Deck 4: Ocean Basins

Question 1

The deepest parts of the Pacific Basin are located:

A) in the center of the Pacific Ocean near the Hawaiian Islands.
B) in the eastern part of the basin, off North America.
C) in the rift valley of the East Pacific Rise.
D) near the margins of South America, Japan, and the Marianas Islands.

Answer 1

D

Question 2

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.

Answer 2

A

Question 3

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 composed of folded and faulted marine sedimentary rocks.
C) are constructed of volcanic basalt.
D) are similar in size and features to most continental mountains.

Answer 3

C

Question 4

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.

Question 5

The origin of submarine canyons is not well understood, but most likely

A) is erosional, started by streams during periods when the sea level was lower.
B) is tectonic, and represents down-folds of rock within the continental shelf.
C) is organic, resulting from the activities of burrowing organisms.
D) is glacial, the work of glaciers depositing rock debris on the shelf.

Question 6

The average elevation of the continents is:

A) 8,848 meters (16,000 feet)
B) 840 meters (2,760 feet)
C) 3,800 meters (12,000 feet)
D) 5,000 meters (15,000 feet)

Question 7

The continental shelf:

A) is a narrow strip on the East Coast of the United States.
B) is a steep zone dropping off to the deep seafloor like a cliff.
C) is a featureless plain unlike the neighboring continent.
D) is a gently sloping platform with a variable landscape.

Question 8

Submarine canyons:

A) always run parallel to coasts.
B) have gradual slopes and are very wide.
C) can never cut into rock.
D) cut into the shelf and may extend almost to the shore.

Question 9

Which of the following statements is true regarding the islands bordering deep-sea trenches?

A) They are the result of a series of quiet, continuous basaltic eruptions.
B) They are accumulations of sediments on the margins of the trenches.
C) They are formed from the activities of coral and other organisms.
D) They are explosive volcanoes and are called island arcs.

Question 10

The characteristics of deep trenches indicate:

A) they are submerged erosional features.
B) they are elongated depressions in the oceanic crust.
C) they are glacial troughs dating back to the Ice Age.
D) they are erosional canyons cut by turbidity currents.

Question 11

Hydrothermal vents are located near:

A) passive continental margins.
B) zones of rapid seafloor spreading.
C) the edges of the deep sea trenches.
D) the margins of the Hawaiian chain.

Question 12

The deep-ocean basin includes all of the following features EXCEPT:

A) continental shelf.
B) abyssal hills.
C) abyssal plains.
D) mid-ocean ridges.

Question 13

Water depth over continental shelves averages only about:

A) 16 meters(50 feet)
B) 35 meters(115 feet)
C) 75 meters (250 feet)
D) 100 meters (300 feet)

Question 14

Which of the following statements accurately describes active 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 lithospheric plates are converging or are in collision.
D) They are areas where lithospheric plates are actively moving apart.

Question 15

Submarine canyons occur:

A) at the part of an ocean basin nearest the poles.
B) at the part of an ocean basin nearest the equator.
C) at the junction between continental shelf and continental slope.
D) at the center of an ocean basin, at the edges of the mid-ocean ridge.

Question 16

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.

Question 17

The landscape of the seafloor could 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) huge abyssal plains containing ridges, trenches, seamounts.

Question 18

How can a satellite sense the contours of the ocean bottom from space?

A) By shining a laser through the ocean to see the bottom.
B) By using radar to sense the height of the sea surface over submerged features.
C) By using sonar to measure ocean bottom contours directly.
D) By sensing changes in gravity as it flies over trenches and mountain ranges.

Question 19

The leading 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.

Question 20

Which of the following statements accurately describes a turbidity current?

A) A fast dense current of water that carries sediments offshore.
B) The cause of mid-ocean trenches.
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.

Question 21

Flat-topped seamounts that rise from the ocean floor are called:

A) ridges.
B) island arcs.
C) guyots.
D) abyssal hills.

Question 22

Which of the following statements most accurately describes how the continental rise is formed?

A) From the convergence of oceanic plates at passive continental margins.
B) From volcanic activity at active continental margins.
C) From accumulated sediments at the base of the continental slope.
D) from sedimentation surrounding spreading centers.

Question 23

The deepest part of the ocean is the:

A) Peru-Chile Trench.
B) Mid-Atlantic Ridge.
C) Mariana Trench.
D) Abyssal plains.

Question 24

The Andes mountain range is an example of a(n):

A) ridge system.
B) island arc system.
C) passive margin.
D) active margin convergent zone.

Question 25

The Emperor Sea Mounts are found in:

A) the Sagasso Sea.
B) the South Pacific.
C) the North West Pacific.
D) the coastal region of Australia.

Question 26

An example of a continental rise that is extraordinarily wide is found:

A) in the Red Sea.
B) in the Pacific at the active margin called the "Ring of Fire."
C) in the Bay of Bengal.
D) off the east coast of Florida.

Question 27

A seamount is a volcanic projection that does not rise above the surface.

Question 28

The oldest and best-known deep-diving submarines is the:

A) Geostat
B) Alvin
C) TOPEX/Poseidon
D) Challenger

Question 29

Abyssal hills are small extinct volcanoes commonly associated with:

A) seafloor spreading.
B) convergent zones.
C) active continental margins.
D) continental shelves.

Question 30

Scientists think that turbidity currents contribute to the formation of submarine canyons.

Question 31

The Challenger expedition used multibeam echo sounders to contour the seafloor.

Question 32

Hydrothermal vents such as black smokers are found at spreading centers.

Question 33

Passive continental margins line coasts that are far from tectonically active areas.

Question 34

Trenches and island arcs are found at spreading centers.

Question 35

A guyot is found at spreading centers.

Question 36

The discovery and study of ocean floor contours is called:

A) bathymetry.
B) abyssomethry.
C) stratigraphy.
D) paleoceanography.

Question 37

the widest continental shelf is located in:

A) the Arctic Sea north of Siberia.
B) the western edge of South America.
C) the margin surrounding the Hawaiian Islands.
D) the Emperor Seamounts.

Question 38

Abyssal plains and abyssal hills cover a quarter of the Earth's surface.

Question 39

Continental shelves can be made of either granite crust, basalt crust or both.

Question 40

The shelf break is the transition between the continental slope and the abyssal plains.

Question 41

What is a submarine canyon and how are they formed?

Question 42

What methods do scientists use to determine the bathymetry of the ocean floor?

Question 43

The Mariana Trench is about 20% deeper than Mount Everest is high. Explain how this statistic was determined and describe how each of these features were formed.

Question 44

Abyssal Plains and Abyssal hills cover about 25% of the surface of the earth. How are these features characterized?

Question 45

Distinguish between active and passive continental margins.