2. Most bathymetric maps now are made from satellite images of the sea surface. The sea surface reflects what the topography is on the bottom of the ocean.
3. How are the features different than on land? Mountains longer Canyons deeper Valleys wider and flatter Why is this so?
4. Erosion only along shores and steep slopes Salt water dissolves certain materials Showers of sediment fall from the surface
5. The Continental Margin What are they referring to in the book when they mention continental margins? East coast passive and West coast active Passive has four distinct regions Continental shelf Shelf break Slope Rise
8. Active continental margins the slope continues into a deep ocean trench Shelf widths vary from 40 miles to 930 miles in length Note the width of shelves throughout the world on and globe Continental shelves are part of the continent and have been exposed over time
9. Forces that influence the self Florida has strong currents close to shore Continental Shelf Break is where abrupt change is slope (i.e. continent drops off) Continental Slope is where the shelf extends to the ocean West Coast of South America the slope drops 26,000 ft into a deep trench Submarine Canyons created from the rivers of the past Examples are Monterey and Carmel Canyons off the CA coast Canyons created by turbidity currents
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11. How are abyssal plains and hills formed? Sediment deposits & waves of mud created by currents Abyssal Plains are flat areas How are abyssal hills formed? Volcanic action (less than 1000 m) 80% of Pacific floor covered with abyssal hills
12. Seamounts form over active hot spots and sometimes become islands Seamounts have steeper sides than hills Seamounts provide base for corals to grow Corals need warm and sun lit waters See the following slide for examples: Fringing Reef Barrier Reef Atoll
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14. Guyots Flat topped seamounts (1000 -1700 m) Common in Pacific Ocean Evidence that were surface features at one time (i.e. coral remains) Also submerged from rising sea levels
15. The Ridges and Rises Where do these occur? Mountain ranges run through every ocean of the world (40,000 miles) Ridge systems (3500-7000 ft) Ridges are steep Rises are more gentle slopes Rift Valleys are 1500 to 5000 ft deep and run along crest Volcanically very active
16. Where do trenches occur? Convergent plate boundaries Mainly in the Pacific ocean Island Arcs Trenches located on the seaward side of volcanic island chains
18. The Mariana Trench is 11,033 meters (36,201 feet), (6033.5) fathoms deep. The Pressure at the deepest part of the Mariana Trench is over 8 tons per square inch.
19. Video on ocean floor exploration http://www.youtube.com/watch?v=KOG-iAiDiko Google Earth 5 http://www.researchchannel.org/prog/displayevent.aspx?fID=572&rID=21523 UWA Neptune project
21. How is sediment they measured? Particle size, location, origin, and chemistry Samples dried and shaken through a series of sieves Well-sorted sediment in one sieve Poorly sorted sediment in several layers of the sieve
22. Do coastal areas usually have well or poorly sorted sediment? Coastal areas usually have poorly sorted particles dropping out at mouth of the rivers and finer particles settling farther away from the shore Open ocean sediment size determines whether settled out in a few days or 125 years Differently charged particles can attract and sink faster
23. Animals package inorganic remains into tests and expel as fecal pelletsSource: http://marinebio.org/Oceans/Deep/
24. Location of Sediments Classified as either neritic (coast) or pelagic (sea) Neritic found around margins and islands Materials are transported by what? Rivers and erosion from land 15 billion metric tons of sediment carried by oceans each year
25. Rivers of Asia contribute one-quarter of worlds marine sediment What does this tell you? What lies down current from Asia? Pelagic sediment is well or poorly sorted?
26. What are the sources? Pre-existing rocks, marine organisms, seawater, or space Pre-existing rocks are lithogenous (stone) or terrigenous (land) Volcanoes an important source of lithogenous material
27. Rocks from land are transported how? Water, wind, ice and gravity Most lithogenous materials have high amounts of quartz Quartz is resistant to weather and chemical degredation Found long distances from source Lithogenous dominant material in neriticsediment
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29. Abyssal Clay Deep sea floor lithogenous material referred to as Abyssal Clay 70% material of clay to be classified as Abyssal Clay Does this material accumulate at a fast or slow rate? Often rich in iron that oxidizes in water = red clay
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31. Biogenous sediments come from what? Organisms such as shell, coral and skeletal material Pelagic biogenous material shell, tests, or single-celled organisms 30% biogenous material referred to as calcareous or siliceous ooze What are the sources for each type of ooze? Calcareous = shells, coral, tests, coccolithophores (plant-like organisms), pteropods (snails), etc.
32. Dominant ooze is calcareous Dissolves quickly in cool, deep water which is more acidic This layer of water is called the lysocline layer Below 20% layer is called carbonate compensation depth (CCD) At 14,000 to 15,000 ft with exception of Pacific equatorial water where deeper
33. Siliceous = tests, single-celled diatoms, and radiolaria Dissolves in warm shallow waters Oceans undersaturated with siliceous material 90 % is dissolved before preserved on the bottom of ocean Sediments derived from water called Hydrogeous Produced by chemical precipitate of minerals in water
35. What minerals incorporated into nodules? Includes: manganese, iron, copper, cobalt, and nickel Accumulate 1-200 mm per million years Slower than coral! 2-3 cm per year Nodules must be able to react chemically with sea water, if covered stop growing. Therefore found in areas of rapid bottom currents High rates in central Pacific oceans
36. Cosmogeous sediment derived from space 10 % of particles that reach earth enter atmosphere, rest burns up Tear drop shaped from partial burning as enter atmosphere
37. Sampling Sediment by:Dredges (basket dragged), grab samplers (spring loaded), and corers (pipe with sharp edge) used
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39. Under Water Robots or ROVs 1970’s submersibles used Eight hours for 4 hours of target depth time Cost is $25,000 per day Remotely Operated Vehicles (ROV) tethered to surface vessel Use, video, cameras, sensors, mechanical hands, sonar, etc. Jason an example of ROV by Woodshole 3000 lbs and can go up to 20,000 ft deep
40. Autonomous Underwater Vehicles (AUV) Independent with sensors – more mobile Acoustic link Small (50 lbs) and specialized capabilities Navy has specialized AUSS (Advanced Unmanned Search System) 2800 lbs Follows predetermined search pattern emitting sonar images of surface
41. What are the largest amounts of materials mined for in oceans? Sand and gravel 1.2 metric tons per year 800 billion tons in reserve U.S. lead in sand mining Phosphorite used for phosphate fertilizers is found in shallow waters Fl, CA, NC, Mexico, Peru, Australia, Japan Sulphur found in Gulf of Mexico and Mediterranean Sea Coal in Japan’s waters Oil and gas 95% of all resources extracted from seas
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43. Why is cobalt so important? Cobalt is particularly important due to use in tools and aircraft engines 16 million tons of nodules accumulate each year Mining nodules not as productive as hoped
44. Gas HydratesWhy important? Energy source, climate change source, and contribute to coastal slumping along margins, and sea floor stability Create weak zones along SE coast S.C. and N.C. area of 1300 trillion cubic feet of methane gas Stored hydrate gas 3000 times what in atmosphere
45. Mining Laws and Treaties Why do we need them? Valuable nodules United Nations Convention on the Law of the Sea Treaty to regulate deep sea mining Quantities limited and profits shared Overseen by UN company 1982 U.S. and other industrialized nations did not sign 1998 Year Of The Ocean brought hope to signing of treaty High cost of mining and low international markets driving the need to sign treaty
