Oceanic Crust = denser (avg. 3g/sq.cm
Continental Crust = less dense (avg. 2.7g/sq. cm)
Denser, oceanic crust tends to subduct under cont.
Passive Margin = neither converging nor diverging
Active Margin = movement of tectonic plates
Continental Shelf = part of ocean that overlies
continental crust (still underwater), extends ~350km
offshore, covered in sediments eroding from land
Continental slope-the transition between the gently
sloping shelf and ocean floor marked by
the shelf break which is typically position at 120 m deep except around Antarctica and Greenland where it is closer to 1000 m
because of the weight of the ice
Continental rise- “apron” of accumulating sediments covering the transition from continental crust to oceanic crust. Only
present along passive margins.
Hydrothermal Vents- “Black smokers” are chimneys formed from deposits of iron sulfide, which is black, and tend to be
higher temperature (350-400 C). “White smokers” are chimneys formed from deposits of barium, calcium, and silicon, which
are white, and tend to be lower temperature (250-300 C) and flow at a lower rate than black smokers. (adapted from NOAA)
Seamounts = volcanos that moved away from magma center (sea mountain); Guyots = weathered seamounts w/ flat top
Ekman Transport=Wind moves surface water, top water layer moves 45 deg from it (bc of Coriolis), Each subsequent layer
of water will move less and less (dragged by friction), Basically domino but force gets weaker; Net movement of water is 90
deg when all layers are considered North Hemisphere = deflects Right, Southern = Deflects left
Thermocline = temperature Pycnocline = density Halocline = salinity
Constructive Interference (Waves) = waves w/ higher wave height; Destructive = dampened height
Refraction = waves move towards shore at an angle, curved shape by interception of leading edge of wave
Diffraction = progression of wave is interrupted by object, new point of departure starts (ie, around an island/pool float)
Reflection = if wave approaches obstruction straight on, it will bounce off and have either destructive or constructive interference
Seiche = standing waves that move back and forth (ie, in a lake/bay, or in a bathtub)
Tsunami/Seismic Wave = long waves at high speeds caused by water displacement (ie, earthquake/landslide)
Gyres = loops of water circulation (clockwise in north and counter in southern hemi, Help redistribute warmth/heat throughout
globe; 5 main ones (north pacific, north atlantic, south pacific, south atlantic, indian ocean)
Northern Hemisphere gyres → clockwise Southern Hemisphere gyres → counterclockwise
Cold salty water (deep water) more dense Thermohaline circulation = global conveyor belt
Western Boundary Current = Fast moving, warm, strong, deep, over smaller volume of ocean (towards equator)
- Gulf Stream, Brazil Current, Kuroshio Current, East Australian Current (EAC), Agulhas Current
Eastern Boundary Current = broad, shallow, colder, flow is more spread out (over larger volume of ocean)
- the California Current, Canary Current, Humboldt (Peru) Current, and Benguela Current
North Atlantic Deep Water (NADW)= Overturning circulation starts with surface water moving into the Norwegian Sea via
Gulf stream (warm salty water), Mixed w/ mediterranean (very salty) & transported into Norwegian sea, Loses enough heat to
sink into deep Greenland Sea, Cold dense water spills into West Atlantic ocean
Antarctic Bottom Water (AABW) = Freezing of Seawater in the WEDDELL SEA (F) leads to the formation of Brine; Brine
sinks & mixes w/ deep circumpolar current water
AABW denser than NADW, AABW spreads from Southern Ocean into pacific, No bottom water sources are found in N pacific
Flow paths for NADW and AABW are determined by bathymetry set by plate tectonics; Bathymetry = measure of depth
