Continental Margins & Ocean Basins. Bathymetry: The Study of Ocean Floor Contours. Early bathymetric studies were often performed using a weighted line to measure the depth of the ocean floor. Advances in Bathymetry Echo sounding Multibeam Systems Satellite Altimetry.
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Early bathymetric studies were often performed using a weighted line to measure the depth of the ocean floor.
Advances in Bathymetry
shallow, submerged edge of the continent.
abrupt transition from continental shelf to the continental slope.
transition between the continental shelf & the deep-ocean floor.
accumulated sediment found at the base of the continental slope.
river erosion during previous glaciation periods
turbidity currents: rapid movement of a mass of sediment down a slope
often caused by earthquakes
An oceanic ridge is a mountainous chain of young, basaltic rock at an active spreading center of an ocean.
hydrothermal vents: spring of hot, mineral- and gas-rich seawater
near seafloor spreading centers
- 1977, Robert Ballard & J. Grassle in Alvin, at 3000 m
near the Galápagos Islands
Hydrothermal vents are sites where superheated water containing dissolved minerals & gases escapes through fissures, or vents.
Seamounts are volcanic projections from the ocean floor that do not rise above sea level. Flat-topped seamounts eroded by wave action are called guyots.
Abyssal hills are flat areas of sediment-covered ocean floor found between the continental margins & oceanic ridges. Abyssal hills are small, extinct volcanoes or rock intrusions near the oceanic ridges.
Trenches are depressions in the ocean floor caused by the subduction of a converging ocean plate.
Island Arcs, chains of volcanic islands & seamounts, are usually found parallel to the edges of ocean trenches.
(left) As two oceanic plates converge, an island arc is formed by volcanic activity.
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abyssal plains: flat, featureless expanses of seafloor
covered w/ sediment
between continental margins & oceanic ridges
why so flat?