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The Ocean Floor

The Ocean Floor. Chapter 13 Section 2. How Scientists Study the Ocean Floor. Sonar used from the ocean surface Satellite: Used in space Seasat Geosat. Sonar. So und N avigation a nd R anging Scientists send sound waves to the bottom of the ocean by ship .

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The Ocean Floor

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  1. The Ocean Floor Chapter 13 Section 2

  2. How Scientists Study the Ocean Floor • Sonar • used from the ocean surface • Satellite: Used in space • Seasat • Geosat

  3. Sonar • Sound Navigation and Ranging • Scientists send sound waves to the bottom of the ocean by ship. • The sound waves bounce off the ocean floor and return to the ship. • The deeper the ocean, the longer it takes for the sound waves to return.

  4. How Scientists Study the Ocean Floor • Sonar • used from the ocean surface • Satellite: Used in space • Seasat • Geosat

  5. SONAR-FYI • Measuring Water Depth: • Today's oceanographers use sonar instruments to generate a sound signal that is bounced or "echoed" off the sea floor and then recorded on board the ship. • The speed of sound in water is 1,500 m per second, four times faster than the speed of sound in air.

  6. SONAR-FYI • Measuring Water Depth: • By carefully measuring the round-trip time of the sound waves and taking into account the variables of temperature and salinity, the depth of the water and the distance to another object can be measured accurately. • Sonar is also how bats fly since they are blind—hence the idiom “blind as a bat.”

  7. Seasat: launched in 1978 & focused on the ocean • Seasat sends images to Earth that measure direction and speed of ocean currents. space.skyrocket.de/doc_sdat/seasat. http://rst.gsfc.nasa.gov/Sect14/workshop2+.jpg

  8. Geosat- Navy Satellite • Once a top-secret Military satellite • Measures the slightest changes in the height of the ocean’s surface • Different underwater features affect the height of the water above them. • Thus, measuring surface height allows scientists to map the ocean floor & do it faster than with sonar. http://rst.gsfc.nasa.gov/Intro/Part2_1b.html

  9. A Map of the Ocean Floor Produced by Geosat http://rst.gsfc.nasa.gov/Intro/Part2_1b.html

  10. How Does Geosat Work? Source: http://rst.gsfc.nasa.gov/Intro/Part2_1b.html

  11. Continental Margin: made of continental crust based on depth & changes in slope Made of: Continental shelf Continental slope Continental rise Deep-ocean basin: made of oceanic crust Form near tectonic plate boundaries Abyssal Plain Mid-ocean ridge Rift valley Ocean trench Seamounts The Ocean Floor has two parts:

  12. Twenty Thousand Leagues Under the Sea, by Jules Verne 1870 • His book revived interest in undersea exploration • Inspired engineers to solve the problems with submarines at that time, which allowed scientists to reach deeper into the ocean

  13. Continental Margin Continental shelf A Continental slope B Continental rise C Deep-ocean basin Abyssal Plain E Mid-ocean ridge F Rift valley F Ocean trench H Seamounts D/G A B A C F G E D H

  14. Continental Shelf • Begins at the shoreline • Continues until the ocean floor starts to slope • Depth can reach about 200 meters

  15. Continental Slope: • Begins at edge of continental shelf • Continues down to the flat part of the ocean floor • Ranges between 200 meters to about 4000 meters

  16. Continental Rise • It is the base of continental slope. • Made of large piles of sediment

  17. Now you label 1. 2. 3.

  18. Abyssal Plain • Large, wide, flat area of the ocean floor • Covered in mud & remains of tiny marine organisms • Average depth 4000 meters Abyssal Plain

  19. Sea Creatures of the Abyssal Plain

  20. Mid-Ocean Ridge • Underwater mountain ranges • Form where tectonic plates pull apart creating a rift zone • Rising magma between the plates creates the ridge

  21. Mid-Ocean Ridge

  22. Rift Valley: the zone b/w the plates • As the mid-ocean ridges build up, a rift valley forms b/w them in the rift zone. • Rift valley: • can be 15 to 30 miles (24 to 48 kilometers) wide • new oceanic crust is being made, which means lots of seismic activity is happening • Hydrothermal ventswere discovered there.

  23. Hydrothermal Vents www.public.asu.edu/~booksh/apps.htm www.naturalhistorymag.com/0904/0904_feature.html

  24. Rift Valley

  25. Animals of the hydrothermal community: www.biosbcc.net/.../04benthon/dsvents.htm http://newsimg.bbc.co.uk/media/images/41417000/jpg/_41417766_yeti2_ap_203.jpg

  26. Ocean Trench: • Huge cracks in the deep-ocean basin. • Created by oceanic plate pushing beneath continental plate or another oceanic plate • Deep-sea trenches are the deepest parts of the ocean.

  27. The deepest one, the Marianas Trench in the South Pacific Ocean, is more than 35,000 feet (10,668 meters), or almost 6.6 miles (10.6 kilometers) deep. A Navy-owned submarine, the Trieste, still holds the record for diving to the bottom of the deepest part of the Marianas Trench, the Challenger Deep, on January 23,1960. www.worsleyschool.net/.../marianas/trench.html

  28. Seamounts: individual mountains of volcanic material • Formed when magma pushes its way through or between tectonic plates • If seamounts build up above sea level (above the height of the ocean’s surface) they can become volcanic islands • Example: Hawaiian Islands • Seamounts are usually 25 miles (40 kilometers) in diameter and can be 10,000 to 15,000 feet (3000 to 4500 meters) tall.

  29. Seamounts • Less than 0.1 percent of the world's seamounts have been explored to learn what species live on them, but many of the species that have been found so far are new to science.

  30. Alvin, the world's first deep-sea submersible; 7m long; seats 3 Used to discover the hydrothermal vents—found in 1977 off of the Galapagos islands, recover a lost hydrogen bomb, sunken ships, etc. Alvin can reach a maximum depth of about 4,000 meters (people can make it about 33 meters without harm). Piloted Underwater Vessels http://coexploration.org/bbsr/classroombats/assets/images/Alvin.jpg

  31. Alvin at work http://coexploration.org/bbsr/classroombats/assets/images/Alvin.jpg

  32. Shinkai 6500- Japan • Shinkai 6500, a Japanese research submarine built in 1989, can work at depths down to 6,400 m. • World's deepest-diving manned research submarine.

  33. http://pubs.usgs.gov/gip/dynamic/graphics/shinkai.gif

  34. Deep Flight: an underwater airplane • Moves through water like an airplane moves through air • Future models of Deep Flight will be able to take pilots 11,000m deep. http://www.membrana.ru/images/articles/1048860407-0.jpeg

  35. Robotic Vessels: Jason II and Medea • Piloted vessels expensive & dangerous • So scientists use robotic vessels such as Jason & Medea • Can withstand pressures greater than those found in the deepest part of the ocean

  36. Robotic Vessels: Jason II and Medea • Piloted by a person at the surface • Medea is attached to Jason by a tether (a rope-like connection) & explores above the sea floor. • Dr. Robert Ballard, the "Indiana Jones" of the sea, is not only famous for discovering the sunken remains of the R.M.S. Titanic. He is also founder of the JASON project, which is a highly acclaimed year-long curriculum that educates millions of students through scientific discovery.

  37. Jason: a $2.5 million robotic vessel Medea: www.onr.navy.mil/.../vessels/submersibles3.htm Jason: www.whoi.edu/.../jason/userman_video.html

  38. Quiz • 1. What type of ocean feature creates the Hawaiian Islands? • 2. Where in the ocean is pressure the greatest or the most intense? • 3. What is sonar? • 4. What is an underwater mountain range? • 5. What is an underwater volcano? • 6. What is the large, wide feature of the ocean that is covered by mud and remains of marine organisms? • 7. What is a rift valley? • 8. What is a huge crack in the ocean floor called? • 9. What is the continental rise? What makes it? • 10. What makes up the continental margin? • 11. What makes up the deep ocean basin? • 12. Where do tectonic plates pull apart or move away from each other? • 13. What is the deepest part of the ocean?

  39. Answers • 1. What type of ocean feature creates the Hawaiian Islands? Volcanic seamounts • 2. Where in the ocean is pressure the greatest or the most intense? At the bottom in the ocean trenches • 3. What is sonar? Using sound waves to map things • 4. What is an underwater mountain range? Mid-ocean ridge • 5. What is an underwater volcano? seamount • 6. What is the large, wide feature of the ocean that is covered by mud and remains of marine organisms? Abyssal plain • 7. What is a rift valley? The area b/w the mountains of a mid-ocean ridge • 8. What is a huge crack in the ocean floor called? Ocean trench • 9. What is the continental rise? What makes it? The base of the continental slope; sediment washed down the slope • 10. What makes up the continental margin? Continental shelf, continental slope, and continental rise • 11. What makes up the deep ocean basin? Abyssal plain, mid-ocean ridges, rift valleys, seamounts, & ocean trenches • 12. Where do tectonic plates pull apart or move away from each other? Mid-ocean ridges • 13. Want is the deepest part of the ocean? Ocean trenches

  40. Name the features shown at W, X, and Z:

  41. Label the areas of the continental margin:

  42. Label the areas of the ocean floor: • W = continental shelf • X = continental slope • Y = continental rise • Z = abyssal plain

  43. Summary: The Ocean Floor • The continents lie on the continental plates. The edges of these plates are under water, and they form the continental shelves. • These shelves slope outward very gently towards the ocean depths. In some places these shelves go out a long way, up to 900 miles. • In other places the shelves are much narrower. These shelves are fairly smooth because debris from the land is falling onto them from the water. • This debris contains nutrients washed down from the land, and these nutrients, plus the shallow water, contribute to the abundance of life forms near the continents. • Where the continental shelves end, there is a steep drop downwards. This is called the continental slope. • It plunges down into the dark, cold waters of the ocean. At the bottom of the continental slope there is a an area that slopes gradually downward to blend into the abyssal plain. This is the bottom of the ocean as we think of it.

  44. Summary: The Ocean Floor • The ocean floor seems like a different world. There is no sun light down here. The water is very cold. The pressure of the weight of miles of water above this area would easily crush a submarine. • Tiny flecks of material from the sunlit world float downward and eventually settle on the bottom. There is almost nothing to eat, and the animals that live here are few and far between. There are many different kinds of animals, but they are small and widely scattered. They are able to survive on very little. • However, it is not all silence and darkness here. The earth's crust is thinnest in the ocean basins, and volcanic eruptions are part of this environment.  Here and there isolated peaks called sea mounts rise above the flat abyssal plain. • However, the most active part of deep ocean geology occurs in the deep sea trenches, where the ocean floor is spreading apart. Lava comes up through the fissures, building up mountains and deep sea vents, called smokers. The constantly up-welling lava pushes the sea floor away from the trenches and out towards the continents. When the sea floor reaches the continental plates, it subducts, or slides underneath them, carrying the cold rocky floor back into the hot mantle of the earth.

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