against the cliff by the waves
B)water flowing upward against the cliff,washing the cliff face of loose debris
C)hydraulic pressure driven by the waves forcing water,air,or both into cracks,dislodging rocks from the cliff
D)impact of the wave causing vibrations that trigger landslides

Question 35

A sandbar that completely crosses a bay,sealing it off from the open ocean,is a ________.

A)sea stack
B)tombolo
C)coastal barrier
D)none of these

Question 36

You are swimming with your buddies on a beach in the surf.You leave your cooler and supplies on the beach,and after a half hour you swim back to shore,but your stuff isn't there.You look along the beach and see your cooler 200 m down the beach.How did that happen?

A)You and your buddies must have gotten caught in a rip current without knowing it.
B)You and your buddies must have been swimming parallel to the shore without thinking about it.
C)You and your buddies must have had too many and just lost track of where you were.
D)You and your buddies were affected by the longshore current and drifted with it along the coast.

Question 37

A sand ridge connecting an island to the mainland or to another island is a ________.

A)jetty
B)tombolo
C)breakwater
D)sea stack

Question 38

The movement of water within the surf zone that parallels the shore is termed ________.

A)tidal current
B)salinity current
C)beach drift
D)longshore current

Question 39

Rip currents are dreaded by surf swimmers everywhere.The standard recommendation for swimmers is if you get caught in a rip current,swim parallel to the shore.Why?

A)It will carry you in the longshore current which will take you ashore.
B)The current is moving offshore but is confined,so by swimming parallel to shore you can swim out of the current.
C)This recommendation is wrong; you should swim toward the shore as fast as you can.
D)This recommendation is wrong; you should swim with the current and wait for it to die away,then swim to shore because the currents dissipate quickly.

Question 40

Fetch refers to ________.

A)the beachfront area where rapid erosion is taking place
B)a large expanse of open water over which the wind blows and generates waves
C)the rotational movements of water particles beneath a passing surface wave
D)ocean currents moving parallel to the beach

Question 41

You are standing above a 20 m high sea cliff with a large beach below you.All around you is a flat surface with thin soil on a rocky base.In the distance you see another flat bench but it is about 30 m higher than you are.Where are you?

A)on an uplifted wave-cut terrace along an emergent coastline
B)on a subsiding coastline where a recent earthquake happened to uplift the seabed
C)on a dune field behind an active shoreline
D)You must be on the moon; there is nothing like that on Earth.

Question 42

Construction of a breakwater produces the same effect as what kind of natural coastal structure?

A)a sea cliff producing erosion at the base of the sea cliff (i.e.breakwater)
B)an island offshore breaking waves and trapping sand behind to form a tombolo
C)a barrier island,which forms an artificial beach at the front of the breakwater
D)a spit,formed by sand moving by longshore drift accumulating along the opening of a tidal channel

Question 43

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

A)wave-cut tombolo
B)wave-cut cliff
C)wave-cut barrier beach
D)offshore,wave-cut,breakwater bar

Question 44

Hurricane Sandy produced some of the greatest destruction along the New Jersey coast in communities situated along narrow strips of land between the beach and a coastal lagoon to the west.These communities were vulnerable because they were built on low-lying terrane of ________.

A)a barrier island
B)a wave-cut platform
C)an eroding sea cliff
D)spits and tombolos

Question 45

Large estuaries are more common on a(n)________ coastline.

A)submergent
B)emergent
C)stable
D)retreating

Question 46

Chesapeake Bay and Delaware Bay are ________.

A)associated with a submergent coast
B)former river valleys that were flooded by a rise in sea level
C)excellent examples of large estuaries
D)all of the above

Question 47

Construction of a seawall produces an effect analogous to what kind of natural coastal feature?

A)a sea cliff producing erosion at the base of the sea cliff (i.e.,the seawall)
B)an island offshore breaking waves and trapping sand behind to form a tombolo
C)a barrier island,which forms an artificial beach at the front of the seawall
D)a spit,formed by sand moving by longshore drift accumulating along the opening of a tidal channel

Question 48

You are walking along a rugged coastline in British Columbia,Canada.As the tide goes out you realize there is a beautiful flat surface that is nearly as smooth as a highway and underlain by 1-2cm of gravel sitting on solid rock.The tide has exposed a ________.

A)sea stack
B)tombolo
C)wave-cut platform
D)spit

Question 49

What kind of man made feature would likely lead to sand loss on a beach regardless of active margin (west coast North America)versus passive margin (east and Gulf coast of North America)setting for the coastline?

A)dam construction
B)building too close to sea-cliff and allowing urban runoff to seep into the rocks along the cliff
C)constructing a highway bridge over a bay mouth
D)construction of offshore oil platforms

Question 50

The town of Grand Isle,Louisiana is built on a barrier island that has been shrinking for decades.They have tried the following approaches to protect the island from coastal erosion.Which of these is not a feature intended to simulate natural barrier island beach processes?

A)offshore sand dredging and deposition to rebuild the beach
B)placement of large concrete donuts on the seabed in the surf zone
C)placement of groins
D)construction of artificial dunes and planting coastal grasses on the dunes

Question 51

You run a business selling bait to fisherman near the tip of a large sand spit.A sand and gravel company owns coastal property up the coast from you-the other direction from the tip of the spit.The sand and gravel company plans to dredge sand from the beach and mine the sand and gravel from a seacliff that is eroding in the coastal zone.What should be your opinion on this sand and gravel operation?

A)You should go into business with the sand and gravel operator and have them deliver sand to your beach to help tourism.
B)There is no problem; the operator will increase sediment supply to the beach which will help your little sand spit.
C)There is no problem; the longshore drift is away from you.It is people up the coast who should be concerned.
D)You should look for a lawyer or a real estate agent because the sand and gravel operation will destroy your sand spit in time

Question 52

You are interested in buying a piece of land overlooking the sea.You find a place atop a 50m high sea cliff.The lot is only about 30m wide but is 200m long parallel to the coast,so you think you are getting a large expanse of the coastline.What would be the most important thing to look for in considering this purchase?

A)the view
B)quality of the beach
C)the stability of the sea cliff,rock type,etc.
D)accessibility of the beach

Question 53

What direction is the longshore current in the area pictured below?

A)left to right
B)right to left
C)top to bottom
D)impossible to tell from this figure

Question 54

Why would sand be deposited behind a small island to form a spit or tombolo?

A)The tidal affects are trivial behind the island,so the sand is not swept away.
B)The island protects the coast from rip currents,preserving the sand.
C)Waves refract around the island and the wave energy is dissipated on the island,allowing quiescent water behind,and sand drift to accumulate behind the island.
D)The onshore current from one direction piles up sand here.

Question 55

You have a fancy beach house in the east coast of Florida.The main wave source is to the northeast.Your neighbor to the south of you is having problems with beach erosion and storm waves often come under his house.So he decides to build a groin and he tells you it is for the benefit of the neighborhood.What should you respond to his comment?

A)Thanks buddy,I was thinking about doing that myself but you just saved me the money.
B)Ask for clarification of what type of material he will use,to make sure it is strong enough.
C)Tell him no way.He is going to destroy the beach in front of your house.If he proceeds you might need to find a lawyer.
D)Don't worry,be happy,you're on the beach.It won't hurt anything.

Question 56

Horn Island is a small island about 10 km offshore from Biloxi,Mississippi,that is about 20 km long and 1 km wide.What are features like Horn Island called?

A)beaches
B)reefs
C)sand spits
D)barrier islands

Question 57

Which one of the following structures is built to protect boats from large breaking waves?

A)jetty
B)groin
C)breakwater
D)seawall

Question 58

Which of the following is designed to prevent or retard shoreline erosion?

A)groin
B)beach nourishment
C)seawall
D)all of these

Question 59

A flat,bench-like surface cut in rock along a coast is a ________.

A)sea stack
B)tombolo
C)wave-cut platform
D)spit

Question 60

If you go to a beach in the continental United States and you are standing on a long,flat strand of sand,and you look away from the open ocean and see only a few low sand dunes and then a large,open waterway,where are you?

A)on a surfing beach in California
B)on a the Oregon coast at the mouth of river
C)on a barrier island on the Florida Gulf Coast
D)You must be on a Pacific Island; there is nothing like that on U.S.coastlines.

Question 61

Prevailing winds toward a shoreline typically produce upwelling.

Question 62

The east and west coasts of the North America have very different temperatures at the same latitude primarily because of ocean currents.

Question 63

You land your inflatable boat on a sandbar at high tide in Southeast Alaska,which has a large semi-diurnal tide.You intend to be away from the boat for 12 hours,but come back early after only 8 hours.Your boat is,unfortunately,400m from shore.How long will you have to wait to be able to use your boat (assuming you can't carry it)?

A)12 hours and 25 minutes
B)6 hours and 12 minutes
C)6 hours
D)4 hours and 25 minutes

Question 64

sea stack bar tombolo barrier island

Question 65

A poleward-moving ocean current is considered a warm current.

Question 66

Upwelling zones are frequently dead zones because high nutrients produce biologic activity leading to anoxic water conditions.

Question 67

The Coriolis effect causes ocean currents in the Southern Hemisphere to be deflected to the right of their path of motion.

Question 68

When you are swimming in the surf and ride a wave into the limit of the wave washup,you are deposited on the shoreline.

Question 69

The daily tidal range is GREATEST during what period of the lunar cycle?

A)full moon
B)first quarter
C)new moon
D)A and C

Question 70

breakwater groin seawall beach nourishment

Question 71

Which of the following is a tidal current?

A)spring tide
B)flood tide
C)ebb tide
D)both flood and ebb tide

Question 72

The shoreline and the coastline are defined as the same thing.

Question 73

spring tide flood tide neap tide tidal flat

Question 74

When the daily tidal range is LEAST,it is called a ________ tide.

A)spring
B)ebb
C)neap
D)none of these

Question 75

The energy that creates surface ocean currents comes from prevailing winds.

Question 76

A spring tide occurs ________.

A)once a year at the first full moon after the vernal equinox
B)twice a year at the new or full moon closest to the vernal and autumnal equinox
C)about 26 times per year,at every full and new moon
D)once a month,or 12 times a year

Question 77

Surface ocean circulation is also called thermohaline circulation.

Question 78

wave height wave period wave refraction fetch

Question 79

wave-cut cliff wave-cut platform sea arch spit

Question 80

As a fluid (air or water)moves toward an area of lower pressure in the Northern Hemisphere,the Coriolis effect results in counterclockwise circulation.