Oceanography Test 1- Chapter 3

True

Satellites measurements of the ocean surface can be used to make maps of the seafloor. True or False?

False

Seamounts form from ancient tablemounts. True or False

abyssal plains

Sediments deposited by the process of suspension settling produce the main sediment found on ___________. Select only one answer.

True

Sediments of the continental rise can exhibit characteristics similar to those formed by rivers on land. True or False?

oceanic rises.

Segments of the oceanic ridge system that are gentler and less rugged in slope due to faster rates of seafloor spreading are called:

Turbidity currents erode material from canyons as currents move downslope.

How do turbidity currents affect canyons?

infrequently

How often do turbidity currents occur?

sediment is trapped within the trenches of the convergent plate boundaries ringing the Pacific

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 __________.

sea surface elevation, which varies depending on the shape of the underlying sea floor

Measurement of ocean floor bathymetry from satellites relies on ___________. Select only one answer.

plate tectonic processes

Most ocean floor features owe their origins to _________.

volcanic in origin

Nearly all oceanic islands are __________.

False

Ocean trenches are deep linear scars in the ocean floor caused by the divergence of plates along divergent plate boundaries. True or False

divergent plate boundaries.

Oceanic ridges and rises result from seafloor spreading along:

true

Oceanic ridges are cut by a number of transform faults, which offset spreading zones.True or False

deep-sea trenches.

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

False

The three major provinces of the ocean floor are continental margins, deep-ocean basins, and submarine canyons. True or False?

some interior continental areas/coastal plains and abyssal plains on the ocean floor.

The two relatively flat areas on the hypsographic curve represent:

movement occurs in the same direction.

Transform faults have all of the following characteristics except:

ocean trench

deep linear scars on the deep-ocean floor caused by plate convergence

abyssal plain

flat depositional surfaces that cover extensive portions of the deep-ocean basins

deposition by waves

formation of continental shelves

sound waves (specifically seismic reflecting profiling).

he method that used most frequently to investigate sediment and rock layers of the sea floor is:

5,550 meters

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?

C. submarine canyon

A. abyssal hill B. abyssal plain C. submarine canyon D. seamount E. tablemount

B. deep focus earthquake

A. black smoker B. deep focus earthquake C. hydrothermal vent D. rift valley E. white smoker

E. rift valley

A. continental margin B. active margin C. convergent active margin D. transform active margin E. rift valley

D. seaknoll

A. rift valley B. oceanic ridge C. oceanic rise D. seaknoll E. seafloor spreading

D. abyssal plains

A. turbidity currents B. graded bedding C. turbidite deposits D. abyssal plains E. deep-sea fans

fracture zone.

All of the following are considered part of the continental margin except the: continental shelf. fracture zone. continental rise. continental slope. submarine canyon.

oceanic trenches.

Along the margins of the Pacific are found most of Earth's:

True

Black smokers are hydrothermal vents that discharge superheated water with high concentrations of metal sulfides. True or False

The mid-ocean ridge is a topographically high feature, composed of basaltic lavas. Along the crest is a rift valley created by seafloor spreading. Cracks and faults are commonly observed in the central rift valley. Ocean ridges are segments of the mid-ocean ridge with a prominent rift valley and steep, rugged slopes resulting from slower plate divergence. Oceanic rises have slopes that are gentler and less rugged due to faster plate divergence.

Describe characteristics and features of the mid-ocean ridge, including the difference between oceanic ridges and oceanic rises.

A transform fault is a seismically active area that shows evidence of past transform fault activity. Two lithospheric plates are moving in opposite directions in a transform fault. A fracture zone, on the other hand, is a seismically inactive area that offsets the axis of a mid-ocean ridge. There is no relative motion because the lithospheric plates are moving in the same direction.

Describe differences between transform faults and fracture zones.

An echo sounder sends a sound signal from a ship downward into the ocean, where it produces echoes when it bounces off any density difference (e.g., the seafloor). The time it takes for the echoes to return to the point of origination is then used to determine the depth and corresponding shape of the ocean floor.

Describe how an echo sounder works.

False

Due to the very harsh environmental conditions, very few types of organisms are found in association with hydrothermal vents. True or False

Graded bedding is created by turbidity currents. As the current slows, the larger suspended pieces of sediment fall out first, and then progressively smaller pieces settle out.

Explain what graded bedding is and how it forms.

abyssal plains.

Extending from the base of the continental rises into the deep-ocean basins are flat depositional surfaces called:

False

The continental shelf is generally defined as a steeply sloping zone extending from the shoreline to the shelf break. True or False?

False

The deepest portions of the ocean are part of the relatively narrow features called submarine canyons. True or False?

in the same direction as the plates are spreading.

The direction of motion along a seafloor transform fault is:

4,000-5,000 m below sea level

The greatest proportion of Earth's surface lies in this elevation/depth interval.

very deep ocean water depths

The majority of ocean trenches are associated with ___________.

turbidity currents.

Underwater avalanches of muddy water mixed with rocks and debris are:

seamounts

Volcanic peaks on the deep-ocean floor with conical tops are called:

dense mixtures of sand, mud, and other debris that move at high speeds down submarine canyons

What are turbidity currents?

Hydrothermal vents are home to unusual deep-ocean ecosystems that include giant tubeworms, large clams, beds of mussels, and many other creatures. These organisms are able to survive in the absence of sunlight because the vents discharge hydrogen sulfide gas, which is metabolized by Archaea (bacteria adapted to harsh conditions) to provide a food source for other organisms.

What kinds of unusual life can be found associated with hydrothermal vents? How do these organisms survive?

graded bedding that begins as coarse material and becomes finer upward

What types of deposits do turbidity currents leave in alluvial fans?

repeated sequences of graded bedding that begin as coarse material and become finer upward

What would you look for as evidence that a rock layer formed from materials deposited by ancient turbidity currents?

continental shelf

a generally flat zone extending from the shore to the shelf break

multi-beam sonar

a method of mapping the topography of the ocean floor along a strip up to 60 km

precision-depth recorder (PDR)

uses high frequency sound waves to measure ocean depth