Geology Module 9

Where does an accretionary wedge form?

deep-ocean trench

How many seconds would it take an echo sounder's ping to make the trip from a ship to the Challenger Deep (10,994 meters) and back? Recall that depth = 1/2 (1500 m/sec × Echo travel time).

14.66 seconds

Ocean covers approximately ________ percent of Earth's surface

71

Attraction of seawater to submarine features like seamounts and oceanic ridges is due to ________; it results in areas where the surface of the ocean bulges upward by a small amount.

gravity

Manganese nodules are an example of ________ sediment.

hydrogenous

Minerals that crystallize directly from seawater are examples of ________ sediment

hydrogenous

The ocean has a three-part layered structure (surface mixed zone, transitional zone, and deep zone) at all latitudes.

False

The west coast of South America and the east coast of North America display the same kind of continental margin.

False

The ________ Ocean is largest; the ________ Ocean is smallest.

Pacific; Arctic

_______ continental margins typically exhibit wide, extensive, continental shelves.

Passive

An echo sounder operates by measuring the time required for ________.

a sound pulse to travel from a ship to the seafloor and back

Which of the following would NOT be associated with turbidity currents?

formation of seamounts

Which of the four lettered locations in this figure shows a guyot?

C

________ develop where oceanic lithosphere bends downward and sinks into the mantle.

Deep-ocean trenches

Turbidites and siliceous oozes are both biogenous sediments.

False

________ is the proportion of dissolved salts to pure water.

Salinity

Which one of the following statements concerning oceanic ridges is FALSE?

Sediments include thick siliceous ooze deposits and sandy turbidite beds.

How does the average depth of the oceans compare to the average elevation of the continents?

The ocean floors are about four times as deep, on average, than the average elevation of the continents above sea level.

Sand, silt, and clays deposited on the ocean floor are described as terrigenous sediments.

True

________ continental margins occur where oceanic lithosphere is being subducted beneath the edge of a continent.

active

Which of the following is associated with oceanic ridges?

all of the above

Seamounts ________.

are volcanoes that form on the ocean floor

Where is the continental rise?

between an abyssal plain and continental slope

A pile of clam shells is an example of ________ sediment.

biogenous

Which element is the most common dissolved in seawater?

chlorine

Which one of the following is NOT part of the continental margin?

continental trench

No thermocline exists in high-latitude regions because there is little temperature difference between the top and bottom of the water column. In such a situation the water column is said to be ________.

isothermal

The oceanic ridge system is the ________ topographic feature on Earth.

longest

Where would you go to find "black smokers" (deep sea hydrothermal vents)?

oceanic ridge

At low latitudes, the ________ is a zone of rapid temperature change over a relatively short depth. It is associated with a similar depth zone marked by a change in density, called the ________.

thermocline; pycnocline

A prominent feature of the Mid-Atlantic Ridge is a very deep linear valley known as a(n) ________.

rift valley