OCE1001 chpt 3

t

The Pacific Ring of Fire is the seismically active area along the margins of the Pacific Ocean where earthquakes and volcanoes are common. (t/f)

f

The three major provinces of the ocean floor are continental margins, deep-ocean basins, and submarine canyons. (t/f)

d

The greatest proportion of Earth's surface lies in this elevation/depth interval. a) 0-1,000 m above sea level b) 5,000-6,000 m below sea level c) 1,000-2,000 m above sea level d) 4,000-5,000 m below sea level e) 3,000-4,000 m below sea level

f

Turbidity currents are highly erosive and are thought to be responsible for the creation of deep-sea trenches. (t/f)

d

Volcanic peaks on the deep-ocean floor with conical tops are called: a) oceanic ridges. b) submarine canyons. c) oceanic trenches. d) seamounts. e) tablemounts.

b

What are turbidity currents? a) dense mixtures of sand, mud, and other debris that move at low speeds down submarine canyons b) dense mixtures of sand, mud, and other debris that move at high speeds down submarine canyons c) dense mixtures of sand, mud, and other debris that move at high speeds up submarine canyons d) dense mixtures of sand, mud, and other debris that move at low speeds up submarine canyons

a,b,c,e

What process(es) affect the shape and structure of continental shelves? a) erosion of sediment b) eposition of sediment c) large fluctuations in sea level d) the creation of pillow lavas along the mid-ocean ridge e) major climate changes, such as ice ages

a

What statement correctly distinguishes an ocean trench from a submarine canyon? a) Trenches descend deep beyond the abyssal plains. Submarine canyons are part of the shallower continental margins. b) Trenches are formed by erosive currents. Submarine canyons are drowned, ancient river valleys. c) Trenches are only located along active margins. Submarine canyons are only located along passive margins. d) Trenches occur only in the Pacific Ocean. Submarine canyons occur in all oceans

d

Directly seaward of the continental shelf is a more steeply sloping region called the: a) continental rise. b) abyssal plain. c) mid-ocean ridge. d) continental slope. e) trench.

b

A ship's fathometer (an echo sounder) transmits a sound pulse and records the return of an echo 7.4 seconds later. If the speed of sound in water is 1,500 m/second, what is the water depth in meters? a) 4,550 meters b) 5,550 meters c) 7,400 meters d) 11,100 meters e) 3,000 meters

b

Extending from the base of the continental rises into the deep-ocean basins are flat depositional surfaces called: a) continental shelves. b) abyssal plains. c) tablemounts. d) continental slopes. e) abyssal hills.

b

Identify the major feature of a slow-spreading mid-ocean ridge. a) trench b) rift valley c) volcanic arc d) oceanic rise e) submarine canyon

e

All the following are considered part of the continental margin except the: a) continental slope. b) submarine canyon. c) continental rise. d) continental shelf. e) fracture zone.

t

Black smokers are hydrothermal vents that discharge superheated water with high concentrations of metal sulfides. (t/f)

c

Can you explain why atolls extend from the surface of the ocean down to great depths into the sea? Corals, which make up these ring-shaped structures, can only live where water is warmed and illuminated by sunlight, no more than approximately 45 meters deep. How do you explain an atoll that extends thousands of meters deep? a) Corals deep in the ocean can survive because they are warmed by seamounts instead of the sun. The atoll consists of layers of coral reef alive at the surface and near seamount vents. b) Sea currents circulate nutrients to the reef deeper than 45 meters and provide a rigid force to keep the coral reef at the surface. c) The coral reef once formed around an active volcano. The reef became a barrier reef, with hard skeletons of previous colonies acting as the scaffolding for new ones on top. The volcano gradually sank into sea, moving with the plate it rested on, as the coral continued to grow upward, leaving the atoll as a ring structure at the top. d) Pieces of coral from other reefs are carried farther out into the ocean, where they act like seeds and start new coral reefs. These corals quickly grow up into the warmer parts of the ocean where they thrive and form round atolls as a means of trapping warmer water around them.

d

Characteristics of active continental margins include all the following except: a) thin sediment accumulation. b) narrow, relatively steep continental shelves. c) deep-sea trenches. d) broad continental shelves. e) volcanic and earthquake activity.

b

How do turbidity currents affect canyons? a) Turbidity currents erode material from canyons as currents move upslope. b) Turbidity currents erode material from canyons as currents move downslope. c) Turbidity currents deposit material in canyons as currents move upslope. d) Turbidity currents deposit material in canyons as currents move downslope.

c

How often do turbidity currents occur? a) somewhat frequently b) very frequently c) infrequently

t

Hydrothermal vents are often associated with central rift valleys along the oceanic ridge and rise system. (t/f)

f

Hydrothermal vents are seafloor cold seeps with high concentrations of sulfur and salts. (t/f)

d

Imagine you are a geological oceanographer. As an expert, you are asked by a student to recommend the technique that would produce the most detailed map of a deep-water seamount near Hawaii. Which instrument would you recommend? a) precision depth recorder b) multibeam echo sounder c) satellite altimetry d) side-scan sonar e) seismic reflection

d

In comparison with other ocean basins, major sedimentary features such as continental rises and abyssal plains are relatively rare in the Pacific. The primary reason for their scarcity in the Pacific is that __________. a) the Pacific Ocean is too large for those features to form b) the numerous volcanoes of the Pacific rim and islands prevent normal sedimentation c) turbidity currents are rare in the Pacific, so little sediment is carried down the continental slopes d) sediment is trapped within the trenches of the convergent plate boundaries ringing the Pacific e) rivers do not carry much sediment into the Pacific

b

Match the term with the appropriate phrase. abyssal plain a) a generally flat zone extending from the shore to the shelf break b) flat depositional surfaces that cover extensive portions of the deep-ocean basins c) narrow and deep valleys on continental slopes d) shallow-water areas close to continents e) deep linear scars on the deep-ocean floor caused by plate convergence

b

Match the term with the appropriate phrase. continental shelf a) shallow-water areas close to continents b) a generally flat zone extending from the shore to the shelf break c) deep linear scars on the deep-ocean floor caused by plate convergence d) flat depositional surfaces that cover extensive portions of the deep-ocean basins e) narrow and deep valleys on continental slopes

b

Match the term with the appropriate phrase. ocean trench a) flat depositional surfaces that cover extensive portions of the deep-ocean basins b) deep linear scars on the deep-ocean floor caused by plate convergence c) a generally flat zone extending from the shore to the shelf break d) narrow and deep valleys on continental slopes e) shallow-water areas close to continents

a

Match the term with the appropriate phrase. submarine canyon a) narrow and deep valleys on continental slopes b) shallow-water areas close to continents c) a generally flat zone extending from the shore to the shelf break d) deep linear scars on the deep-ocean floor caused by plate convergence e) flat depositional surfaces that cover extensive portions of the deep-ocean basins

b

Measurement of ocean floor bathymetry from satellites relies on ___________. a) calculations of how much water versus rock there is at any ocean location b) sea surface elevation, which varies depending on the shape of the underlying sea floor c) density differences of ocean waters d) water temperature, which is higher in areas of shallow ocean waters and can easily be detected by satellites e) water flows off the high areas and into the low areas, making the ocean surface topography the exact inverse of the shape of the sea floor

continental volcanic arcs, volcanic island arcs

Melt from the subducting plate rises to the surface, erupts through the crust on the overriding plate and forms____________ on continents, or ____________ in the ocean.

b

Most ocean floor features owe their origins to _________. a) erosion and weathering b) plate tectonic processes c) biological activity d) extreme pressure at depth e) ocean current activity

b

Nearly all oceanic islands are __________. (Choose the best answer.) a) parts of continents separated from continents b) volcanic in origin c) formed at high-standing areas of mid-ocean ridges d) formed at hot spots as lithospheric plates pass over mantle plumes e) parts of volcanic island arcs

e

New lithosphere is produced in association with: a) hydrothermal vents. b) deep-sea trenches. c) fracture zones. d) transform faults. e) oceanic ridges.

mid-ocean ridges

Oceanic crust spreads at _____________, creating new crust and slowly enlarging the ocean basin.

b,e

Of the following items, which is/are associated with a passive continental margin? a) a deep-ocean trench b) a wide continental shelf c) an abundance of earthquake activity d) volcanic eruptions and pillow lavas e) turbidity currents, which are initiated here and flow down submarine canyons

a,b,c,d

Of the following statements about Earth's hypsographic curve (figure shown below), which is/are true? a) The hypsographic curve shows that a majority of the ocean floor is below 4 kilometers deep. b) The hypsographic curve shows that a majority of the exposed land is below 1 kilometer in elevation. c) The hypsographic curve shows the percentage of Earth's surface area that is covered by ocean waters. d) The hypsographic curve shows that the average depth of the ocean is about four times the average height of the continents. e) The hypsographic curve shows the amount of water in the oceans.

a,c,d,e

Of the following statements about mapping the ocean floor, which is/are true? Of the following statements about mapping the ocean floor, which is/are true? a) Only 5% of the ocean floor has been mapped as accurately as the Moon. b) The entire ocean floor has been accurately mapped using sonar from ships. c) Radar altimeters on satellites have collected data on sea surface elevation that help produce maps of the sea floor. d) The ocean's great depth and opaque character have hindered mapping efforts. e) There are large areas of the sea floor that remain unmapped by sonar.

b

Older lithosphere is destroyed in association with: a) fracture zones. b) deep-sea trenches. c) hydrothermal vents. d) mid-ocean ridges. e) spreading centers.

a,c,e

On a deep-sea voyage in the North Pacific, near the Aleutian Islands of Alaska, you begin to explore a deep, long, narrow region in the ocean floor. You begin to discuss what this is with a partner and come up with the theories below. Determine whether each of the statements below presents a likely scenario. Select the three that apply. a) It is most likely a deep-ocean trench because they are common along the active continental margins. b) It is most likely a rift valley. c) The feature was most likely caused by one oceanic crust subducting under a leading edge of a continent. d) Even though turbidite deposits are missing, it is most likely a submarine canyon because it runs parallel to the continental margin. e) It is most likely a deep-ocean trench because they are common along the margins of the Pacific Ocean.

e

Passive continental margins are characterized by all the following except: a) shallow coastal waters. b) very little volcanic and earthquake activity. c) broad continental shelves. d) thick sediment accumulation. e) deep-sea trenches.

e

Satellites are used to map the ocean floor because: Satellites are used to map the ocean floor because: a) they can "see" large areas of the seafloor at one time. b) they are unaffected by surface weather. c) they can cover areas where ships have not produced surveys. d) the shape of the ocean surface itself reflects large features on the seafloor below. e) All the above statements are correct.

f

Seamounts form from ancient tablemounts. (t/f)

ring of fire

Subduction zones surrounding the Pacific Ocean give rise to volcanoes. This area surrounding the Pacific Ocean is called the ______

a

The correct order of seafloor features from the coast to the mid-ocean ridge is: a) shelf, slope, rise, abyssal plain. b) abyssal plain, shelf, slope, rise. c) abyssal plain, rise, slope, shelf. d) rise, abyssal plain, slope, shelf. e) slope, rise, shelf, abyssal plain.

c

The direction of motion along a seafloor transform fault is: a) associated with turbidity currents. b) perpendicular to the direction of plate movement. c) in the same direction as the plates are spreading. d) in the same direction as the ridge offset. e) influenced by underwater boundary currents.

b

The instrument that emits a high-frequency sound beam to measure the depth of the ocean developed in the 1950s is the: The instrument that emits a high-frequency sound beam to measure the depth of the ocean developed in the 1950s is the: a) SeaWif. b) precision-depth recorder (PDR). c) SeaMARC. d) Seabeam. e) GLORIA.

a,b,c,d,e

The majority of ocean trenches are associated with ___________. a) volcanic arcs and active continental margins b) the Pacific Ring of Fire c) subduction zones and associated faults d) very deep ocean water depths e) narrow or no continental shelves f) the mid-ocean ridge

bathymetry

The measurement of ocean depth and the charting of seafloor topography is called

d

The method that is used most frequently to investigate sediment and rock layers of the sea floor is: The method that is used most frequently to investigate sediment and rock layers of the sea floor is: a) drilling. b) satellite observation. c) direct observation. d) sound waves (specifically seismic reflecting profiling). e) light waves.

b

What types of deposits do turbidity currents leave in alluvial fans? A) lateral bedding containing mostly fine material mixed with coarse material B) graded bedding that begins as coarse material and becomes finer upward C) lateral bedding containing mostly coarse material mixed with fine material D) graded bedding that begins as fine material and becomes coarser upward

a

What would you look for as evidence that a rock layer formed from materials deposited by ancient turbidity currents? a) repeated sequences of graded bedding that begin as coarse material and become finer upward b) repeated sequences of lateral bedding containing mostly coarse material mixed with fine material c) repeated sequences of graded bedding that begin as fine material and become coarser upward d) repeated sequences of lateral bedding containing mostly fine material mixed with coarse material

a,b,c,f

Which of the following feature(s) is/are associated with the mid-ocean ridge? a) a central rift valley b) hydrothermal vents c) volcanoes d) a trench e) thick layers of sediment f) basalt volcanism and pillow lavas

b

With respect to mid-ocean ridges, transform faults are: a) parallel to the rift valley. b) perpendicular to the ridge axis. c) located in submarine canyons. d) associated with hydrothermal vents.

submarine canyons, turbidity currents

_________ are deep valleys at passive continental boundaries. They are likely carved out by _________ , which occur when sediment-laden water rapidly moves down slope.

atlantic ocean basin

expanding ocean basin

pacific

shrinking ocean basin

d

which does not fit A. turbidity currents B. graded bedding C. turbidite deposits D. abyssal plains E. deep-sea fans

b

which does not fit A. abyssal plain B. continental flood basalt C. continental rise D. continental shelf E. continental slope

c

which does not fit: A. abyssal hill B. abyssal plain C. submarine canyon D. seamount E. tablemount

b

which does not fit: A. black smoker B. deep focus earthquake C. hydrothermal vent D. rift valley E. white smoker

E

which does not fit: A. metal sulfide deposits B. pillow basalts C. rift valley D. seamounts E. trenches