Exam 2 Chapter 10 – Flashcards
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How is ocean depth calculated by sonar?
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Ocean depth is calculated by the time it takes sound waves to travel from the ship to the seafloor and back to the ship again.
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What type of ocean exploration technique is the best for determining potential oil and gas reservoirs?
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seismic reflection survey
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Name all of the ocean bottom features shown in the image of the Los Angeles coast produced by the multibeam sonar.
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shelf, canyons, slope, rise
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Satellites record slight variations on the sea surface using radar. What do these slight variations represent?
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features on the seafloor
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Which of the following describes a seismic reflection survey?
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Seismic signals produced from an explosion travel to the ocean floor, penetrate some layers, and reflect back to a receiver.
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Which of the following correctly describes the Atlantic and Pacific continental margins?
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The Atlantic is a passive margin, and the Pacific is an active margin.
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Choose the true statement regarding the continental shelf.
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The shelf represents the flooded portions of continents.
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Turbidity currents travel from the shelf through __________, creating deep sea fans.
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canyons
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If the subduction angle is steep, the overriding plate may undergo __________.
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subduction erosion
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Which of the following is true regarding shallow subduction angles?
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Sediment and seamounts are scraped from the downgoing plate to produce an accretionary wedge.
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Name the correct order of rifting events.
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crustal upwarp, rift valley, linear sea, ocean
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The Gulf of Aden represents which part of the rifting sequence?
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linear sea
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The timing of __________ and continental breakup strongly correlate.
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flood basalt formation
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What feature connects the South American Paraná and African Entedeka flood basalts?
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seamount chains
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What sequence of rocks would you expect rift valley evolution to produce, from oldest to youngest?
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volcanic rocks, clastic sedimentary rocks, deep sea sedimentary rocks
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Which is not one of the three broad zones describing the ocean floor?
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continental slope
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Which feature would you expect to find at the mouth of a submarine canyon?
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a deep sea fan
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Which coast represents an active continental margin?
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the west coast of South America
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Moving off the east coast of North America, identify the sequence of environments you would encounter as you move deeper into the Atlantic Ocean.
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continental shelf, continental slope, continental rise, abyssal plain
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Which statement best explains the formation of seamounts?
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They represent volcanoes situated over mantle plumes that have since moved away from their source of magma and subsided.
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Which response best explains the absence of volcanoes and earthquakes at a passive continental margin?
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Earthquakes and volcanoes are rare due to the distance from any active boundaries.
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Which of the following is a true statement regarding the Farallon Plate?
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It was an oceanic plate that used to exist between the Pacific and North American Plates.
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The plate boundary in the U.S. Pacific Northwest is _____, while most of the California coast is characterized by a _____ plate boundary.
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convergent; transform
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Which statement regarding Baja Mexico and the city of Los Angeles is correct?
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Both are located on the Pacific Plate.
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Strike-slip faulting of the Queen Charlotte and San Andreas fault systems shows __________.
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a right lateral sense of motion
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What happened to the Farallon Plate approximately 20 million years ago?
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The San Andreas and Queen Charlotte Faults were established where it was subducted beneath the North American plate.
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What is a seamount?
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An active volcano that occurs along the crest of the mid-ocean ridge.
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What is a tablemount?
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A seamount that grew above sea level, experienced wave erosion, and is now inactive.
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Where do coral reefs exist with sea mounts?
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In tropical latitudes
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Which of the following statements about coral reefs and seamounts is most accurate?
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Coral reefs at the ocean surface grow away from seamounts over time.
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Why do coral reefs at the ocean surface grow away from seamounts over time?
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Seamounts subside as tectonic plates move. Coral reefs grow away from the seamount in order to stay near the sunlight.
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What is the difference between a barrier reef and an atoll?
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Barrier reefs surround an inactive volcano emerging above sea level, while atolls surround the previous location of a submerged volcano.
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Which is the correct order of coral reef development near seamounts?
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Fringing reef, barrier reef, atoll
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How are oceanic ridges different from mountainous regions on the continents? Choose all that apply.
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Ocean ridges form from upwelling mantle rock at divergent boundaries.
