ES-1000. Chapter 15 – Flashcards
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Basalt
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Oceanic crust is mostly composed of____.
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Rock Dredge
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A/an __________ __________ is an open-mouthed steel net dragged along the sea floor behind a research ship.
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Seismic Profiler
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The __________ __________ emits a high-energy signal from a research ship that penetrates and reflects from layers in sediment and rock.
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Microwave Radar
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Modern sea-floor maps are made with __________ __________ instruments.
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Rift Valley
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A/an __________ __________ is a deep trough in the crest of many mid-ocean ridges.
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Pelagic Sediment
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__________ __________ is a mixture of clay carried from continents and the remains of tiny plants and animals that live in the surface waters of the oceans.
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Abyssal Plains
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Beyond the Mid-Oceanic Ridge system are flat, level, featureless submarine surfaces called __________ __________.
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Passive Continental Margins
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Continental margins on both sides of the Atlantic Ocean are __________ __________ __________.
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Continental Shelf
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A/an __________ __________ is a shallow, gently sloping submarine surface on the submerged edge of a continent.
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Submarine Canyons
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Deep, V-shaped, steep-walled valleys called __________ __________ are eroded into continental shelves and slopes.
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Guyot
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A flat-topped seamount is called a __________.
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Island Arc
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A chain of volcanic islands that form along a subduction zone is called a/an __________ __________.
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Atoll
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A circular coral reef that forms a ring of island around a central lagoon is a/an __________.
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Seamount
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A/an __________ is a submarine mountain that rises 1 kilometer or more above the surrounding sea floor.
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Accreted Terranes
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California, Oregon, Washington, and western British Columbia were added to North America as __________ __________.
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71
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Oceans cover about __________ percent of the Earth's surface.
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Denser, Sinks
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Oceanic crust is __________ than continental crust and therefore __________ isostatically.
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4-7 km, 20-40 km
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The average thickness of oceanic crust is about __________, whereas the average thickness of continental crust is about __________.
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5
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The depth of the central parts of the ocean basins is about __________ kilometers.
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Hot, Low
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The Mid-Oceanic Ridge rises high above the surrounding sea floor because new lithosphere forming at the ridge axis is __________ and of relatively __________ density.
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Gabbro
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Most of layer 3 of the oceanic crust is composed of __________.
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Normal, Shallow
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Rift valleys are characterized by __________ faults and __________ earthquakes.
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Terrigenous Sediment
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Sand, silt, and clay that erodes from the continents and is carried to the deep sea floor is called __________.
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Abyssal Plains
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The flattest surfaces on Earth are __________.
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Seamount
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A/an __________ is a submarine mountain that rises 1 kilometer or more above the surrounding sea floor.
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Atoll
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A circular coral reef that forms a ring of islands around a central lagoon is a/an __________.
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200
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The age of the oldest ocean floor is about __________ million years.
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Layer 1
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The part of oceanic crust made up of pelagic and terrigenous sediment is __________.
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Submarine volcanoes near a subduction zone.
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Island arcs grow from __________.
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Turbidity Currents
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Submarine canyons on continental shelves and slopes are cut by __________.
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Interplanetary Space.
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Most of the water that fills the Earth's oceans came from:
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Coring Devices
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Samples can be taken from the deep sea floor by:
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Magnetometers, Echo Sounders and Microwave Radar Instruments
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Remote sensing devices used to study the ocean floor are:
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Determine the orientation of the Earth's magnetic field at the time the mineral cooled.
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A magnetometer could be used to:
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Basalt
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The Mid-Oceanic Ridge is composed mainly of:
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Older, sinks, and forms the abyssal plains
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Moving away from mid-ocean ridges, oceanic crust becomes:
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Layer 1
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The part of oceanic crust made up of pelagic and terrigenous sediment is:
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Chemosynthesis
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At sea-floor vents, bacteria produce energy from hydrogen sulfide in a process called:
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Mid-oceanic Ridges
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If a series of island arcs collide with a continent over a long period of time, they add to a continent as:
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A black smoker
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When two oceanic plates converge, the sinking plate drags the sea floor down to create:
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Active Continental Margin
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Continental crust and oceanic crust firmly join together at a/an:
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Topographic surface formed as a portion of a lithospheric plate dives into the mantle.
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The continental rise on a passive continental margin is a/an:
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At mid-ocean ridges
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An active continental margin forms:
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Turbidity currents erode terrigenous sediment.
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An active continental margin commonly has a much narrower continental shelf and a considerably steeper continental slope than does a passive margin because:
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Is a seamount that rises above sea level.
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An oceanic island:
