Deck 3: The Sea Floor and Its Sediments

Question 1

Large boulders and cobbles scattered over the deep-sea floor at high-temperate latitudes were most likely deposited by turbidity currents.

Answer 1

False

Question 2

Abyssal hills are single, rounded domes extending at least 3 km above the deep-sea floor.

Answer 2

False

Question 3

The vertical relief across the mountains of the western United States is similar to the vertical relief across the Mid-Atlantic Ridge.

Answer 3

True

Question 4

Oil and gas represent only 50% of the mineral value presently taken from the seafloor.

Question 5

Hydrogenous sediments of the deep-ocean floor predominate in regions where other sediment sources are reduced.

Question 6

Flat-topped seamounts called guyots are formed when volcanic islands subside and are eroded over time.

Question 7

Calcareous sediments of the North Atlantic occur at deeper depths than calcareous sediments in the North Pacific.

Question 8

Manganese nodules are composed entirely of manganese.

Question 9

Calcareous deposits are most likely to be found in more acidic seawater undersaturated in calcite.

Question 10

The smaller the footprint of a sound beam, the greater the detail of the seafloor features.

Question 11

Red mud or brown clay deposits are found under oceanic regions of high biological productivity.

Question 12

The distinctive layering found in marine sediments indicates that the properties of the sediment and the rates of sedimentation have varied with time.

Question 13

Particles of a well-sorted sediment sample fall within a limited size range.

Question 14

Large particles sink faster than small particles of the same density.

Question 15

Calcareous oozes of the open ocean are associated with mid-ocean ridge and rise systems rather than the deep-ocean basin floor.

Question 16

Geologic dredges are used to quantitatively sample the seafloor.

Question 17

Siliceous oozes are found at all ocean depths because of the slow dissolving rate of silica.

Question 18

Submarine canyons are features associated principally with the continental slope; some are associated with past or present rivers.

Question 19

Satellite radar altimeters measure sea surface topography.

Question 20

In the deep sea, biogenous sediments make up the majority of the pelagic deposits.

Question 21

Surface coral formations growing around completely submerged seamounts are called ________.

A) atolls
B) fringing reefs
C) edge reefs
D) conical reefs
E) barrier reefs

Question 22

Lithogenous sediment is ________.

A) derived from rock
B) derived from plants and animals
C) always found at depths over 4500 m
D) always associated with deep-sea trenches
E) derived from the chemistry of the water

Question 23

The deep ocean basins or areas with depth between 4000 m and 6000 m cover more of the Earth's surface than the continents.

Question 24

A fathom is a unit of ________.

A) distance
B) depth
C) speed
D) weight
E) time

Question 25

The continental rise is a product of ________.

A) volcanic activity
B) sedimentation
C) seismic upheaval
D) All of these are correct.
E) None of these is correct.

Question 26

Pelagic sediments are commonly more fine-grained than neritic sediments.

Question 27

What minimum percent must be exceeded for a deep-sea biogenic ooze to be named after its principal component?

A) 75
B) 50
C) 30
D) 20
E) 10

Question 28

Passive continental margins are commonly associated with volcanic and earthquake activity.

Question 29

The floor of a major ocean basin is called a(n) ________.

A) ocean valley floor
B) abyssal plain
C) mid-ocean flat
D) seamount province
E) ridge depression

Question 30

The deepest depth of the oceans is located in which trench?

A) Japan-Kuril
B) Aleutian
C) Peru-Chile
D) Puerto Rico-Cayman
E) Mariana

Question 31

Inactive volcanic seamounts on top of the oceanic crust will

A) continue to elevate with time.
B) subside with time.
C) remain in equilibrium once formed.
D) keep a constant elevation.
E) steepen in slope.

Question 32

Flat-topped, submerged seamounts are referred to as ________.

A) mesas
B) abyssal hills
C) atolls
D) guyots
E) flattops

Question 33

The seafloor tends to be more flat and featureless than the continental areas.

Question 34

The continental shelf on the east coast of the United States. is generally wider than the continental shelf on the west coast of the U.S.

Question 35

Major deposits of silicous oozes from the radiolaria are found centered on which latitudes?

A) 5°N
B) 20°N and S
C) 30°N and S
D) 45°N and S
E) 65°N and S

Question 36

Sediment accumulation in the deep ocean tends to be greater than near the continental margins.

Question 37

Turbidity currents produce some ________.

A) trenches
B) abyssal hills
C) submarine canyons
D) All of these are correct.
E) None of these is correct.

Question 38

Calcareous oozes are more common in deep water than shallow water.

Question 39

Manganese nodules are ________.

A) pelagic ooze
B) volcanic
C) lithogenous sediment
D) pelagic biogenous sediment
E) pelagic hydrogenous sediment

Question 40

Continental shelves are geologically part of the continental crust.

Question 41

Which of the following is least likely to be a major component of marine sediments?

A) Silicous ooze
B) Calcareous ooze
C) Cosmogenous materials
D) Hydrogenous sediments
E) Lithogenous sediments

Question 42

Which type of sediment is the greatest contributor, on a world scale, to the sediments of the neritic zone?

A) Biogenous
B) Terrigenous
C) Hydrogenous
D) Cosmogenous
E) Volcanic

Question 43

Side scan sonar images are the product of the ________.

A) reflectivity of the material
B) depth of the water
C) angle at which the sound strikes the object
D) reflectivity of the material and depth of the water
E) reflectivity of the material, depth of the water, and angle at which the sound strikes the object

Question 44

Sediments found on the seafloor and attributed to processes no longer in existence are called ________.

A) nonexisting sediments
B) pelagic sediments
C) relict sediments
D) rafted sediments
E) sorted sediments

Question 45

Why do small particles descend to the seafloor at rates exceeding expectation?

A) The particles attract each other.
B) The particles increase their density.
C) The particles are incorporated into the fecal pellets of small animals.
D) The particles attract each other and the particles are incorporated into the fecal pellets of small animals.
E) The particles attract each other, the particles increase their density, and the particles are incorporated into the fecal pellets of small animals.

Question 46

The seabed is presently being mined in the United States for ________.

A) phosphorite
B) manganese nodules
C) sand and gravel
D) All of these are correct.
E) None of these is correct.

Question 47

The sediments of the central deep-ocean basins of the North Pacific are formed chiefly from ________.

A) radiolaria
B) foraminafera
C) red clay particles
D) diatoms
E) coral reefs

Question 48

Seventy-five percent of all marine sediments are ________.

A) terrigenous
B) neritic
C) pelagic
D) suspended in the water column
E) produced by active seamounts

Question 49

A sediment deposit close to the continental rise having a coarse material overlaid by successively finer materials of nonmarine origin is called a ________.

A) pelagic deposit
B) rafted deposit
C) hydrogenic deposit
D) turbidite
E) well-sorted deposit

Question 50

Red clay obtains its characteristic color from ________.

A) the remains of bottom organisms
B) the oxidation of iron
C) the silica liberated from diatoms
D) calcium carbonate
E) bacteria of the deep sea

Question 51

Which of the following is NOT true about passive continental margins?

A) They have little seismic or volcanic activity.
B) They form after continents are rifted apart.
C) They tend to be wider than active margins.
D) They occur away from plate boundaries.
E) They are commonly found at subduction zones.

Question 52

Lithification of sediments produces ________.

A) coral
B) turbidites
C) mud flows
D) rock
E) red clay

Question 53

Turbidites are ________.

A) graded sequence of sediments
B) found in submarine canyons
C) characterized by coarse sediments on top of fine sediments
D) graded sequence of sediments and found in submarine canyons
E) found in submarine canyons and characterized by coarse sediments on top of fine sediments

Question 54

Acoustic profiling is used to study ________.

A) sediment size
B) sediment distribution
C) seafloor structure
D) sediment size and sediment distribution
E) sediment distribution and seafloor structure

Question 55

Diatomaceous sediments are

A) oozes.
B) found below 4500 m.
C) found in cold water.
D) All of these are correct.
E) None of these is correct.

Question 56

Close to shore on the continental shelf at high-temperate latitudes, ________ deposits are most likely to predominate.

A) cosmogenous
B) hydrogenous
C) pelagic
D) neritic
E) terrigenous

Question 57

Manganese nodule mining has not developed because of ________.

A) low international market prices in metal
B) unresolved legal ownership problems
C) technical and developmental costs
D) All of these are correct.
E) None of these is correct.

Question 58

The particle size of terrigenous sediments generally ________ with distance from shore.

A) increases
B) decreases
C) stays the same
D) becomes less uniform
E) is less graded

Question 59

Submarine canyons are associated with ________.

A) river systems
B) turbidity currents
C) volcanic eruptions
D) river systems and turbidity currents
E) turbidity currents and volcanic eruptions

Question 60

The silica rich oozes of the Pacific Ocean are due to ________ at high latitudes and ________ at low latitudes.

A) radiolarians; diatoms
B) diatoms; diatoms
C) diatoms; radiolarians
D) radiolarians; radiolarians
E) None of these are correct.

Question 61

Which of the following is most likely a major component of open-ocean sediments along the Equator?

A) Siliceous ooze
B) Calcareous ooze
C) Cosmogenous materials
D) Hydrogenous sediments
E) Lithogenous sediments

Question 62

The east coast of South America ________.

A) is a passive continental margin
B) has a relatively wide continental shelf
C) is an active continental margin
D) is marked by a deep ocean trench
E) is a passive continental margin and has a relatively wide continental shelf

Question 63

Barrier reefs can develop into atolls as the seafloor sinks with age.

Question 64

Gas hydrates are rich in ________.

A) ethanol
B) diesel
C) propane
D) carbon dioxide
E) methane

Question 65

Which of the following is NOT an example of a hydrogenous sediment?

A) Manganese nodules
B) Phosphorites
C) Salts
D) Ooliths
E) Tektites

Question 66

The first scientific voyage to use an echo sounder on a large scale was the ________.

A) Meteor expedition
B) Beagle expedition
C) Fram expedition
D) Discovery expedition
E) Endeavor expedition

Question 67

In general, coarse sediments are found closer to shore and fine sediments are found further offshore.

Question 68

Guyots are flat-topped islands.

Question 69

The deepest parts of the oceans are associated with all of the following except ________.

A) abyssal plains
B) subduction zones
C) trenches
D) sedimentary environments
E) active margins

Question 70

Continental margins consist of the following in increasing distance from the shore.

A) shelf, break, slope, rise
B) rise, break, slope, shelf
C) rise, slope, shelf, break
D) rise, shelf, break, slope
E) rise, shelf, slope, break

Question 71

Turbidity currents are often triggered by earthquakes along passive continental margins.

Question 72

Which of the following is most likely a major component of marine sediments near the continents?

A) Siliceous ooze
B) Calcareous ooze
C) Cosmogenous materials
D) Hydrogenous sediments
E) Lithogenous sediments

Question 73

The most common topographic features on Earth are probably ________.

A) rivers
B) beaches
C) abyssal hills
D) continental shelves
E) island arcs.

Question 74

The predominant modern-day method in determining the depth and nature of the seafloor uses ________.

A) heat
B) pressure
C) sound
D) diving
E) optics

Question 75

The deep-sea floor, between 4000 and 6000 m depth, covers more of Earth's surface than the continents.

Question 76

Calcareous sediments are well-preserved in cold, deep water below the CCD.

Question 77

One fathom is equal to ________.

A) 6 meters
B) 1 meter
C) 6 feet (which is roughly 2 meters)

Question 78

In general, sedimentation rates decrease further offshore.

Question 79

Which of the following is most likely a major component of open-ocean sediments at depths shallower than the CCD?

A) Siliceous ooze
B) Calcareous ooze
C) Cosmogenous materials
D) Hydrogenous sediments
E) Lithogenous sediments

Question 80

The ________ of phytoplankton and zooplankton contribute to marine sediments.

A) fecal pellets
B) tests
C) limbs
D) fecal pellets and tests
E) tests and limbs