Review sheet – Ocean Basins
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Understand that the oceans are not flat and featureless, but instead composed of volcanoes, extensive mountain ranges, canyons, trenches and hills
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Understand that the deepest portions of the ocean are NOT in their center
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Know that bathymetry is the study of ocean floor contours (submarine topography)
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Understand that the invention of the echo sounder (including multibeam sounding) advanced our knowledge of ocean contours, but that satellite imagery is an even better (more accurate) means of mapping seabed features
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Understand that the oceans are made up of mid-oceanic ridge systems, which rise high above the ocean floor in regions of seafloor spreading
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Understand that continental margins are shallow-water areas close to the continents (the submerged outer edges of the continent) that are made up of continental (not oceanic) crust
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Understand that continental margins include the continental shelf and continental slope
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Understand that ocean basins are made up of oceanic (not continental) crust and are the deepwater regions farther away from the continents (includes ocean trenches, ridges, abyssal plains, seamounts, and the continental rise)
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Know that continental margins may either be passive or active; Passive margins face the edges of diverging plates and have little tectonic activity associated with them; Active margins are located near the edges of converging plates and have a high degree of tectonic activity associated with them
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Understand the passive margins are NOT located on plate boundaries (e.g., Atlantic-type, the east coast of the US) while active margins ARE located on plate boundaries (e.g., Pacific-type, the west coast of the US)
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Understand continental shelves are the shallow, submerged extensions of the continent and make up ~7.4% of the ocean’s area
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Understand that the width of any continental shelf can be influenced by its proximity to a plate boundary, localized water currents, and increases or decreases in sea level
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Be able to distinguish the following (ex. Label on a graph): continental slope, shelf break, continental shelf
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Understand that the continental slope is the steep boundary between the continental margin and the ocean basin; the shelf break is the abrupt transition from the gently-sloping continental shelf to the steeply-sloping continental slope
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Know that submarine canyons may extend from the continental shelf and are caused primarily by the erosion of sediments
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Know what a turbidity current is
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Know that oceanic ridges are mountainous chains of young, basaltic rock at the active spreading center of an ocean
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Understand that oceanic ridges cover ~40,000 miles (A LOT) of Earth and can project above the surface in some areas (ex. Iceland)
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Understand that ocean ridges may rise 1.5 miles ABOVE the seafloor

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Know that hydrothermal vents are fissures from which geothermally-heated water rises, and are associated with mid-oceanic ridge systems
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Understand that the superheated water associated with hydrothermal vents does not exist as steam because of the tremendous pressures exerted at their depth
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Know that black smokers are the hottest of the three types of classified vent systems
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Know that the average temperature in the vicinity of a hydrothermal vent is 2-3 times greater than temperatures would be without the vent