Deck 15: The Dynamic Ocean

Question 1

A poleward- moving ocean current is_______ .

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

Answer 1

warm

Question 2

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

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

Answer 2

Water particles move in an almost circular path.

Question 3

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

Answer 3

Yes, north Atlantic circulation is approximately the same as the long term average circulation of the Bermuda high.

Question 4

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

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

Question 5

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

A) the same salinity as the ocean waters it forms from
B) lower salinity than the ocean waters it forms from
C) higher salinity than 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 6

Fetch is_______ .

A) a method of shoreline erosion control
B) the circular pattern made by water particles when a wave passes
C) the distance that wind has traveled across open water
D) the distance between the trough of a wave and the still water level

Question 7

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

Question 8

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

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

Question 9

Thermohaline circulation is_______ .

A) 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
B) shallow circulation at low latitudes driven by surface evaporation making seawater more dense, which then sinks and drives upwelling
C) 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
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 10

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

Question 11

When Europeans first came to the new world they would typically sail south and west to Canary Islands, then west to get to the West Indies. On their return they would go north past the Leeward Islands and Canadian Maritime provinces before turning east towards Europe? Why did they choose this circular route?

A) They were attempting to follow the shortest distance, via what is called a Great Circle route.
B) The ships were affected by the Coriolis effect, so this was the natural route.
C) Although this route was against the ocean currents, it followed the prevailing wind direction.
D) This route followed both the prevailing winds and ocean currents, speeding the trip despite longer distances.

Question 12

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

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

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) There isn't really any fog; it is all just smog from too many cars in 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) Cold currents along the Texas coast inhibit fog, whereas the ocean is warm off 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

Waves begin to "feel bottom" when the depth of water is _______ . It has been likened to "stubbing your toe" and results from the wave not having enough room to be naturally contained within that depth of water.

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

Question 15

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

Question 16

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

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

Question 17

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

Question 18

What is the difference between the coastline and shoreline?

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

Question 19

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

Question 20

The black sand beaches in Hawaii are comprised of_______ .

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

Question 21

The zigzag movement of sand grains along a beach is_______ .

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

Question 22

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

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

Question 23

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

A) The onshore current from one direction piles up sand here.
B) 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.
C) The island protects the coast from rip currents, preserving the sand.
D) The tidal affects are trivial behind the island, so the sand is not swept away.

Question 24

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

Question 25

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

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

Question 26

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

A) tombolo
B) coastal barrier
C) sea stack
D) baymouth bar

Question 27

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

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

Question 28

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

Question 29

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

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

Question 30

An isolated rocky remnant of wave erosion is a_______ .

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

Question 31

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

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

Question 32

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

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

Question 33

The movement of sand parallel to the shore_______ .

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

Question 34

Rocks and sand particles on beaches become rounded rapidly because _______ .

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

Question 35

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) 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.
C) This recommendation is wrong; you should swim toward the shore as fast as you can.
D) The current is moving offshore but is confined, so by swimming parallel to shore you can swim out of the current.

Question 36

One result of wave refraction is that wave energy is concentrated_______ . Nature's forces are at play to try to even out the coastline.

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

Question 37

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

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

Question 38

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

Question 39

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

Question 40

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

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

Question 41

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 spit, formed by sand moving by longshore drift accumulating along the opening of a tidal channel
D) a barrier island, which forms an artificial beach at the front of the seawall

Question 42

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

Question 43

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 44

Chesapeake Bay and Delaware Bay are_______ .

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

Question 45

You have a beach house on the east coast of Florida. The main wave source is to the northeast. Your neighbor to the north 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- I was thinking about doing that myself but you just saved me the money.
B) Tell him he is going to destroy the beach in front of your house. If he proceeds you might need to find a lawyer.
C) Ask for clarification of what type of material he will use, to make sure it is strong enough.
D) The issue is not relevant to your property as it will not affect the beach in the region.

Question 46

Erosional retreat of an_______ leads to enlargement and extension of a wave- cut platform in the inland direction.

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

Question 47

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

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

Question 48

When the daily tidal range is least, it is called a_______ tide.

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

Question 49

Which of the following is a tidal current?

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

Question 50

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

Question 51

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

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

Question 52

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

Question 53

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

Question 54

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

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

Question 55

A spring tide occurs_______ .

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

Question 56

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

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

Question 57

Large estuaries are more common on an_______ coastline.

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

Question 58

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

Question 59

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

Question 60

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 dune field behind an active shoreline
C) on a subsiding coastline where a recent earthquake happened to uplift the seabed
D) You must be on the moon; there is nothing like that on Earth.

Question 61

When a wave impinges on a beach, the particle motion changes from_______ , producing the characteristic curl form of _______ .

A) circular to elliptical; breaking waves
B) elliptical to circular; standing waves
C) elliptical to circular; breaking waves
D) circular to elliptical; standing waves

Question 62

_______ currents are strong currents perpendicular to the coastline; swimmers can easily avoid them by swimming parallel to the shore to clear the current before then swimming back in to shore.

A) Curl
B) Spiller
C) Rip
D) Longshore

Question 63

Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option that does not fit the pattern.

A) barrier island
B) sea stack
C) tombolo
D) bar

Question 64

Upwelling zones are frequently _______ .

A) high in nutrients
B) dead zones
C) relatively warm
D) anoxic dead zones

Question 65

The east and west coasts of the North America are dominated by _______ and _______ currents, respectively.

A) cold; warm
B) warm; warm
C) warm; cold
D) cold; cold

Question 66

Prevailing winds toward a shoreline typically produce_______ .

A) downwelling
B) upwelling
C) sidewelling
D) all of these

Question 67

Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option that does not fit the pattern.

A) wave height
B) wave refraction
C) fetch
D) wave period

Question 68

When a wave arrives at an irregular shoreline, the wave front_______ as it impinges on the shore.

A) reverses course
B) becomes perpendicular to the coastline
C) is refracted
D) remains straight

Question 69

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

A) to the right
B) upward
C) downward
D) to the left

Question 70

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

A) upward
B) counterclockwise
C) clockwise
D) outward

Question 71

Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option that does not fit the pattern.

A) groin
B) beach nourishment
C) seawall
D) breakwater

Question 72

Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option that does not fit the pattern.

A) flood tide
B) tidal flat
C) neap tide
D) spring tide

Question 73

A warm current is one that is_______ .

A) moving towards one of the poles
B) above 10°C
C) above 20°C
D) moving towards the equator

Question 74

Sand transport parallel to the shoreline is common on beaches and is called_______ transport.

A) spiller
B) rip
C) longshore
D) curl

Question 75

The horizontal distance separating successive wave crests is called the wave _______ .

A) trough
B) length
C) base
D) period

Question 76

The turbulent water created by breaking waves is called_______ .

A) longshore
B) oscillation waves
C) surf
D) berm

Question 77

A baymouth bar is a_______ feature made of_______ .

A) natural; deposited sand
B) natural; eroded rock
C) manmade; emplaced rock
D) manmade; emplaced sand

Question 78

The energy that creates surface ocean currents comes from_______ .

A) prevailing winds
B) plate tectonics
C) centrifugal force
D) pull of the moon

Question 79

Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option that does not fit the pattern.

A) wave- cut cliff
B) sea arch
C) wave- cut platform
D) spit

Question 80

Density- driven ocean circulation is also called _______ circulation.

A) Gyrocline
B) Salinocline
C) Thermohaline
D) Pycnocline