The Ocean Basins

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The Ocean Basins
Physical Oceanography
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Features of the Ocean Basins

• Continental margin portion of ocean made up of
  continental crust

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Features of the Ocean Basins

• continental shelf flat part of continental
  margin covered by shallow ocean water

Formed by changes in sea level Avg depth 60 m
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Shelf

• Relatively shallow
• 0 200 m
• Relatively flat with a gradient of 2 m drop per
  kilometre

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Features of the Ocean Basins

• continental slope boundary between continental
  crust and oceanic crust - The average angle
  displayed by the slope is about 5 degrees.

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Features of the Ocean Basins

• submarine canyons deep, v-shaped valley that
  cuts through shelf slope

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Features of the Ocean Basins

• continental rise wedge of sediments that
  separates slope from ocean floor

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Features of the Ocean Basins

• abyssal plain (floor) very flat areas at depths
  of 3-5 km

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Features of the Ocean Basins

• mid-ocean ridge mountain range on ocean floor
  due to seafloor spreading

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Features of the Ocean Basins

• trench deep narrow valleys along the edges of
  subduction zones in the ocean floor 90 of
  trenches are found around the Pacific rim.

Marianas Trench in Pacific ocean is the deepest
point on earth - 10,668 meters
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Bathymetric Charts show the contours and depths
of the seafloor topography
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General Slope Features

• Sharp break from the shelf
• Angle is gentle, averaging less than 5 degrees
• Continues to a depth of 3600 m
• Often carved by deep canyons - Hudson Canyon is
  famous in N.A.

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Submarine Canyons

• V-shaped
• Hudson Canyon steeper than the Grand Canyon
• Form deep sea fans from sediments
• Originated from rivers during ice ages

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The Gully!

• Submarine canyon off Nova Scotia
• Marine protected area because of the rare corals
  found there
• The natural gas pipeline goes right by
  itproblems?

The Gully
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Turbidity currents

• Turbidity currents are caused by the slumping of
  sediments from the continental slope.
• can travel at over 55 km/h
• can spread 700 km
• Can damage underwater pipelines, transatlantic
  cables

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Rise

• Slope about ½ degree toward the abyssal plain
• Sediment deposition from continent
• Range from 100 to 1000 km in width
• Only occur along passive margins, often off the
  mouth of large rivers

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Another look ?
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Features of the Ocean Basins

• seamount underwater volcanic mountain (some
  more than 1000 m high)

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Features of the Ocean Basins Atolls

• A ring shaped island of coral reefs and coral
  debris. These often form over sinking inactive
  volcanoes.

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Features of the Ocean Basins

• coral reef limestone structures containing
  shells of animals that surround volcanic islands

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Features of the Ocean Basins

• guyot a flat-topped submerged seamount due to
  erosion

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Features of the Ocean Basins

• rift valley deep crevice in between mountain
  ranges

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Which coast has the wider shelf?