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GHHS Oceanography


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Powerpoint notes for High school oceanography unit in Earth Science. Course being taught in North Carolina

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GHHS Oceanography

  1. 1. Oceanography Beaches & Unit 8
  2. 2. Follow the directions at the bottom of the page. COLOR it LAST!!! Use your textbook to find the features it asks for. Helpful Book Pages: Page 31 Page 449 Pages 396-397
  3. 3. The Ocean Floor - The Vast World Ocean Origin of the Oceans How old is the Earth? 4.6 billion years old Where did the water come from? 1. Comets and Meteorites: - Carry lots of water, which transferred to Earth upon impact 2. Volcanism: -volcanic gas has mostly water vapor and CO 2 -The CO 2 and other gases formed the Earth's atmosphere -As the Earth cooled, the water vapor condensed, forming the oceans.
  4. 4. he Blue Planet arth is known as the " Blue Planet" because ~71% of it is covered y oceans. -Average Depth of the Oceans: 3800 m (3.8 km) -Where is most of the water - Northern or Southern Hemisphere? Southern -All oceans are really one big body of water. -97% of the water on Earth is found in the oceans. Only 3% is freshwater. -OCEANOGRAPHY = study of Earth's oceans
  5. 5. Sea Level = level of the ocean's surfaces . -Sea Level has risen and fallen by hundreds of meters due to the.. -Ice Caps melting (H 2 O level rises) and Glaciers expanding (H 2 O level falls) -Sea Level is also affected by tectonics. -TECTONICS = movement of Earth's landmasses . -Tectonics can change the level of the seafloor, thus changing sea levels. -Currently, sea level is rising 1-2mm/year due to melting glaciers
  6. 6. GEOGRAPHY of the OCEANS There are 4 major Oceans: -Pacific, Atlantic, Indian, & Arctic Largest = Pacific Smallest = Arctic Sea Ice: Ice is ( more / less ) dense than water, so it floats. SEAS = smaller than oceans, and partially or fully landlocked. -All seas and oceans belong to one global ocean, whose waters are thoroughly mixed.
  7. 7. Mapping the Ocean Floor The topography of the ocean floor is as diverse as that of the continents. Bathymetry = measurement of the ocean floor ( bathos = depth, metry = measurement) Began with the ship " Challenger" in the 1870s -Although today's technology is much more sophisticated!! SONAR was first used in the 1920s to map the seafloor features of the S. Atlantic Ocean. SONAR = SOund NAvigation and Ranging How does it work? Uses echoes of sound, return time, and velocity of sound in water to measure depth. -See p. 398 in text. Drain the Ocean- Nat Geo
  8. 8. Side-Scan Sonar = aim SONAR at angles . t is used to map underwater hills, trenches, ridges, etc. SATELLITES continually gather information about the ocean floor. -Data has shown that the ocean surface is not totally flat... -Why?? - Gravity attracts water toward regions where massive ocean floor features occur. - Mountains/Ridges have elevated water. Trenches have depressions.
  9. 9. SUBMERSIBLES (small underwater crafts) give us much data. Manned crafts: - Trieste - Jacques Piccard (1960) -Went to the Mariana Trench (10,912m) - Alvin - 4000m - Sea Cliff II - 6000m Unmanned crafts: called AUVs (autonomous underwater vehicles) Deep Sea Exploring
  10. 10. Use pages 401-406 in your textbook, defining each term and labeling the diagrams. “See” the Ocean Floor Continent Trench Continental Mid-Ocean Margin Ridge Continental Rift Valley Shelf Volcanic Island Continental Fringing Reef Slope Barrier Reef Continental Rise Atoll Submarine Define but do not label: Canyon Seafloor Spreading Abyssal Plain Hydrothermal Vent Seamount
  11. 11. Work on Worksheet
  12. 12. Fringing- directly attached to the shore of a volcanic island. No lagoon present. Atoll- Circular coral reef that surrounds a central lagoon of quiet water. Forms on top of the cone of a submerged volcano island. Barrier- A lagoon of open water separates reef from the nearby land. Largest is Great Barrier Reef, Australia (1,200 mi long and 62 mi wide) Types of Coral Reefs
  14. 14. 14.1 - 14.2 Quiz: 1. Largest Ocean 2. Ocean that is on the EAST side of Africa 3. Name one place where our ocean's water came from. (there were 3) 4. What does SONAR stand for? 5. Name the 3 parts of the Continental Margin, IN ORDER, going from the beach into the ocean. 6. What is the name for the deep, very flat part of the ocean floor? 7. Which comes first: Atoll, Fringing Reef, or Barrier Reef? 8. What is the name for a dormant seamount that has been eroded? 9. What is the name for the deep cut in the ocean floor that is only found in the abyssal plain? Word bank (some answers are here, but not all of them!) Continent Abyssal plain Seamount Volcanic island Submarine canyon Continental shelf Continental margin Guyot Trench Mid-ocean ridge Continental rise Rift valley Continental slope
  15. 15. 1. 2. 3. 4. 5. 6. 7. 8. 9. Pacific Indian Any of these: meteorite, comets, volcanoes Sound Navigation and Ranging 3 points: IN ORDER: Cont.Shelf, Cont.Slope, Cont.Rise ANSWERS!!! Abyssal Plain Fringing Reef Guyot Trench
  16. 16. Brainpop-Ocean Floor Continental Margin (shelf, slope, rise) Inter-Tidal Zone Area of shoreline between high and low tides Con tinen tal sh e High Tide Low Tide lf ~200m Photosynthetic Zone: light penetrates for photosynthesis. Up to 150 m (488ft) nta ne nt i Co pe Slo THERMOCLINE ~200-100ft Bathyal Zone: Darkness l MAJOR OCEANIC ZONES Co n Benthic Environment: tine Ocean bottom or floor nta l Ri se 4000 m Abyssal Zone: 4000-6000m Abyssal Plain >6000m Hadal Zone
  17. 17. Work on the Review & Reinforcement WKST “Physical Properties of the Ocean Life Zones”
  18. 18. Ocean Water and Ocean Life THE COMPOSITION OF SEAWATER SALINITY •Salinity: the total amount of solid material dissolved in water. • Seawater is about 96.5 % water and 3.5 % dissolved salts. • Expressed as grams of salt per kilograms of water (or parts per thousand - ppt) • Average salinity: 35 ppt (3.5 %) • Most abundant salt in seawater: sodium chloride (NaCl) •Seawater also has dissolved gases and nutrients •Sources of Sea Salts: chemical weathering of rocks and volcanism
  19. 19. Processes Affecting Salinity: – Adding water decreases salinity: precipitation, runoff, icebergs & sea ice melting – Losing water increases salinity: evaporation, formation of sea ice o How does salinity increase when sea ice forms? When ice forms, salt is left behind in the water.
  20. 20. OCEAN TEMPERATURE VARIATION ·Surface Layer Temperatures: Varies with the amount of solar radiation received, which is a function of latitude. Middle latitudes (near the equator) have higher temperatures, and vice versa.
  21. 21. Temperature Variation with Depth: – Colder water is denser than warmer water, so cold water will sink. – Deeper = Colder! –Three temperature layers: – Surface layer: warmest – Thermocline: (300m-1000m) a rapid change of temperature with depth. – It creates a vertical barrier to many types of marine life. – Bottom layer: coldest – In polar regions, the surface layer & thermocline don't exist because it's too cold.
  22. 22. OCEAN DENSITY VARIATION – Density varies with depth due to both temperature and salinity. – Denser Water = ( colder or warmer ) and ( salty or fresh ) ... why floating is easier in the ocean! Density Lab
  23. 23. Warmup Quiz: 1) Does adding or losing water increase salinity? 2) Name one way the Earth naturally decreases salinity. 3) What does PPT stand for? 4) Name the ocean region: the temperature rapidly changes as you go deeper. 5) In the ocean, the deeper the water, the colder / warmer and saltier / fresher it is.
  24. 24. The Dynamic Ocean OCEAN CIRCULATION & WAVES AND TIDES Ocean Waves 4 Movements of the Ocean: Waves, Tides, Currents & Upwellings WAVES = Rhythmic movement that carries energy through space or matter - Generated mainly by wind - As a wave passes, water moves in a circle, returning to its original position. -The water doesn't move forward , only the energy. (water)
  25. 25. ve Measurements: ighest point = crest. Lowest point = trough. istance from Crest to Trough = wave height. istance from Crest to Crest (or trough to trough) wavelength. Wave speed increases with wavelength.
  26. 26. - As waves reach the shallow water near a shoreline, energy is lost due to friction against the seafloor. This slows the wave - Incoming wave crests catch up with slower crests, decreasing the wavelength. - Waves get higher, steeper, and unstable, causing the crests to collapse. - Collapsing wave crests = breakers. Science of Surf
  27. 27. TIDES = periodic rise and fall of sea level · High Tide = highest level · Low Tide = lowest level · Tidal Cycles (High Tide Low Tide High Tide) usually = 24 hrs 50 mins -Diurnal: 1 high tide, 1 low tide every day -Semidiurnal: 2 high tides, 2 low tides every day (this is what we have in NC) -Mixed: 1 high, 1 low, 1 semi-high, 1 semi-low every day
  28. 28. Causes of Tides: Discovery EdTides Brainpop Tides -Gravitational Pull of the Moon and the Sun -Spring Tide = High tide is highest, low tide is lowest. -Neap Tide = High tide is lower than usual, low tide higher than usual. Which is bigger - Solar or Lunar tides? Why?? -Moon is closer, so it has more gravitational pull
  29. 29. Warm-up Quiz 1) What are the two things that cause tides? 2) In an ocean wave, the ______ moves forward, and the _____ moves in a circle. 3) What is a collapsing wave called? 4) What happens to the wave speed when the wavelength increases? 5) What kind of tidal cycle has 2 high tides and 2 low tides every day?
  30. 30. Ocean Currents- Discovery Ed Brainpop Ocean Currents OCEAN CURRENTS CURRENT = movement of a section of water - Density Current = controlled by density. Move very slowly. - Surface Current = controlled by wind. Move very quickly. -Only affect the top few hundred meters of water - Continents deflect some currents so that they join other currents, causing a circular current, called a gyre. - 5 Major Gyres: North & South Pacific, North & South Atlantic, and Indian Ocean - In the Northern Hemisphere, the gyres circulate in a clockwise direction. -In the Southern Hemisphere, the gyres circulate counterclockwise.
  31. 31. Currents flow westward near the equator. When they hit land, they are deflected toward the poles. This carries warm water to colder regions of the world. When it gets to the polar regions, the water cools and is deflected back toward the equator on the other side of the ocean.
  32. 32. UPWELLING · Water not only moves horizontally (currents) but it also moves vertically. · UPWELLING = upward motion of ocean water · Cold water flows upward to replace warm surface water blown out to sea by offshore winds. · They mainly occur on western coasts. · Rich in nutrients, thus supporting lots of marine life.
  33. 33. BEACHES Wave movement toward the shore often builds up a strip of sediment at the coastline called a beach. Beaches are composed of whatever sediment is available, but most beaches are composed of sand.
  34. 34. Wave Impact Breaking waves against land causes cracks and crevaces to open in cliffs. Water is forced into these displacing air. Air expands and disloge rock fragments & extends features.
  35. 35. Abrasion Sawing and grinding action of rock fragments in water.
  36. 36. Wave Refraction • Bending of waves affecting distribution of energy along the shore. • Influences erosion, sediment transfer & deposition take place • Concentrated at headlands
  37. 37. Longshore Transport • Current that flows parallel to the shore and moves large amounts of sediment. • Caused by bending of waves.
  39. 39. • During storms waves can be much more powerful than normal. Created by L. Zimmerman
  40. 40. During these times the beach tends to erode more and the sand is carried back into the ocean. There it is usually deposited as underwater bars parallel to the shore. Created by L. Zimmerman
  41. 41. Wave-Cut Cliffs Cutting action of the surf against the base of coastal land
  42. 42. Platforms Flat, bench like surface is left from cutting waves.
  43. 43. Sea Arches Surf wears away softer rock & cave forms. When two caves connect, a sea arch is formed.
  44. 44. Sea Stack Sea arch falls into the ocean leaving isolated piece.
  46. 46. Spit Elongated ridge of sand that projects from land into the mouth of an adjacent bay
  47. 47. Bar Form across a bay where currents are weak.
  48. 48. Tombolo Ridge of sand that connects an island to the mainland or to another island
  49. 49. If these sand bars rise above the average sea level winds will help to pile up sediment. When vegetation begins to grow and stabilize the offshore sediment pile, a barrier island is created. Created by L. Zimmerman
  50. 50. Hatteras – Ocracoke Island, NC Barrier Island Atlantic Ocean – Sea Side Pamlico Sound (Land Side) Created by L. Zimmerman
  51. 51. Barrier Island Narrow sandbars parallel to but separated from the coast by 3-30 km offshore (300 on US coast in NC, MA, TX, SC)
  53. 53. Groin Barrier built at a right angle to shore to keep sand in place
  54. 54. Breakwall Barrier built perpendicular to the shore to stop incoming waves from damaging shore.
  55. 55. Seawall Barrier built parallel to the shore to stop incoming waves from damaging shore.
  56. 56. Seawalls
  57. 57. Pros & Cons to groins, breakwaters & seawalls • PRO –Protect shoreline & boats from wave action impact & erosion • Con –Temporary structure –Interfere with natural process of erosion & deposition –More structures must be built
  58. 58. The Barrier Islands on the Outer Banks