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80 Cards in this Set
- Front
- Back
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Bathymetry |
The study of ocean floor contours |
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Echo Sounding |
Sonar used to determine depth of water. Transmits sound waves into water, and uses time interval between emission and and return of pulse. |
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Multibeam |
Combine many echo sounders |
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Satellite Alimetry |
Measures the sea surface height from orbit using radar pulses |
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Ocean Floor Topography Varies w/ Location |
Ocean basins are not shaped like bath tubs
tectonic forces shape the sea bed |
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Avg. elevation of continents |
840 Meters (2,760 ft.) |
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Avg. Depth of oceans |
-3,800 Meters (-12,450 ft.) |
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Continental Margin |
Zone of the ocean floor that separates the thin oceanic crust from thick oceanic crust |
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Passive Continental Margin |
Continental Margin facing the edges of divergent plates
Little EQ or volcanic activity
Atlantic-Type Margins |
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Active Continental Margin |
Continental Margin facing the edges of converging plates
High EQ and volcanic activity
Pacific-Type margins |
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Continental Shelf |
-Submerged Extension of Continents -Underlain by granitic continental crust -Sediments: from erosion of land -Gently sloping seaward -Oil and Minerals -Water Depth: Avg. 75 meters (250 ft.) |
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Continental Shelf Shaped by |
-Tectonics (Passive vs. Active) -Ocean Currents (Fast flowing vs. Slow flowing) -Sea Level (Low Sea Level vs. Fast Sea Level) |
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Wider Vs Narrower Continental shelves |
Passive=wider (Gulf of Mexico) Active=narrower (So. Cal.) |
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Continental Slope |
-Transition between continental and the deep ocean floor -Sediments: Mainly from the shelf -Steeper than the continental shelf -20 km (12 mi.) wide - -3,700 m. depth -Bottom of slope is true edge of continent
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Shelf Break |
-Abrupt transition from continental shelf to continental slope -140m (460ft) -Surprisingly constant depth worldwide |
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Submarine Canyons |
-Feature of some continental margins that cut into continental shelf and slope; often terminating on the deep-sea floor in a fan shaped wedge of sediment -Form at junction of continental shelf and slope |
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Turbidity Current |
-Fast dense current of water that carries sediment off shore -Scouring canyons -EQ along active margins can trigger TC |
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Continental Rise |
-Forms as sediment accumulates -Often an apron of sediment that covers the bottom of the continental slope -Widest and thickest in Bay of Bengal |
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Features in Deep Ocean Basins |
Features of deep ocean floor: -Oceanic Ridges -Hydrothermal Vents -Abyssal Plains and abyssal hills -Seamounts and Guyots -Trenches |
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Oceanic Ridge |
-Mountainous Chain of young basaltic rock at an active spreading center of an ocean -Spreads 65,000 km around Earth |
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Hydrothermal Vents |
-Sites where superheated water containing dissolved minerals and gasses escapes through fissures or vents -Hot springs on active oceanic ridges -Black Smokers: 2-5 (Ph), 300-400 (t), fast spreading ridges -White Smokers: 10-11 (Ph), 100 (t), slower |
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Abyssal Plains |
-Flat, cold, sediment-covered ocean floor between continental rise and oceanic ridge (deeper than 3,700 m) -Between continental margins and ocean ridges
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Abyssal Hills |
-Small sediment covered extinct volcanoes or rock intrusions: we think they are associated with sea floor spreading |
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Seamounts |
-Volcanic Mountains (bigger than Abyssal hills) that rise from the ocean floor and never grow tall enough to come to the sea surface -submerged margin of continent -slope gently seaward -made of granite (continental) -made of basalt (oceanic) |
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Abyssal Hills vs. Seamounts |
Abyssal; Small, sediment covered, extinct volcanoes, less than 200m high, associated with seafloor spreading, not as steep but more abundant Seamounts; Inactive volcanoes, over 1km in height, form at spreading centers but some at hotspots, steeper and less abundant |
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Epicenter |
Point where EQ initiates |
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Guyot |
Isolated flat underwater mountain (seamount) |
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Island arc |
Chain of volcanoes that arc off of a convergent boundary |
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Surface contours of Mars better known than contours of Ocean floor |
Mid oceanic ridge is most prominent feature. Water circulates through hot oceanic ridges every 10 million years |
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Hydrologic Cycle |
-Solar Powered -80% of precipitation falls back into ocean
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Earth's water budget |
Oceans: 97.5% Glaciers and Icecaps of GL&ANT: 1.8% Fresh Water in rivers, lakes, groundwater, and wetlands: .64% |
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Water Molecule |
-Two hydrogen atoms share electrons w/ one oxygen atom -held together by covalent bonds -acts as if it has negative and positive ends -O end is more negative than H end -Polar (positive and negative side) -Hydrogen bonds form when positive end of molecule bonds to negative end -Hydrogen gives water surface tension |
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State of water (gas) |
-water vapor -fills closed container uniformly -molecules in high speed motion -collisions and rebounds occur -density very low -readily condensed into smaller volume |
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State of water (liquid) |
-Free upper surface -Flows freely to lower level -Molecules close together, slide easily past each other |
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State of water (ice) |
-crystalline -strong and rigid -fractures under sudden stress -molecules in tight geometrical structure -high density |
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State |
Expression of internal form of substance |
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Density decreases as water freezes |
-angle changes from 105-109 -water expands 9% as crystals form -Ice takes up less space |
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Thermal Characteristics of Water |
-very high heat capacity -resists changing temperature when heat is added or removed |
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Heat Capacity |
Measure of heat required to raise the T of 1g of a substance by 1degree c.
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Thermal Inertia |
Tendency of a substance to resist change in T with the gain or loss of heat energy |
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W. Coast Vs. E. Coast |
-Heat capacity allows water to regulate T of oceans and atmospheres -Wind from W. to E. -San. Fran. moderate (ocean) -Norfolk bigger T range (land) -Ocean demonstrates thermal inertia |
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Surface Water moderates global T |
-warm water is carried N.ward -Global Warming: more energy and thermal expansion |
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Water is Powerful |
NaCl (Salt): Ionic bond: Na loses an electron and becomes positively charged, Cl gains an electron and becomes negatively charged
+H is attracted to -Cl -O is attracted to +Na |
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Salinity |
Total concentration of dissolved inorganic solids in dissolved in water |
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Principle of Constant Proportions |
Ratio of dissolved solids is constant even if the relative amounts are changing. Oceans are said to have chemical equilibrium. |
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Gasses dissolve in SW |
-Nitrogen in SW 48% in atm. 78% -Oxygen SW 36% in atm. 100% -Carbon D. SW 15% in atm. .03% |
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Acid-Base balance (scale) |
Acid: substance that releases hydrogen ion in solution
Base: substance that combines with hydrogen
Alkalinic: basic |
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Acid-Base balance (water) |
-water is neutral (7)
-SW is slightly basic (7.8) despite uptake of CO2
-Ocean is becoming more acidic (CO2) |
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Density Stratification |
-Ocean is stratified by density
-density is function of T and salinity
-Cold salty water denser than warm less salty |
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Light |
-Light does not travel far through ocean
-Photic Zone: Thin film of lighted water at top of world ocean (doesn't extend deeper than 200m)
-Aphotic Zone: Dark ocean below depth light can penetrate |
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Sound |
-Travels deeper than light -Faster in SW than air -Faster as T and pressure increase |
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Heat vs. Temperature |
Temperature is response to input or removal of heat |
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Thermocline |
Layer in body of water where T changes more rapidly than layer above or below |
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Pycnocline |
Layer where density is greatest |
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Halocine |
Caused by strong vertical salinity gradient |
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Atmosphere Composition |
-Nitrogen -Oxygen -Water Vapor |
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Facts about atmosphere |
-Water vapor occupies 4% of volume -humid air is less dense than dry air -lower atmosphere homogeneous gases -density of air determined by T and water content |
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Solar Heating of Earth |
-varies with latitude -near poles light filters through more -no light during local winter -mid-latitudes receive more heat during summer than winter -heat is transferred by wind and currents -mid-latitude affected by seasons (axis tilt) -If earth were not smooth rotation sphere, 2 atmospheric convention cells develop |
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Factors governing global air circulation |
-uneven solar heating -coriolis effect: circulation cells on rotating sphere |
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Coriolis effect |
Path of moving objects are deflected: -Clockwise in N. hemisphere -Counter Clockwise in S. hemisphere |
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Atmospheric Circulation Cells (Hadley) |
-tradewinds -Easterlies centered around 15n 15s |
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Atmospheric Circulation Cells (ferrel) |
-mid-lat circulation cell -Westerlies 45n 45s |
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Atmospheric CC (polar) |
-Denser -Does not mix well with ferrel winds -Boundaries between cells wind moves vertically |
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Doldrums |
-Surface winds of Hadley Cells converge (low pressure=rising air) -same as intertropical convergence zones
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Horse Latitudes |
-Between Hadley and Ferrel -sinking air (high pressure) |
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Surface currents driven by wind |
-10% of water involved in currents -water flowing horizontally in uppermost 400m -above pycnocline
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Gyres |
Circuit of mid-latitude currents around periphery of ocean basin |
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Storms |
-variations in large scale atmospheric circulation -can form between air masses (frontal) -within one air mass (tropical cyclones)
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Cyclones |
N-counter S-clockwise |
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Hurricane damage |
-storm surge -wind damage 74mph -fresh water flooding |
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Flow of ocean water driven by |
Wind (surface currents): wind driven movements of water
Gravity (Thermohaline currents): slow, deep currents, that affect water below pycnocline
Affect: temperature, climate, biological productivity |
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Effect of surface currents on climate |
Transfer heat from tropical to polar regions affecting mid-latitudes |
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Surface current composition |
-10% of water involved -water flowing horizontally in uppermost 400m -above pycnocline |
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Ekman Spiral |
-theoretical model on water of wind moving over ocean -b/c of coriolis effect ocean surface layer shifts -45d to right in n -45d to left in s |
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Eddy |
Swirling of fluid and reverse of circulation when it flows past obstacle |
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Geostrophic current |
Currents in gyres |
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Western Boundary Currents |
-narrow, deep, fast currents that occasionally form eddies
-Gulf stream (largest) -300x flow of amazon -water vapor forms clouds -waters in gulf stream depleted of nutrients -water over continental slope teems with life |
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Eastern Boundary Currents |
-Transport cold water equatorward -Shallow currents -Broad currents (600m wide) -poorly defined boundaries -eddies tend not to form
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Garbage Patches |
Center of Gyres |
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Turtle |
-Female loggerhead -beach of florida-gulf stream-frozen north -swims around north atlantic to africa -back to beach where she was born -chance of survival low -2 mil. hatched each season -1/10,000 return safetly |
