l l Learning Objective l Continental Margins l Deep-Ocean Basins l Mid-Ocean Ridge
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2. Deep-Ocean Basin

       The deep-ocean basin, which begins immediately after the continental rise, is highlighted by the abyssal plains. Abyssal plains may be the flattest places on Earth.The abyssal plain found off the coast of Argentina has less than 3 m of relief over a distance exceeding 1300 km. Oceanographers have concluded that the abyssal plains consist of thick accumulations of sediment that has buried an otherwise rugged ocean floor.Occasionally the protruding summit of a buried volcano can be seen interrupting the flat topography of an abyssal plain.Turbidity currents are responsible for depositing this sediment.The Atlantic Ocean has more extensive abyssal plains than the Pacific, due to it having fewer trenches which can act as traps for the traveling sediment.The ocean floor is almost completely covered with sediment.Although deposits of sand-sized particles are found on the ocean floor, mud is the most common sediment covering the region.The average depth of the sediment accumulation on the ocean floor varies between 500 to 1000m.However, the depth may approach 10 km in the trenches, which act as a trap for sediment.