OCEAN BOTTOM FEATURES

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OCEAN BOTTOM FEATURES
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OCEAN BOTTOM FEATURES
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TOPOGRAPHIC FEATURES

• Continental margins
• Shelf up to 300 km wide 150-200 m deep
• Slope 20 - 100 km wide 200 to 2000 m deep
• (Often furrowed by canyons) Slopes 1 in 40.
  
• Rise up to 300 km wide 2000 to 5000 m deep
• (Slopes 1 in 700 to 1 in 1000)
• Trench 600 to 11,000 m deep

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TOPOGRAPHIC FEATURES

• There are 26 trenches in the world ocean
• 3 in the Atlantic Ocean
• 1 in the Indian Ocean
• 22 in the Pacific Ocean
• Deep sea basins about 5000 m deep
• Abyssal Plains are extremely flat,
  sediment-filled
• Abyssal Hills rise from the plains up to 1000 m
• Mid-ocean ridge Interconnected mountain system
  up to 400 km wide Rises to 3000 - 1000 m
• Central rift valley 20 - 50 km wide cuts 1000 -
  3000 m deep into the ridge system

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OCEAN BOTTOM FEATURES

• Seamounts Trenches. Trenches are found
  adjacent parallel to continents island chains.

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• Depths of major trenches exceed 18,000 feet.
• The deepest is the Marianas Trench, 35,810 ft.
  

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• The continental slope gradually rises from the
  abyssal plains climbs as much as 45 deg as it
  approaches land.
• In some areas the slope is interrupted by broad
  wedges of sediment deposits called a continental
  rise.

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• The continental shelf, the region from the
  coastline to the edge of the continental slope,
  covers about 8 of the global seafloor area.
• Average width is 40 miles.

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• Seamounts are isolated mountains rising from
  3,000 to 10,000 feet above the surrounding
  seabed.

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• A beach is an expanse of sand or pebbles along a
  seashore, that is washed by the tide waves.
• Three zones Offshore, foreshore and back shore.

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• Summer time residents of each zone usually
  include surfers, waders, sun bathers.
• The offshore zone has incoming waves that feel
  bottom and curl over as breakers or surf.

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• Foreshore zone is regularly exposed to high low
  tides.
• On the landward edge of the foreshore is the
  beach scarp, usually a rise of several feet
  caused by the eroding action of stronger waves.

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• The Backshore zone extends from the water line to
  the inland area where the sea does not influence
  vegetation.
• The principal feature of the backshore is the
  berm that marks the ordinary limit of a high tide.

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• Most beach sand consists of light-colored quartz
  and feldspar sand grains, the result of
  weathering and erosion of rocks such as granite.

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• Some beach sand comes directly from shoreline
  erosion, but much is created by the action of
  rivers flowing to the sea.

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• Tropical beaches often consist entirely of shell
  and coral fragments.
• Beaches in areas of volcanic activity can be
  black, its sand created by erosion of volcanic
  rock.