The Majority Of Ocean Trenches Are Associated With __________.

Which of the following statements accurately describe(s) the depth and height of Earth's surface as shown on the hypsographic curve?

-The percentage of Earth's surface above sea level is 29.2%.
-More people have been to the top of the tallest mountain on Earth than have been to the bottom of the deepest trench
-The average depth of the ocean is much greater than the average height of land.

Why is the average depth of the ocean much greater than the average height of land?

Oceanic crust is more dense than continental crust.

To which planet is NASA sending the spacecraft InSight to study crustal movements similar to earthquakes?

Mars

Which of the following is an example of an active continental margin?

-west coast of the United States
-west coast of Chile

What features are associated with a passive continental margin?

-continental rise
-Flat coastal terrain

Which of the following is a difference between passive and active continental margins?

Convergent active margins will have a steep continental slope, whereas passive margins will have a more gradual slope.

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

a large jar filled with water and sediment

What is turbidity?

suspended sediment

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.

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

settling velocity

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

graded bedding

1. Oceanic crust spreads at mid-ocean ridges, creating new crust and slowly enlarging the ocean basin.

...

2. Submarine canyons are deep valleys at passive continental boundaries. They are likely carved out by turbidity currents, which occur when sediment-laden water rapidly moves down slope.

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3. Melt from the subducting plate rises to the surface, erupts through the crust on the overriding plate and forms continental volcanic arcs on continents, or volcanic island arcs in the ocean.

...

4. Subduction zones surrounding the Pacific Ocean give rise to volcanoes. This area surrounding the Pacific Ocean is called the Ring of Fire.

...

measurement of ocean depth and seafloor topography

Bathymetry

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

Multi-beam sonar

uses high frequency sound waves to measure ocean depth

Precision-depth recorder (PDR)

cumulative plot of the frequency of depth or elevation

Hypsographic curve

used to determine ocean structure beneath the sea floor

Seismic reflection profile

Satellites are used to map the ocean floor because ________.

the shape of the ocean surface reflects large features on the seafloor

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

sound waves (specifically seismic reflecting profiling).

The first recorded attempt to measure the ocean's depth was conducted using which of the following techniques?

Sounding

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

The measurement of ocean depth and the charting of seafloor topography is called __________.

bathymetry

Most large ocean floor features owe their origins to _________.

plate tectonic processes

Of the following techniques, which one(s) can be used to map the sea floor? Choose all that apply.

-sending sound through water (sonar)
-direct visitation of the sea floor
-recording many depths using a long cable
-using satellites to measure the sea surface

Of the following statements about mapping the ocean floor, which is/are true? Choose all that apply.

-Multibeam surveys from ships produce very detailed maps of the sea floor.
- Only about 20% of the sea floor has been accurately mapped in detail.
-Measurements of sea surface elevation by satellites are used to produce maps of the sea floor.

Satellites use microwave beams to measure sea level to an accuracy of four ________.

centimeters

Judge the following sentence according to the criteria given below: Multibeam SONAR systems have resolution limitations in deep water BECAUSE beams of sound spread out with depth.

The assertion and the reason are both correct, and the reason is valid.

Active continental margins are characterized by which of the following?

Deep-sea trenches

The correct order of seafloor features from the coast to the mid-ocean ridge is:

shelf, slope, rise, abyssal plain.

Characteristics of passive continental margins include which of the following?

Broad continental shelves

Which of the following features is related to transform faults along mid-ocean ridges?

Fracture zone

Passive margins are usually produced over geologic time by which of the following?

Continental rifting and continued sea floor spreading

The average slope of the continental shelf is approximately ________.

a tenth of a degree

Where does the deep-ocean basin begin along a passive continental margin?

Continental slope

Which of the following best describes turbidity currents?

Underwater avalanches of muddy water mixed with rocks and other debris

The distinctive type of sedimentary layering that has largest particles on the bottom and smallest particles on the top, with intermediate sized particles in the middle, is called which of the following?

Graded Bedding

Of the following items, which is/are associated with a passive continental margin? Choose all that apply.

- a continental rise
- a wide continental shelf

What processes influence the shape and features of continental shelves? Choose all that apply.

-tectonic activity produced by offshore faults
- trench formation at convergent boundaries
-major climate changes, such as ice ages
- large fluctuations in sea level over geologic time

On a deep-sea voyage in the North Pacific, near the Aleutian Islands of Alaska, you begin to explore a deep, long, narrow region in the ocean floor. You begin to discuss what this is with a partner and come up with the following theories. Determine whether each statement presents a likely scenario.

-It is most likely a deep-ocean trench because they are common along the active continental margins.
-The feature was most likely caused by one oceanic crust subducting under a leading edge of a continent.
-It is most likely a deep-ocean trench because they are common along the margins of the Pacific Ocean.

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.

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

abyssal plains.

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

seamounts

Volcanic features on the ocean floor that are less than 1,000 meters (0.6 miles) tall are called:

abyssal hills or seaknolls.

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

oceanic trenches.

Older lithosphere is destroyed in association with:

deep-sea trenches.

The island of Java is an example of a volcanic island associated with volcanic activity at a ________.

island arc

Which of the following is the predominant process that forms the thick blanket of sediment on abyssal plains the deep-ocean floor?

Suspension settling

The majority of ocean trenches are associated with ___________. Choose all that apply.

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

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

Judge the following sentence according to the criteria given below: Few abyssal plains are located in the Pacific Ocean BECAUSE turbidity currents only occur along passive continental margins.

The assertion is correct, but the reason is incorrect.

Tamu Massif, the largest single volcano on Earth occurs in which of the following oceans?

Pacific Ocean

Judge the following sentence according to the criteria given below: The Pacific Ring of Fire is home to the majority of Earth's active volcanoes and large earthquakes BECAUSE of the prevalence of divergent plate boundaries along the Pacific Rim.

The assertion is correct, but the reason is incorrect.

Volcanic peaks that are below sea level but rise more than 1 kilometer above the deep-ocean floor and have a flattened top are called ________.

guyots

Seamounts and abyssal hills are ________ in origin.

volcanic

New lithosphere is produced in association with:

oceanic ridges.

Warm water (From 30°C to 350°C) hydrothermal vents form:

white smokers

Warm water (From 30°C to 350°C) hydrothermal vents form:

in the same direction as the plates are spreading.

With respect to mid-ocean ridges, transform faults are:

perpendicular to the ridge axis.

What is a linear sea floor feature that is seismically inactive, occurs beyond offset mid-ocean ridge segments, and the relative movement between two points on either side of the feature is in the same direction?

Fracture zone

What percent of Earth's volcanic activity, each year, takes place on the seafloor?

85%

Which of the following feature(s) is/are associated with the mid-ocean ridge? Choose all that apply.

-central rift valley
-hydrothermal vents
-basalt volcanism and pillow lavas
-volcanoes

Of the following statements about Earth's hypsographic curve, which is/are true? Choose all that apply.

-The hypsographic curve shows the percentage of Earth's surface area that is covered by ocean waters.
-The hypsographic curve shows that a majority of the exposed land is below 1 kilometer in elevation.
-The hypsographic curve shows that a majority of the ocean floor is more than 4 kilometers deep.
- The hypsographic curve shows that the average depth of the ocean is about four times the average height of the continents.

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

4,000 - 5,000 m below sea level

All true oceanic islands are ________ in origin.

volcanic

Which part of Earth's cumulative hypsographic curve includes the mid-ocean ridges?

The shallowest slope below sea level