Oceanography Ch. 3

Characteristics of active continental margins include all of the following except __________. (a) broad continental shelf (b) chains of islands (c) deep-sea trenches (d) thin sediment accumulation (e) volcanic and earthquake activity

a. broad continental shelf

The deep-sea bottom is monotonously flat and featureless. (a) True (b) False

a. false

Active continental margins are located __________. (a) along the east coast of the United States (b) along the east coast of South America (c) on the west coasts of both North and South America (d) all around Africa

c. along the west coast of North and South America

A measurement of ocean depth and seafloor topography is __________. (a) hypsometric curve (b) seismic survey (c) bathymetry (d) biology

c. bathymetry

All the mid-ocean ridges are in the center of an ocean basin. (a) True (b) False

a. true

Hydrothermal vents have a significant impact on ocean chemistry. (a) True (b) False

a. true

Sediments of the continental rise can exhibit characteristics similar to those formed by rivers on land. (a) True (b) False

a. true

Seamounts form from ancient tablemounts. (a) True (b) False

b. false

The islands bordering the deep-sea trenches __________. (a) result from a series of quiet, continuous basaltic eruptions (b) are accumulations of sediments on the margins of the trenches (c) are formed from the activities of coral and other organisms (d) are explosive volcanoes that emit andesite lavas

d. are explosive volcanoes that emit andesite lavas

Submarine canyons occur __________. (a) at the part of an ocean basin nearest the poles (b) near the edges of ocean basins associated with continental shelves and slopes (c) at the part of an ocean basin nearest the equator (d) at the center of an ocean basin, at the edges of the mid-ocean ridge (e) on the edges of trenches

b. near the edges of ocean basins associated with continental shelves and slopes

A __________ is used to determine the shape position of boundaries. (a) hypsometric curve (b) seismic survey (c) bathymetry (d) biology

b. seismic survey

The most gradual change in slope in the ocean can be found at the __________. (a) abyssal plain (b) continental rise (c) continental shelf (d) deep ocean trench (e) mid-ocean ridge

a. abyssal plain

Which of the following is not characteristic of the deep sea basins? (a) Canyons (b) Plains (c) Hills (d) Seamounts (e) Guyots

a. canyons

The great heaps of unconsolidated sediment at the base of the continental slope are known as __________. (a) the continental rise (b) the abyssal hills (c) the abyssal plains (d) the mid-ocean mountains (e) the mid-ocean ridge

a. continental rise

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

a. deep sea trenches

A cumulative plot of area versus depth or elevation is __________. (a) hypsometric curve (b) seismic survey (c) bathymetry (d) biology

a. hyposometric curve

The continuous submarine mountain range which winds through all the oceans is called the mid-ocean __________. (a) ridge (b) archipelago (c) plume (d) cordillera (e) divide

a. ridge

Abyssal hills are only visible in the Pacific Ocean because __________. (a) sediment has covered those found in the other ocean basins (b) there are none in the Atlantic and Indian ocean basins (c) they are higher in the Pacific than in the other ocean basins (d) they have been destroyed in active plate margins (e) turbidity currents have eroded abyssal hills in the other ocean basins.

a. sediments have covered those found in the other ocean basins

The flat, drowned edges of the continents are called the continental __________. (a) rises (b) wedges (c) slopes (d) shelves (e) ridges

a. shelves

Which is greater, the average height of the continents or the average depth of the ocean? (a) The average depth of the ocean is greater. (b) The average height of the continents is greater.

a. the average depth of the ocean

A sediment-laden current that flows off of the continental shelf is called a turbidity current. (a) True (b) False

a. true

Abyssal plains are more extensive on the floor of the Atlantic as compared those on the floor of the Pacific. (a) True (b) False

a. true

Subduction zones appear to remain nearly stationary over long periods of time. (a) True (b) False

a. true

Trenches change their position over time. (a) True (b) False

a. true

In general, continental shelves tend to be wider in the __________. (a) Pacific ocean, because its margins tend to be active (b) Atlantic ocean, because its margins tend to be passive (c) Atlantic ocean, because its margins tend to be active (d) Pacific ocean, because its margins tend to be passive

b. Atlantic ocean because its margins tend to be passive

At the base of many continental shelves, the ocean floor flattens out to a broad region formed from materials eroded from the adjoining continental shelf and slope. This plain is termed the __________. (a) abyss (b) abyssal plain (c) continental plain (d) continental rise (e) guyot

b. abyssal plain

Hydrothermal springs seem to be located near __________. (a) passive continental margins (b) active areas of seafloor spreading (c) the edges of the deep sea trenches (d) the margins of the Hawaiian chain (e) on the abyssal plains

b. active areas of seafloor spreading

The mid-ocean mountains, such as the ridges and rises, __________. (a) are similar in origin to the Alps, the Rockies, and the Appalachians (b) are constructed of volcanic basalt (c) are composed of folded and faulted marine sedimentary rocks (d) are similar in size and features to most continental mountains

b. are constructed of volcanic basalt

Continental rises are formed __________. (a) as a result of the slow accumulation of sediments from the water column (b) by many deep sea fans (c) in association with hydrothermal vents (d) next to submarine canyons (e) on the flank of a mid-ocean ridge

b. by many deep sea fans

The transition between the shelf and the deep seafloor is __________. (a) the littoral zone (b) the continental slope and rise (c) the abyssal plain. (d) the mid-ocean ridge (e) the submarine canyon

b. continental slope and rise

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

b. deep sea trenches

Submarine canyons were most likely formed by __________. (a) deposition of terrestrial sediment (b) earthquake activity (c) erosion by major rivers in the past (d) erosion by turbidity currents (e) scouring by glacier during the last ice age

b. earthquake activities

Due to the very harsh environment, few organisms are found in association with hydrothermal vents. (a) True (b) False

b. false

Mid-ocean ridges are rises occupy a small portion of the deep ocean basin, only around 10%. (a) True (b) False

b. false

Most of the future deep-ocean research being planned by oceanographers involves sending human pilots and observers to the greatest ocean depths in vehicles like Alvin, Trieste, and Shinkai-6500, (a) True (b) False

b. false

The deepest portions of the ocean are part of the relatively narrow features called submarine canyons. (a) True (b) False

b. false

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

b. in the same direction as the plates are spreading

The deepest parts of the Pacific Basin are located __________. (a) in the center, surrounding the island of Hawaii. (b) near the margins of South America, Japan, and the Marianas Islands. (c) in the eastern part of the basin, off North America. (d) in the rift valley of the East Pacific Rise

b. near the margins of South America, Japan, and Marianas Islands

Which is greater, the height of the world's tallest mountain or the depth of the world's greatest trench? (a) The height of the world's tallest mountain (Mt. Everest). (b) The depth of the world's greatest trench (Challenger Deep).

b. the depth of the world's greatest trench.

The characteristics of deep trenches indicate __________. (a) they are erosional features similar to the Grand Canyon in Arizona (b) they are elongated subduction-related creases in the oceanic crust (c) they are glacial troughs dating back to the Ice Age (d) they are erosional canyons cut by turbidity currents

b. they are elongated subduction-related creases in the oceanic crust

Bathymetry refers to submarine __________. (a) mineralogy (b) topography (c) biology (d) currents (e) waves

b. topography

Guyots were once active volcanoes whose tops were flattened and leveled by __________. (a) currents (b) wave erosion (c) volcanic explosions (d) solidified lava (e) ice sheets in the last ice age

b. wave erosion

Only about __________ of the Earth's surface projects above sea level. (a) 51% (b) 17% (c) 29% (d) 94% (e) 74%

c. 29%

The average width of the continental shelves is about __________ kilometers (__________ miles). (a) 16 (10) (b) 35 (22) (c) 67 (42) (d) 100 (160) (e) 800 (1,280)

c. 67 (42)

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

c. continental slope

The most rapid change in slope in the ocean is found at the __________. (a) abyssal plain (b) continental slope (c) oceanic trench (d) submarine canyon (e) volcanic seamount

c. oceanic trench

The continental margins are relatively shallow because __________. (a) they have been built up by sediments contributed by marine organisms (b) the underlying crust is lighter (c) they have been built up by sediment washed off of the continents (d) they were formed in the last ice age, when the oceans were shallower (e) sea level has dropped in the last 100 years

c. they have been built up by sediment washed off of the continents

The deepest parts of the oceans are the ___________. (a) rift valleys (b) submarine canyons (c) trenches (d) deep basins (e) fault scarps

c. trenches

An analysis of the sequential breaking of transatlantic telephone and telegraph cables led to a better understanding of __________. (a) the distribution of submarine trenches (b) the composition of sediments (c) turbidity currents (d) hydrothermal vent communities (e) the size of the ocean

c. turbidity currents

The continental shelf __________. (a) is a narrow strip on the East Coast of the United States (b) is a steeply dipping zone dropping off to the deep seafloor (c) is a featureless plain unlike the neighboring continent (d) is a gently sloping platform with a variable landscape (e) all of the above

d. a gently sloping platform with a variable landscape

The landscape of the seafloor would best be described as __________. (a) a featureless plain (b) a smooth descent with the deepest portions farthest from land (c) similar in rock type, sediment thickness, and erosional processes to those found on the land (d) containing ridges, trenches, seamounts, and other features different from those found on land

d. containing ridges, trenches, seamounts, and other features different from those found on land.

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

d. fracture zone

The origin of submarine canyons is not well understood, but most likely __________. (a) is tectonic, and represents down-folds of rock within the continental shelf (b) is organic, resulting from the activities of burrowing organisms (c) is glacial, the work of glaciers depositing rock debris on the shelf (d) is erosional, started by streams during periods of sea level lowering

d. is erosional, started by streams during periods of seal level lowering

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

d. mid ocean ridges

The trailing edge of a moving continental crustal plate is most likely to exhibit features associated with __________. (a) frequent earthquake activity (b) active continental margins (c) widespread volcanism (d) passive continental margins

d. passive continental margins

The correct order of marine provinces from the coast to the mid-ocean ridge is __________. (a) abyssal plain, rise, slope, shelf (b) abyssal plain, shelf, slope, rise (c) rise, abyssal plain, slope, shelf (d) shelf, slope, rise, abyssal plain (e) slope, rise, shelf, abyssal plain

d. shelf, slope. rise. abyssal plain

The two relatively flat areas on the hypsometric curve represent __________. (a) continental mountains and abyssal plains (b) continental mountains and mid-ocean ridges (c) continental slopes and deep-sea trenches (d) some interior continental areas/ coastal plains and abyssal plains (e) some interior continental areas/ coastal plains and mid-ocean ridges

d. some interior continental areas/coastal plains and abyssal plains

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

e. all of the above

Submarine canyons are __________. (a) found worldwide, on all kinds of shelves (b) steep-walled and narrow (c) cut into firm rock (d) cut into the shelf and may extend almost to the shore (e) all of these

e. all of these

A turbidity current is __________. (a) a fast surface current of water that runs parallel to beaches and that causes a rapid decrease in water clarity (b) the cause of mid-ocean maelstroms (whirlpools) (c) a phenomenon associated with violent atmospheric storms at sea (d) something that always occurs at river mouths in shallow water, but does not extend into water more than 50 meters (165 feet) deep (e) none of the above

e. none of the above

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

e. perpendicular to the ridge axis

Extinct volcanoes with conical tops and steep sides in the ocean basins are called __________. (a) islands (b) archipelagos (c) banks (d) atolls (e) seamounts

e. seamounts

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

e. sound waves

Which of the following statements accurately describes continental margins? (a) They are regions of great geological stability. (b) They are characteristic of the margins of the Atlantic Basin. (c) They are areas of frequent earthquakes and volcanoes, where crustal plates are converging or are in collision. (d) They are areas where crustal plates are actively moving apart. (e) They are usually different in topography from the adjoining coast.

e. they are usually different in topography from the adjoining coast

The axis of the mid-ocean ridges is segmented by a series of __________. (a) normal faults (b) reverse faults (c) thrust faults (d) gravity faults (e) transform faults

e. transform faults

Warm-water hydrothermal vents form __________. (a) abyssal hills (b) black smokers (c) cold seeps (d) turbidity currents (e) white smokers

e. white smokers