Features of the Ocean Floor

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Features of the Ocean Floor
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Exploration Time Line

• 1915
• Scientists aboard the German ship Meteor used
  sonar to map the ocean floor. They used the
  device called echo sounder to produce pulses of
  sound. The ships crew then timed the return of
  the echoes

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German Ship Meteor
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Exploration time line

• 1943
• Jacques Cousteau and Emile Gagnan invented SCUBA,
  which stands for Self Contained Underwater
  Breathing Apparatus. A tank containing
  compressed air is strapped to the divers back
  and connected by a tube to a mouthpiece. SCUBA
  enables divers to explore to a depth of 40
  meters.

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First SCUBA gear 1943
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Exploration time line

• 1960 submersibles
• Vehicles with very thick metal hulls protect
  explorers from extreme pressure and temperature,
  while enabling them to directly observe the ocean
  depths.

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Alvin was the first deep-sea submersible capable
of carrying passengers, usually a pilot and two
observers. Its first untethered dive measured 35
ft. Now, after numerous upgrades and
reconstructions, Alvin can plunge to a maximum
depth of 14,764 ft.
1964
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Exploration Time Line

• 1978 Satellites
• Seasat A was the first satellite in Earths orbit
  to study the oceans. Since satellites make
  millions of observations a day, they provide data
  on rapidly changing and widespread ocean
  conditions. Such data include temperatures, algae
  growth patterns, and even the movement of large
  schools of fish.

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Specific objectives were to collect data on
sea-surface winds, sea-surface temperatures, wave
heights, internal waves, atmospheric water, sea
ice features and ocean topography
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Features of the Ocean Floor

• Continental shelf a gently sloping, shallow area
  of the ocean floor
• 1. The actual boundary of a continent is not its
  coastline, but the edge of the continental shelf.
• 2. Most continental shelves are broad, gently
  sloping plains covered by relatively shallow
  water.
• 3. Water depth over the continental shelves
  averages about 60 meters (200 feet).
• 4. Sunlight penetrates the shallow waters, and
  many kinds of organisms flourishfrom microscopic
  shrimp to giant seaweed called kelp.
• 5. Ocean currents and runoff from rivers bring
  nutrients to organisms that live on continental
  shelves

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Continental Slope

• 1. This marks the true edge of a continentment,
  where the rock that makes up the continent slops
  and the rock of the ocean floor begins.
• 2. The gradient of the slope is lowest off stable
  coasts without major rivers and highest off
  coasts with young mountain ranges and narrow
  continental shelves.
• 3. Most Pacific slopes are steeper than Atlantic
  slopes. Gradients are flattest in the Indian
  Ocean.

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Seamounts

• Mountains that are completely underwater.
• Seamounts - undersea mountains formed by volcanic
  activity - were once thought to be little more
  than hazards to submarine navigation.
• Today, scientists recognize these structures as
  biological hotspots that support a dazzling array
  of marine life.
• The biological richness of seamount habitats
  results from the shape of these undersea
  mountains.
• Thanks to the steep slopes of seamounts,
  nutrients are carried upwards from the depths of
  the oceans toward the sunlit surface, providing
  food for creatures ranging from corals to fish to
  crustaceans.

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Abyssal Plain

• A broad area covered with thick layers of mud and
  silt.
• The plains are largest and most common in the
  Atlantic Ocean, less common in the Indian Ocean,
  and even rarer in the Pacific, where they occur
  mainly as the small, flat floors of marginal seas
  or as the narrow, elongate bottoms of trenches.

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Mid-Ocean Ridge

• A continuous range of mountains that winds around
  Earth, much as the line of stitches winds around
  a baseball.
• At the top of the mid-ocean ridge, about 2
  kilometers above the abyssal plain, but still 1
  kilometer below the surface.
• It consists of two parallel chains of mountains
  separated by a central valley.

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Sonar

• Sound Navigation and Ranging, is a system that
  uses sound waves to calculate the distance to an
  object.
• The sonar equipment on a ship sends out pulses of
  sound that bounce off the ocean floor.
• The equipment then measures how quickly the sound
  waves return to the ship.
• Sound waves take longer to return if the ocean
  floor is farther away.