1. 3 What does the bottom of the ocean look like? OR What is the topography or bathymetry of the ocean floor?

2. 3 Topography of the Ocean Floor echo soundings (1920’s) ocean was not deepest in the center deepest part of the ocean lie near its edges

3. 3 Fig 4-2a, p.67

4. 3 Fig 4-3a, p.67

5. 3 Fig. 4-2b, p. 67 An echo sounder trace. A sound pulse from a ship is reflected off the seabed and returns to the ship. Transit time provides a measure of depth. For example, it takes about 2 seconds for a sound pulse to strike the bottom and return to the ship when the water depth is 1,500 meters (4,900 feet). Bottom contours are revealed as the ship sails a steady course. In this trace, the horizontal axis represents the course of the ship, and the vertical axis represents the water depth. The ship has sailed over a small submarine canyon.

6. 3 Fig. 4-4c, p. 68 Ridges/trenches in South Atlantic Sea Floor

7. 3 Fig nft Bathymetry can tell you where things are: Oceanic ridge system

8. 3 BATHYMETRY – OCEAN FLOOR CONTOURS Fig 4-5, p.69

9. 3 Fnft: The major plates of the earth's crusts Courtesy of Reto Stockli, NASA Earth Observatory

10. 3 Fig. 4-17a, p. 78 Atlantic Ocean

11. 3 Fnft: Some large-scale features of the North Atlantic seafloor Courtesy National Geophysical Data Center/NOAA

12. 3 Fig. 4-11, p. 74 Folded ridges of sediment cover the ocean floor west of Oregon

13. 3 Topography of the Ocean Floor REMEMBER: deepest part of the ocean lie near its edges

14. 3 fnft

15. 3 Topography of the Ocean Floor Submerged outer edge of the continents are called continental margins Deep-sea floor beyond these is called the ocean basin

16. 3 Fig 4-6, p.70

17. 3 Fig. 4-25, p. 84

18. 3 Fig 4-9, p.72

19. 3 Fig 4-10, p.73 Florida coast

20. 3 but There are 2 sides to every…OCEAN!

21. 3 Fig 4-8, p.71

22. 3 2 types of “margins” PASSIVE MARGIN: Continental margins that face diverging plates. These do not coincide with plate boundaries. Little or no activity. Typically associated with the Atlantic. ACTIVE MARGIN: Continental margins that face converging plates. These coincide w/plate boundaries. A lot of activity (earthquake/volcano). Typically associated with the Pacific.

23. 3 Continental Margins Passive margins – –continental margins not located on plate boundaries –Atlantic-type margins

24. 3 Continental Margins Active margins- –continental margins on the edge of convergent or transform plate boundaries –Pacific-type margins

25. 3 Fig 4-8, p.71

26. 3 Fig 4-9, p.72

27. 3 Continental Margins (Shelves) Width of Continental Shelf is determined by : proximity to a plate boundary (active margins have narrow shelves while passive margins have broad shelves)

28. 3 Continental Margins (Shelves) Continental Shelves –Shallow, submerged extension of a continent –broad, gently sloping –7.4% of earths Ocean area

29. 3 Fig nft

30. 3 Continental (Passive) Margins Shelf break – –transition between the continental shelf and the continental slope There are also changes from the continental slope (edge of shelf) to the continental rise (ends at edge of ocean floor).

31. 3 Continental Margins Continental Slopes –Steeper than the shelf –end at the deep ocean

32. 3 Fig 4-9, p.72

33. 3

34. 3 Continental Margins Continental rises –at the base of continental slope –covered by a blanket of accumulated sediment –gradual slope

35. 3 Continental Margins Submarine Canyons –cut into the continental shelf and slope –formed by turbidity currents (avalanche-like sediment movements)

36. 3 F 4.12

37. 3 Fig 4-13, p.75 Submarine Canyon Off of The coast Of New Jersey

38. 3

39. 3 Fig. 4-17b, p. 78 Mid-Atlantic Ridge between Florida and western Africa  Canyon in middle of ridge

40. 3 Ocean Basin thick layer of sediment (up to 5 km or 3mi thick) covering basaltic rocks Make up more than ½ of the earth’s surface

41. 3 Ocean Basin Oceanic ridges –Underwater mountain chain –an active spreading center –offset at regular intervals by transform faults

42. 3 Fig nft WHERE THE RIDGES ARE!

43. 3 Midoceanic Ridge Province consists of a continuous submarine mountain range. It covers about one third of the ocean floor. It extends for about 60,000 km around the Earth.

44. 3 Examples of what “exists” on the Ocean Floor Hydrothermal Vents SeaMounts Guyots Abyssal Hills Abysall Plains Trenches Island Arcs (seen above “land”)

45. 3 Ocean Basin Seamounts –Inactive volcanoes that do not rise above the surface of the ocean –They are tall with steep slopes

46. 3 Ocean Basin Guyots –Flat-topped seamounts that were eroded by wave action Abyssal Hills –abundant, small sediment-covered extinct volcanoes

47. 3 Fig. 4-23a, p. 82 guyots (G) and seamounts

48. 3 Ocean Basin Island Arcs –Curving chains of volcanic islands and seamounts found paralleling the edge of trenches

49. 3 Fig 4-23, p.76

50. 3 Coral Reefs? All of these different land/(under)water formations can yield MANY different types of coral reefs (a very diverse, valuable, marine community) too!

51. 3 Fnft

52. 3

53. 3

54. 3

55. 3 Ocean Basin Abyssal Plains –Flat, featureless, sediment-covered ocean floor Trenches –Arc-shaped depression in the deep seafloor –a converging oceanic plate is subducted

56. 3 Deep Ocean Province is between the continental margins and the midoceanic ridge. It includes a variety of features from mountainous to flat plains: –Abyssal plains –Abyssal hills –Seamounts –Deep sea trenches

57. 3 Ocean Basin Hydrothermal vents –average temp is about 8-16 o C (46-61 o F) much warmer than the typical 3-4 o C (37- 39 o F) –support a unique community of organisms that depend on bacteria

58. 3 Cross-section of a ridge axis and the plumbing connected to a vent chimney

59. 3 Fig 4-20, p.80

60. 3 Sidescan sonar image overlaid onto multibeam bathymetry

61. 3 Approximate locations of confirmed hydrothermal vents and cold seeps

62. 3 Red-plumed tube worms Courtesy of Monika Bright, University of Vienna, hydrothermalvent.com

63. 3 A black smoker on the Galápagos Rift Zone. Courtesy of UCSB, University S. Carolina, WHOI/NOAA

64. 3 Fig 4-19, p.79