OCE 1001 Ch. 3

Please identify the word and/or phrase that does NOT fit the pattern

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

Please identify the word and/or phrase that does NOT fit the pattern

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

Please identify the word and/or phrase that does NOT fit the pattern

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

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

False

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

False

Seamounts form from ancient tablemounts.

False

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

False

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

False

Turbidity currents are highly erosive and are thought to be responsible for the creation of deep-sea trenches.

False

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

True

What effect do turbidity currents have on the continental slope?

Turbidity currents are erosive to the continental slope and, as a result, carve out submarine canyons.

How do turbidity currents affect canyons?

Turbidity currents erode material from canyons as currents move downslope

continental shelf

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

What common item is used in this video to demonstrate a turbidity current?

a large jar filled with water and sediment

Sediments deposited by the process of suspension settling produce the main sediment found on ___________.

abyssal plains

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

abyssal plains.

ocean trench

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

Passive continental margins are characterized by all the following except:

deep-sea trenches

What are turbidity currents?

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

Oceanic ridges and rises result from seafloor spreading along:

divergent plate boundaries.

Consider a continental margin that has a very broad, flat continental shelf and a slope that descends 1 km to the deep ocean basin. Based on this information, this margin is ___________________.

far from an oceanic ridge

abyssal plain

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

All the following are considered part of the continental margin except the:

fracture zone.

What is the characteristic layering of an individual turbidity current deposit called?

graded bedding

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

graded bedding that begins as coarse material and becomes finer upward

The direction of motion along a seafloor transform fault is:

in the same direction as the plates are spreading.

How often do turbidity currents occur?

infrequently

What process(es) affect the shape and structure of continental shelves?

large fluctuations in sea level erosion of sediment major climate changes, such as ice ages eposition of sediment

multi-beam sonar

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

Transform faults have all of the following characteristics except:

movement occurs in the same direction

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

oceanic rises.

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

oceanic trenches.

Most ocean floor features owe their origins to _________.

plate tectonic processes

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

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

Identify the major feature of a slow-spreading mid-ocean ridge.

rift valley

Measurement of ocean floor bathymetry from satellites relies on ___________.

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

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

seamounts.

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

turbidity currents.

precision-depth recorder (PDR)

uses high frequency sound waves to measure ocean depth

Nearly all oceanic islands are __________.

volcanic in origin

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

4,000-5,000 m below sea leve

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?

5,550 meters

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?

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.

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

True

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

True

Satellite measurements of the ocean surface can be used to make maps of the seafloor.

True

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 __________.

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

he reason the deposit on the bottom forms the way it does is a result of __________.

settling velocity

The two relatively flat areas on the hypsographic curve represent

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

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

sound waves (specifically seismic reflecting profiling).

What is turbidity?

suspended sediment

The majority of ocean trenches are associated with ___________.

the Pacific Ring of Fire narrow or no continental shelves very deep ocean water depths volcanic arcs and active continental margins subduction zones and associated faults