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Ocean Regions: Ocean Floor - Continental Margin & Rise

Surrounding nearly all continents is a shallow extension of that landmass known as the continental shelf. This shelf is relatively shallow, tens of meters deep compared to the thousands of meters deep in the open ocean, and extends outward to the continental slope where the deep ocean truly begins.

Sediment from the erosion of land surfaces, washed into the sea by rivers and waves, nourishes microscopic plants and animals. Larger animals then feed upon them. These larger animals include the great schools of fish, such as tuna, menhaden, cod and mackerel, which we catch for food.

The continental shelf regions also contain the highest amount of benthic life (plants and animals that live on the ocean floor).

Diagram of continental shelf, slope & rise

The continental slope connects the continental shelf and the oceanic crust. It begins at the continental shelf break, or where the bottom sharply drops off into a steep slope. It usually begins at 430 feet (130 meters) depth and can be up to 20 km wide. The continental slope, which is still considered part of the continent, together with the continental shelf is called the continental margin.

Submarine canyons cut through many of the continental margins. Some of these have been carved by turbidity currents, which are bottom currents that carry lots of sediment.

Past the continental slope, we find the continental rise. As currents flow along the continental shelf and down the continental slope, they pick up and carry sediments along and deposit them just below the continental slope. These sediments accumulate (gather) to form the large, gentle slope of the continental rise.

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