<P> The continental shelf is the portion of the continental margin that transitions from the shore out towards to ocean . They are believed to make up 7 percent of the sea floor . The width of continental shelves worldwide varies from a 30 meters to 1500 kilometers . It 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 . 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 . Submarine canyons often cut into the continental shelves deeply, with near vertical slopes, and continue to cut the morphology to the abyssal plain . The valleys 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 end of the continental margin . </P> <P> There are two types of continental margins: active and passive margins . </P> <P> Active margins are typically associated with lithospheric plate boundaries . These active margins can be convergent or transform margins, and are also places of high tectonic activity, including volcanoes and earthquakes . The West Coast of North America and South America is considered an active margin . Active continental margins are typically narrow from coast to shelf break, with steep descents into trenches . Convergent active margins occur where oceanic plates meet continental plates . The denser oceanic plate subducts below the less dense continental plate . Convergent active margins are the most common type of active margin . Transform active margins are more rare, and occur when an oceanic plate and a continental plate are moving parallel to each other in opposite directions . These transform margins are often characterized by many offshore faults, which causes high degree of relief offshore, marked by islands, shallow banks, and deep basins . This is known as the continental borderland . </P> <P> Passive margins are often located in the interior of lithospheric plates, away from the plate boundaries, and lack major tectonic activity . They often face mid-ocean ridge s . The East Coast of the United States is an example of a passive margin . These margins are much wider and less sloped than active margins . </P>

Active continental margins include which of the following coasts