Continental margin

Profile illustrating the shelf, slope and rise

The continental margin is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin is the shallow water area found in proximity to continent.[1] The continental margin consists of three different features: the continental rise, the continental slope, and the continental shelf.[2] Continental margins constitute about 28% of the oceanic area.[1]

Zones of the continental margin

The continental shelf is the portion of the continental margin that transitions from the shore out towards to ocean. Continental shelves are believed to make up 7 percent of the sea floor.[3] The width of continental shelves worldwide varies from a 30 meters to 1500 kilometers.[4] The continental shelf is generally flat, and ends at the shelf break, where there is a drastic increase in slope angle. The mean slope of continental shelves worldwide is 0° 07’ degrees, and typically steeper closer to the coastline than it is near the shelf break.[5] At the shelf break begins the continental slope, which can be one to five kilometers above the deep-ocean floor. The continental slope often exhibits features called submarine canyons.[4] Submarine canyons often cut into the continental shelves deeply, with near vertical sides, and continue to cut the morphology to the abyssal plain.[5] These canyons are often V-shaped, and can sometime enlarge onto the continental shelf. At the base of the continental slope, there is a sudden decrease in slope, and the sea floor begins to level out towards the abyssal plain. This portion of the seafloor is called the continental rise, and marks the outermost zone of the continental margin.[2]