OCE ch.3
What percent of volcanic activity takes place on the sea floor? 85 75 60
85
How many volcanic peaks are known to exist on the Pacific sea floor? -10,000 to 15,000 -15,000 to 20,000 -> 20,000
> 20,000
The mid-ocean ridge is entirely volcanic and is composed of ________ lavas characteristic of the oceanic crust. granitic basaltic andesitic rhyolitic
basaltic
The measurement of ocean depth and the charting of sea-floor topography is called __________. hydrology bathymetry tomography
bathymetry
The method that is used most frequently to investigate sediment and rock layers of the sea floor is: -sound waves (specifically seismic reflecting profiling). -direct observation. -satellite observation. -light waves.
sound waves (specifically seismic reflecting profiling).
The distance of 1 fathom was standardized to equal exactly ________ feet. 5 7 3 6
6
Active continental margins are characterized by which of the following? Sparse earthquake activity Shallow coastal waters Deep-sea trenches
Deep-sea trenches
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 1500 m/second, what is the water depth in meters? -5550 meters -3000 meters -11,100 meters -7400 meters
5550 meters
Which of the following is the deepest part of the ocean? Abyssal plain Shelf Slope Rise
Abyssal plain
The speed of sound in seawater varies with ________. salinity temperature pressure All of the answers
All of the answers
What kind of hydrothermal vent has the highest temperature and mineral content? -White smoker -Geothermal heat pump -Warm-water vents -Hot springs -Black smoker
Black smoker
Characteristics of passive continental margins include which of the following? -Broad continental shelves -Chains of islands -Thin sediment accumulation
Broad continental shelves
Passive margins are usually produced over geologic time by which of the following? -Subduction of oceanic crust and submarine volcanic activity -Hot spot volcanism forming a chain of islands and seamounts -Continental rifting and continued sea floor spreading
Continental rifting and continued sea floor spreading
Where does the deep-ocean basin begin along a passive continental margin? Continental shelf Shoreline Continental slope Abyssal plain Continental rise
Continental slope
Which of the following features is related to transform faults along mid-ocean ridges? Fracture zone Continental shelf Continental rise Continental slope
Fracture zone
The first systematic bathymetric measurement of the oceans were made in 1872 about the ________. -Comet -HMS Challenger -Odyssey
HMS Challenger
Which gas is being emitted from hydrothermal vents? Oxygen Hydrogen sulfide Hydrogen sulfate
Hydrogen sulfide
Which one of the following is not considered a true type of oceanic island? -Islands that are parts of continents (such as British Isles) -Islands associated with volcanic activity along the mid-ocean ridge (such as Ascension Island along the Mid-Atlantic Ridge) -Islands associated with hotspots (such as Hawaiian islands) -Islands that are island arcs and associated with convergent plant boundaries (such as Japanese archipelago).
Islands that are parts of continents (such as British Isles)
Which of the following is the deepest trench? Middle America Kuril Mariana
Mariana
A continental margin, like the one shown in the image, contains which of the following? -Submarine canyons -Submarine fans -Off-shore faults
Off-shore faults
The majority of ocean trenches are along the margins of which ocean? Atlantic Southern Pacific Indian
Pacific
Deep-ocean trenches and volcanic arcs result from the collision of two plates at convergent plate boundaries and mostly occur along the margins of which of the following oceans? -Pacific Ocean -Southern Ocean -Atlantic Ocean -Arctic Ocean
Pacific Ocean
Tamu Massif, the largest single volcano on Earth occurs in which of the following oceans? -Indian Ocean -Southern Ocean -Arctic Ocean -Pacific Ocean
Pacific Ocean
Identify the major feature of a slow-spreading mid-ocean ridge. Trench Rift valley Volcanic arc
Rift valley
Which of the following techniques used to determine ocean bathymetry is illustrated in the image? -Seismic Reflection -Side-scan Sonar
Seismic Reflection
Which of the following continental margin features is illustrated in the image? -Rift valleys -Deep-ocean trenches -Submarine fans -Off-shore faults -Submarine canyons
Submarine canyons
The average slope of the continental shelf is approximately ________. one-half to one degree two to five degrees greater than five degrees a tenth of a degree
a tenth of a degree
Volcanic features on the ocean floor that are less than 1,000 meters (0.6 miles) tall are called: -abyssal hills or seaknolls. -seamounts. -tablemounts.
abyssal hills or seaknolls.
Directly seaward of the continental shelf is a more steeply sloping region called the: -abyssal plain. -trench. -continental rise. -mid-ocean ridge. -continental slope.
continental slope.
A tablemount is another name for a(n) ________. -abyssal hill -island -nematath -guyot
guyot
The direction of motion along a seafloor transform fault is: in the same direction as the ridge offset. in the same direction as the plates are spreading. associated with turbidity currents.
in the same direction as the plates are spreading.
Graded bedding provides evidence that __________. -submarine canyons were cut by streams during ice ages when the continental shelves were above sea level -turbidity currents carry large particles farther than smaller, lighter particles -large, heavy particles settle out first as current velocity decreases
large, heavy particles settle out first as current velocity decreases
New lithosphere is produced in association with: -oceanic ridges. -deep-sea trenches. -transform faults.
oceanic ridges.
Segments of the oceanic ridge system that are gentler and less rugged in slope due to faster rates of seafloor spreading are called: -deep-sea trenches. -convergent plate boundaries. -transform faults. -fracture zones. -oceanic rises.
oceanic rises.
Abyssal plains are large, flat features that cover about ________ of the planet. -one-quarter -one-third -one-half -one-fifth
one-third
Most large ocean floor features owe their origins to _________. plate tectonic processes ocean currents biological activity erosion and weathering
plate tectonic processes
The instrument that emits a high-frequency sound beam to measure the depth of the ocean developed in the 1950s is the ________. precision-depth recorder (PDR) Seabeam SeaMARC
precision-depth recorder (PDR)
Measurement of ocean floor bathymetry from satellites relies on ___________. Select only one answer. -sea surface elevation, which varies depending on the shape of the underlying sea floor -calculations of how much water versus rock there is at any ocean location -water temperature, which is higher in areas of shallow ocean waters and can easily be detected by satellites
sea surface elevation, which varies depending on the shape of the underlying sea floor
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 __________. - turbidity currents are rare in the Pacific, so little sediment is carried down the continental slopes - the Pacific Ocean is too large for those features to form - sediment is trapped within the trenches of the convergent plate boundaries ringing the Pacific
sediment is trapped within the trenches of the convergent plate boundaries ringing the Pacific
Relatively few abyssal plains are located in the Pacific Ocean due to: -the presence of convergent active margins. -its smaller size compared to other ocean basins. -the absence of convergent active margins. -the presence of seamounts.
the presence of convergent active margins.
Seamounts and abyssal hills are ________ in origin. -volcanic -metamorphic -sedimentary -seismic
volcanic
Nearly all oceanic islands are __________. (Choose the best answer.) -volcanic in origin -formed at high-standing areas of mid-ocean ridges -formed at hotspots as lithospheric plates pass over mantle plumes -parts of continents separated from continents -parts of volcanic island arcs
volcanic in origin
Warm water (From 30°C to 350°C) hydrothermal vents form: -black smokers -turbidity currents -white smokers -abyssal hills.
white smokers