oceans exam 2

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  1. Seawater composition

    -avg salinity 3.5 % or 35%

    -most salt in seawater is sodium chloride

    -it is made up of sodium chloride, metals, other slats, dissolved gases. 3.5 dissolved mineral substances
  2. Thermocline
    layer of rapid temperature change

    -absent at high latitudes

    - depth at which the rate of decrease temperture with increase of depth is the largest.
  3. Pycnocline
    a layer, gradient of changing density. A thin layer of ocean water witha density that increases rapidly with depth.
  4. Halocline
    layer of rapid salinity change

    -corresponds to thermocline
  5. how is salinity measured?
    parts per thousand

    avg 3.5 or 35 percent.
  6. What add to salinity
    -cheminal weathering of rocks on continents

    -volcanic eruptions

  7. what takes salinity away?
    -chemical precipitates

    -plants and animals build hard parts
  8. Active continental margins
    -ocean lithosphere subducted beneath continent

    -pacific rim

    - associated with deep ocean trenches

    -experience volcanic eruptions and earthquakes
  9. Passive continental margins
    -not associated with plate boundaries

    -experience little volcanism and few earthquakes

    - carries the debris ithat is eroded from continents to where it drains.
  10. deep ocean basins
    - 30% of earth's surface

    - features abyssmal plain, deep sea trenches, seamounts, oceanic plateaus
  11. (deep ocean basin) Abyssal plains
    flat, deep ocean floor. it is almost featureless because a thick layer of sediment covers the hills and valleys of the ocean floor below it.

    -thick accumulations of sediment
  12. (deep ocean basin) Seamounts
    -broad volcanic peaks, isolated volcanic peaks

    -many form near oceanic ridges
  13. (deep ocean basin) oceanic plateaus
    - similar to continental flood basalt provinces
  14. Mid oceanic ridge
    -longest topographic feature on Earth

    • -divergent plate boundary
    • new crust created.

    -they are broken segments, seprated by transform faults
  15. (coastal environment) Coast
    area behind the beach
  16. (coastal environment) beach
    • -back shore
    • dunes or berms

    • -foreshore
    • high and low tidal reaches
    • surf zone
  17. (coastal environment) Near shore
    -beach deposition of sediments

  18. (coastal environment) Offshore
    -little to no beach sediments
  19. cause for Tides
    earth, sun, moon gravitational interactions
  20. Spring tide
    extreme high and low tides
  21. Neap tide
    moderate high and low tides
  22. (waves) Breakers
    -cause by frictional dragging of a orbital motion along shore floor

    -at sea the waves do not reach the bottom, by the coast it does.
  23. (waves) Orbital motion
    -it is broken down in coastal areas
  24. (waves) wave refraction
    -water waves can be refracted or bent.
  25. (wave refraction) uneven coast
    -bays or coves cover them

    -waves refract and weaken by the time they reach coves
  26. (wave refraction) Even coast
    -it smooths out the coast line

    - if left alone, will usually result in no net loss or gain of beach sediment
  27. Longshore current
    current drives the longshore drift of beach sediments

    -happens in an even coast.
  28. erosion on sea cliffs
    these may collapse

    -wave erosion is focused at the base of the cliffs
  29. (beach erosion) formations
    barrier beach and barrier island
Card Set
oceans exam 2
oceans topic
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