O Lecture 10/13/10

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O Lecture 10/13/10
2010-10-18 13:09:21
Coastal Features Continued

Coastal Features Continued
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  1. Beach
    the entire active area of the coast that experiences changes due to breaking waves
  2. Drivers
  3. Where does wave energy converge?
    on headlands
  4. where does wave energy diverge?
    away from adjoining bays
  5. Parallel movement
    • as waves approach shore, they bend so crests are nearly parallel to shore
    • different segments of wave crests move at different speeds
  6. Zig zag motion
    long shore current
  7. long shore current
    zig zag motion
  8. How much can the long shore current speed up to?
    4 km/hr
  9. What does the long shore current speed up with?
    • beach slope
    • wave height
    • wave frequency
  10. How fast are rip currents
    5 mph
  11. How big are rip currents
    15-150 ft wide
  12. What are some features of a depositional coast?
    Delta, Spit, Tombolo, Barrier island
  13. What are the features of a barrier island?
    • beach
    • dune
    • barrier flat
    • salt marsh
    • lagoon
  14. barrier flat
    formed from sand driven through openings during storm
  15. Low marsh
    extends from ~mean sea level to the high neap-tide line
  16. high marsh
    extends to highest spring-tide line
  17. what si the most biologically productivd
    • low marsh
    • land building vegitation
  18. What 3 external forcing functions shape a delta
    • river influence
    • wave influence
    • tide influence
  19. Which one of the 3 external forcing functions shaping a delta forms the most structured delta?
    river influence
  20. Which 1 of the 3 external forcing functions shaping a delta forms the least structured delta?
    tide influence
  21. What determines the final shape of the delta?
    the balance of all three factors
  22. What is the dominating external forcing function of the Mississippi river Delta and how has the delta built the coast line?
    • River dominated
    • switching delta lobes build coastline
  23. estuaries
    body of water surrounded partially by land where fresh and ocean water mix
  24. What are the geologic classifications of estuaries?
    • Drowned River Mouth
    • Fjord
    • Bar-Built
    • Tectonic
  25. Drowned river mouth estuary
    • river under rising sea level
    • ex: Chesapeake Bay
  26. Fjord Geological Estuary
    glacially eroded, deep with sill at mouth
  27. Bar-Built Estuary
    • former low stand of sea level
    • low angle coastlines
    • EX: NC, Florida, Gulf Coast
  28. Tectonic estuaries
    • active plate margins
    • ex: San Francisco Bay
  29. Chemical Characteristics of estuaries
    amount of mixing between freshwater and salt water
  30. The chemical characteristics of estuaries are determined by:
    • shape of estuary
    • volume of river flow at head
    • tidal range at the mouth
  31. What are chemical categories of estuaries categorized by?
    circulation patterns
  32. What are the chemical categories of estuaries?
    • salt wedge
    • well-mixed
    • fjord
    • reverse
  33. Which chemical category of estuaries is becoming more common?