CH 16 The Dynamic Ocean

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CH 16 The Dynamic Ocean

• Ocean water is in constant motion and powered by
  many forces
• Forces include wind, Coriolis, gravity, density
  differences
• Ocean currents are masses of ocean water that
  flow from one place to another
• Surface or deep

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Surface Currents

• Movements of water that flow horizontally
• Develop from wind friction
• Gyres huge circular moving current systems (5)
• Coriolis Effect the deflection of currents to
  the right in the NH ( left in the SH) due to
  earths rotation
• Warm currents move from the equator to the poles
• Cold currents move from polar regions to the
  equator
• Cold currents west coast warm currents east
  coast

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Deep Ocean Circulation

• Vertical movement of water
• Upwelling cold water rising from deep layers to
  replace warm surface water
• Brings nutrients to surface(good for fishing)
• Density currents vertical currents of water due
  to density differences
• From temperature(cold) and salinity (high)
• Read pages 451 453

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Waves

• Most waves obtain their energy and motion from
  wind
• Big wind big waves
• Crest top
• Trough bottom
• Wave height distance from trough up to crest
• Wavelength distance from crest to next crest
• Wave period time it takes a full wavelength to
  pass a fixed position

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• Height, length, period of waves depends on 3
  factors
• 1. Wind speed
• 2. Length of time the wind blows
• 3. Fetch (distance across body of water)
• The only thing that really moves forward in a
  wave is energy(particles move in circular orbital
  motion)
• Breakers--Waves that break (fall forward) when
  the depth of the water is one-half of the
  wavelength.

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TIDES

• Please see other PP

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SHORELINE PROCESSES/FEATURES

• BEACH accumulation of sediment along shores.
  (white,pink,tan,black,green)
• SHORELINE (WAVE) FORCES
• Eroding
• Transporting
• Depositing
• Wave impact
• Abrasion
• Refraction bending of waves

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• Wave energy is concentrated at headlands more
  erosion
• Wave energy is weakened in bays more deposition
• Longshore current sediments carried along
  (parallel) to shore due to waves hitting at an
  angle.

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EROSIONAL FEATURES

• Sea Cliff result from waves cutting at the base
• Sea Cave from softer rock being eroded
• Sea Arch cave all the way through
• Sea Stacks roof of the arch collapses
• Wave-cut platform or terrace from continued
  wave action causing a flat eroded area

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DEPOSITIONAL FEATURES

• Spit elongated ridge of sand sticking into the
  bay
• Hook when the spit hooks due to currents
• Baymouth Bar when a sand bar completely crosses
  the bay
• Tombolo a ridge of sand that connects an island
  to the mainland
• Barrier Islands (Outer Banks)

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Stabilizing/protecting shores

• Jetties or groins barrier built at right angles
  to the beach to catch sand
• Breakwaters offshore and parallel to coast
• Seawalls parallel to coast often from the shore
• Beach nourishments
• Natural protectors sand bars, sand dunes,
  fringing reefs, barrier reefs, atolls

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