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Continental Margin

The Continental Rise

Sediments eroded off continental land, after being carried across the shelf and down the continental slope, are finally deposited at the base of the slope in a region of the ocean known as the continental rise. By some estimates, half of all the sediments laid down on the face of the planet are found in the continental rise.

In many regions, the continental rise looks very much like a river delta such as the one found at the mouth of the Mississippi River. In fact, these underwater deltas may also include a network of channels and natural levees similar to those found in the area of New Orleans. One of the most thoroughly studied sections of the continental rise is the Amazon Cone located northeast of the coast of Brazil. The Amazon Cone has a total width of about 30 mi (50 km) and a depth of about 1,000 ft (300 m). It is bisected by a primary channel that is 800 ft (250 m) deep and as much as 2 mi (3 km) wide.

See also Ocean zones.


Resources

Books

Duxbury, Alyn C., and Alison Duxbury. An Introduction to the World's Oceans. MA: Addison-Wesley Publishing Company, 1984.

Golden, Fred, Stephen Hart, Gina Maranto, and Bryce Walker. How Things Work: Oceans. Alexandria, VA: Time-Life Books, 1991.

Hancock, Paul L., Brian J. Skinner, and David L. Dineley, eds. Oxford Companion to the Earth. Oxford: Oxford University Press, 2001.

Skinner, Brian J., and Stephen C. Porter. The Dynamic Earth: An Introduction to Physical Geology. 4th ed. John Wiley & Sons, 2000.

Thurman, Harold V., and Alan P. Trujillo. Essentials of Oceanography. 7th ed. Englewood Cliffs, NJ: Prentice Hall, 2001.

Woodhead, James A. Geology. Boston: Salem Press, 1999.


David E. Newton

KEY TERMS

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Continental rise

—A region at the base of the continental slope in which eroded sediments are deposited.

Continental shelf

—A relatively shallow, gently sloping, submarine area at the edges of continents and large islands, extending from the shoreline to the continental slope.

Continental shelf break

—The outer edge of the continental shelf, at which the ocean floor drops off quite sharply in the continental slope.

Continental slope

—A steeply-sloping stretch of the ocean that reaches from the outer edge of the continental shelf to the continental rise and deep ocean bottom.

Submarine canyon

—A steep V-shaped feature cut out of the continental slope by underwater rivers known as turbidity currents.

Turbidity currents

—Local, rapid-moving currents that result from water heavy with suspended sediment mixing with lighter, clearer water. Causes of turbidity currents are earthquakes or when too much sediment piles up on a steep underwater slope. They can move like avalanches.

Additional topics

Science EncyclopediaScience & Philosophy: Condensation to CoshContinental Margin - Continental Shelf, The Continental Slope, Submarine Canyons, The Continental Rise