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29 terms

Ch 14 The Ocean Floor

STUDY
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oceanography
the branch of science dealing with physical and biological aspects of the oceans
bathymetry
measurement of ocean depths and the charting of the shape or topography of the ocean floor
sonar
sound navigation and ranging; electronic depth-sounding equipment
submersible
a small underwater craft used for deep-sea research
continental margin
zones between the coasts and the ocean floor basins; includes continental shelves, slopes and rises, as well as, submarine canyons
continental shelf
thick layers of undisturbed sediment near the coasts; wider in the Atlantic Ocean; more narrow in the Pacific Ocean due to volcanic activity
continental slope
the steep grade that leads to the deep-ocean floor; marks the end of the seaward edge of the continental shelf
submarine canyon
a valley in the continental shelf cut during lower sea level, or cut by turbidity currents
turbidity current
water full of sediment created when sand and mud slide off the continental shelf
continental rise
the gently sloping surface at the base of the continental shelf
ocean basin floor
area of deep-ocean floor between the continental margin and the oceanic ridge; includes abyssal plains and volcanic peaks
abyssal plain
very level area of the deep-ocean floor, usually lying near the foot of the continental rise
seamounts
isolated volcanic peaks that rise at least 1000 meters above the deep ocean
mid-ocean ridge
a continuous elevated zone on the ocean floor, along divergent plains where plates are pulling apart
seafloor spreading
the action of plate tectonics producing new oceanic floor at ocean ridges
Where are continental margins widest? Why?
Atlantic Ocean; less earthquake or volcanic activity
terrigenous sediment
sediment made of mineral grains eroded from land
biogenous sediment
sediment made of shells and skeletons of marine life, including algae (calcareous ooze is a type of biogenous ooze)
calcareous ooze
thick sediment caused by dissolving calcium carbonate shells; not found in the deeper ocean because shells dissolve at 4500 meters
siliceous ooze
a type of biogenous sediment; made of shells of diatoms (algae) and radiolarians (single-celled animals)
hydrogenous sediment
minerals that crystallize from ocean water (a small portion of overall ocean sediment)
gas hydrates
made of water and natural gas; found in permafrost and under the deep ocean floor
manganese nodule
hard lumps of manganese (and some other chemicals) found on the ocean floor
How much of the Earth is covered by global oceans?
71%
Name the four main ocean basins.
Atlantic, Pacific, Indian and Arctic oceans
How are sediments deposited on abyssal plains?
turbidity currents carry sediments on the ocean floor
Which ocean has the greatest average depth?
Pacific Ocean
Alvin
submersible used for deep-ocean research
satellites
used to measure differences in ocean-surface heights