Admin How did the continental shelf form?
Over many millions of years, organic and inorganic materials formed continental shelves. Inorganic material built up as rivers carried sediment—bits of rock, soil, and gravel—to the edges of the continents and into the ocean. These sediments gradually accumulated in layers at the edges of continents.
Where is continental rise found?
The continental rise completely surrounds Antarctica covering 39.4% of the Southern Ocean (see Table), forming a halo of sediment surrounding the Antarctic continent.
What causes continental rise?
Continental rises form as a result of three sedimentary processes: mass wasting, the deposition from contour currents, and the vertical settling of clastic and biogenic particles.
What is the definition of a continental margin?
Continental margins are defined as active or passive according to the presence or absence, respectively, of plate tectonic activity.
What makes up the margin of the ocean?
The continental margins are the zone of the ocean floor that separate the thin oceanic crust from thick continental crust. Together, the continental shelf, continental slope, and continental rise are called the continental margin.
How does a passive margin form on a continent?
A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting creates new ocean basins. Eventually the continental rift forms a mid-oceanic ridge and the locus of extension moves away from the continent-ocean boundary.
How are earthquakes and volcanoes associated with continental margins?
Earthquakes and volcanoes are associated with active continental margins, which are marked by a landward continental shelf, a much steeper continental slope that ends at an active ocean trench, and an irregular ocean bottom that may contain volcanic hills (Figure 1).