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Divergent
2 tectonic plates move apart from one another (mid ocean ridge)
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Convergent
2 tectonic plates move toward one another
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Transform ("Strike Slip")
2 tectonic plates slide past one another at an angle (subduction zone)
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Subduction
- process where 2 tectonic plates converge together
- the more dense plate subducts under the less dense plate
- results in volcanic activity
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Passive Continental Margins
- not on plate boundaries
- lack active volcanoes and earthquakes
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Active Continental Margins
- on plate boundaries
- active volcanoes and earthquakes
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Lithongenous Sediment
gravel, sand, silt, clay
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Biogenous Sediment
- shells, bones, teeth, droppings
- ooze= sediment with over 30% biogenic material
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Hydrogenous Sediment
chemical precipitates= lime, salt, sulfides
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Continental Slopes
- cut by huge submarine canyons
- slopes seaward at an average of 4 degrees
- bottom=edge of continental crust
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Island Arcs
- arcuate chain of islands
- explosive stratovolcanoes, earthquakes
- new continental crust forming due to melting of crust by subduction zone
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Trenches
- Depth: 11,035 m
- Length: 4,200 km
- Width: 120 km
- Mark each convergent plate boundary
- Lead to subduction zone
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Photic Zone
- Depth: 20-60 meters
- Depends on turbidity
- Sufficient light for photosynthesis
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Aphotic Zone
- insufficient light for photosynthesis
- most of the ocean
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Temperature Zones
- Surface
- Thermocline
- Deep Zone
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Thermocline
zone of rapidly changing temperature with depth
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Salinity Zones
- Surface
- Halocline
- Deep Zone
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Halocline
zone of rapidly changing salinity with depth
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Density Zones
- Surface Zone
- Pycnocline
- Deep Zone
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Pycnocline
Zone of rapidly changing density
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Speed of Sound in Water
- 1,500 m/s
- Depends on density, temp, salinity, pressure, and depth.
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Prevailing Winds
controlled by the sun's heat and the earth's rotations
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Coreolis Effect
- apparent deflection of north and south moving material on a rotating planet
- cause by differenes in rotation speed between the poles and the equator
- currents deflect to the RIGHT of their path in northern hemisphere
- currents deflect to the LEFT of their path in southern hemisphere
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Factors of the Coreolis Effect
- highest values of deflection occur at the poles
- 3 variables define it:
- velocity of object (linear)
- rotation speed of earth
- latitude of position
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Gyres
loop like currents of water driven by winds, continent placement, and Coreolis effect
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Surface Currents
- affect water down to 2,000 m
- major agents of cold and warm water distribution
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Thermohaline Currents
- powered by density, controlled by temp and salinity
- dense water masses sink and light ones rise
- cause deep circulation of the oceans
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Upwelling Currents
- deep water returns to the surface
- cold, nutrition rich water creates blooms of high fertility
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Effects of Ocean on Climate
- moderates temp-oceans act as heat sinks
- increases precipitation-evaporation
- warm and cold currents transport heat-up-/downwelling
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El Nino
trade winds decline
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La Nina
trade winds increase
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