Unit 4 Geology

Card Set Information

Unit 4 Geology
2013-02-24 20:36:56
oceans shorelines geology beaches sands

oceans and shorelines
Show Answers:

  1. Approximately what percentage of Earth's surface is covered with oceans?
    Oceans comprise 71% of the Earth's surface.
  2. Name all of the world's oceans
    Atlantic, Indian, Southern, Arctic, Pacific
  3. Compare the relative sizes (1/2 or (1/10th etc) of the other oceans with the Pacific Ocean.
    The Pacific Ocean is the largest. The Atlantic (2nd) and the Indian Oceans are about 1/2 the size of the Pacific. The Southern and Arcitc Oceans are about 1/10 the size of the Pacific. (Note:a search of the internet will each give different square mile areas for each ocean)
  4. A cubic foot of sea water contains how many pounds of dissolved salt?
    One cubic foot of average sea water contains 2.2 pounds of dissolved salts. 
  5. One cubic foot of fresh water usually contains about a _____of dissolved salts. 
    less than one ounce.
  6. Which units are common used to define salt water salinity?(Hint-parts per???)
    Salinity is a measure of dissolved salts of any type. Salinity (salts dissolved in water) is reported in ppt or parts per thousand; example would be the number of pounds of salt in 1000 lbs of water. 
  7. Name three (3) minerals that can be derived by evaporating sea water.
    Halite (table salt), gypsum (sheetrock), calcite (limestone rock), potash (fertilizer), and Epsom salts (laxative).
  8. What is an estuary? Name at least one local example. ALWAYS ON EXAMS
    any bay at the mouth of a river (like Nueces Bay and Copano Bay).
  9. Describe the average relative salinity of Copano Bay  (i.e. brackish, average seawater, hypersaline)
    Copano Bay waters generally have low salinity because of Aransas and Mission Rivers.
  10. We can find brackish water in water wells and seawater. Define brackish water.
    Any water that has salinity between fresh water and sea water.
  11. Sometimes seawater can become hypersaline. Define hypersaline seawater.
    Above average seawater salinities (typical of the Laguna Madre).
  12. Discuss the average relative salinity of Nueces Bay (i.e brackish, average sea water, hypersaline)
    Nueces Bay waters generally averages below ocean salinity. The Nueces Bay will become hypersaline without regular water releases from the upriver dams or during periodsofdroughts. (Under Brackish)
  13. Discuss the average relative salinity of Corpus Christi Bay. (i.e. brackish, average sea water, hypersaline)
    Corpus Christi Bay averages near ocean salinity, principally because of the 50' deep ship channel. (under hypersaline)
  14. Discuss  the average relative salinity seawater of Laguna Madre.
    Laguna Madre averages higher salinity, especially during periods of drought. This confined bay system averages less than 3 feet water depth (except where dredged deeper).
  15. Define the components (parts) of a wave including: crest, trough, height, period (a drawing helps).
  16. Describe how a particle of water actually moves (motion) within a wave that is not next to shore.
    The water particle will move in a circular motion by the waves.
  17. What is the wave base, in regards to wave energy? i.e.- If you want to scuba in calm water, you need to get below the wave base. How do we estimate the depth of a wave base?
    Wave base is the depth at which in the wave energy diminishes to zero that equals one half the wave length
  18. What happens to a wave when it's wave base "hits" the sea floor? (Does the wave get higher or lower?)
    If the wave base hits the surface, the energy is force upward and forward to make a breaker. The wave base hitting the sea floor can also make the sea water appear muddy.
  19. Simply define what a breaker is.
    Defined as a collapsing wave.
  20. Discuss the type of sea floor associated with a spilling breaker and a plunging breaker.
    • Spilling breaker is a wave that breaks on gentle sloping beach slopes. The wave is commonly seen as an advancing line of foam. This type of wave not only pushes sand up to the each but also pushes sand along the beach. (Good for body surfing).
  21. Plunging breaker is____.
    A wall of water that collapses with a "curl". These waves are more frequent in areas of steeper beach slope but also can be found associated with winds or longer period waves. (Usually good for using surfboards).
  22. Discuss the usual affects of a surging breaker.
    Beach-destructive wave that surges up the beach, faces, usually as a wall of water. These waves are associated with high tides and storms or passing ships (sometimes called a storm surge wave).
  23. What are rogue waves and how are they created?
    Usually individual, extremely large waves that combine the fluid energy of many other waves. These waves are generally found near storms and can be very destructive and deadly. 
  24. What are the three types of wave-generated currents are found near the beach?
    Longshore currents, rip current, and undertows.
  25. How do waves generate longshore currents and what direction do these longshore currents move (relative to the shoreline)?
    Generated because all the waves are pushing water up the beach hitting the shoreline obliquely. These longshore currents are found between the beach and the breakers and flows parallel to the beachor shore at speeds of 0.2-4.0 mph. Eventually this water must get back into the sea. 
  26. When do long shore currents become rip currents (i.e. where do rip tides exit?)?
    When the longshore current encounters a gap in the sand bars (slough or trough) or a jetty. 
  27. How can you escape from a rip current?
    To escape a rip current, swim parallel to shore to exit the narrow, swift moving current, and then swim to shore.
  28. What caused high tides and low tides?
    • Frequency of a tide (generally two high and two low tides per day) depends upon:
    • 1.)Irregularities of the shoreline
    • 2.)Variable coastal depth
    • 3.) Size and shape of ocean floor
    • 4.) Frequency of storms
  29. Describe the formation of undertows and to whom are they most dangerous?
    Occurs when waves hit the shore perpendicular and the backwash returns back to the sea "under" the waves. They are considered dangerous for small children and when the waves are very high. (This is different than rip tides.)
  30. Interpret a tide graph and define the following: high tide, low tide, ebb tide and flood tide.
    • Ebb tide: outgoing tide.
    • Low tide:tide at it's lowest level
    • Flood tide: incoming tide.
    • High tide: tide at its highest level.
  31. High tides do not occur at the same time every day. How much later each day would you expect to find the next high tide?
    High tides and low tides (Periods) ususally occur about 50 minutes later for the next tidal period.
  32.  Which sun-moon alignment causes the spring tides that we experience twice every month?
    Biweekly intervals of higher (and lower) tide differences, caused when the sun, Earth, and moon are aligned. 
  33. Which sun-moon alignment causes the neap tides that we experience twice every month?
    Biweekly intervals when the sun , the Earth, and the moon form right angles. 
  34. Examine a moon-Earth-Sun sketch to determine if it demonstrates a spring tide or a neap tide.
  35. How variable are the high tides and low tides for Corpus Christi during a typical month?
    Most of the bays of the Corpus Christi area have on high tide and one low tide a day; however, for various days throughout the month, the tides can vary from 2 tides a day to multiple tides a day. 
  36. Interpret the tidal chart sketch of tides for two months for Corpus Christi.
    On page 8.
  37. What is a Poxigean Spring Tide and how often does it occur?
    They occur when the moon is closest to the Earth (new moon) within the proxigee phase of its orbit. These tides occur once every 18 months.
  38. What is extreme Proxigean Spring Tide and how often does it occur?
    Once every 31 years, when the Earth's elliptical orbit is closest to the sun, a phenomena known as an extreme Proxigean spring tide in which an extremely high and flooding tide is created.
  39. Where in North America do the most extreme daily tides occur. (Bay of ???)
    Bay of Funy (Canada).
  40. How can normal tides affect storm surge waves? (Can they increase the height of the waves?)
    Storm surge tides are destructive tides commonly found during large wind storms. Normal high tides can further increase the heights of storm surges, with destructive consequences.
  41. How is a flood delta created?
    Strong currents associated  with incomind tides can wash this channel-filling sediment into the adjoining bay.
  42. What is the name of a local flood tide delta?
    East of Port Aransas.
  43. What is a Eustatic sea level?
    The global sea level; sea level rises when glaciers melt and sea levels fall when glaciers grow.
  44. What is a drowned valley?
    An old river valley system that has been flooded by a rise in sea level (such as the area occupied by Corpus Christi Bay).
  45. What is the probable effect of rising sea level on our barrier islands?
    As sea level rises, barrier islands "move landward leaving man-made structures behind". Thus these barrier islands are not often submerged by the sea level changes.
  46. What defines the differences between a passive margin coast and convergent coast (i.e.-types of tectonic features).
    • Passive continental margins results in a flat, featureless surface, extending from the continental interior to the edge of the shelf. Minor sea level changes along the GOM (passive margin coast) will have a major impact on the coast.
    • Convergent coast is when the subducting plate is pushing the coastal land up, to form mountains. IN general this means steep-sloping beaches and shorelines with rocky cliffs.
  47. Describe the rising affects of rising sea level on a passive margin coast.
    Minor sea level changes along the GOM (passive margin coast) will have a major impact on the coast.