2. The Sea Floor and Its Sediments An Introduction to the World’s Oceans Sverdrup et al. - Chapter Four - 8th Ed.

3. Bathymetry How deep is that water anyway? Sounding techniques Line or cable – “rock-on-a-rope” Echo Sounding Multibeam Systems – swath image Satellite Altimetry

4. Measuring the Depths – Bathymetry a study in technological evolution. Methods for measuring depths: Hand line and wire marked with fathoms, with a lead weight on the end – “Rock on a Rope” Posidonius 85 B.C. made soundings fathoms = 6 feet (arm span) greased piano wire & cannonball Echo sounder, or depth recorder Meteor – 1925 German vessel – echo sounding GLORIA – sidescan sonar “fish” - multibeam Laser airborne depth sounder (LADS) limited depth – turbidity matters Satellites Gravity bumps and valleys

5. Historic “Soundings” Posidonius – 85B.C. – “rock on a rope” – 2km Sir James Clark Ross – 1818 – 4.893 km HMS Challenger – 1870’s – “steam powered” rock on a rope - 492 bottom soundings – confirmed Maury’s discovery of the Mid-Atlantic Ridge

6. Echo Sounding and its disadvantage

7. Fig. 4.1

9. Box Fig. 1.

10. Box Fig. 2, pg. 103

11. U. S. Navy satellite Geosat

12. How a “Gravity” survey works.

13. Fig. 4.3

14. Bathymetry of the Sea Floor Continental margin Continental shelf Submarine canyons Continental shelf break Continental slope Continental rise Turbidites Abyssal fans

15. Bathymetry of the Sea Floor Ocean basin floor Abyssal plain Abyssal hills Seamounts Guyots Fringing reefs Barrier reefs Ridges, rises, and trenches Plate tectonics

18. Fig. 4.4

19. Fig. 4.5 Continental Shelves

20. Passive Continental Margins Continental shelf, slope, rise The Continental Rise Types of Deposition From turbidity currents From contour currents Abyssal plains

21. Florida continental shelf Shelf Slope Break Abyssal Plain Rise

22. Active Continental Margins On land- earthquakes, young mountain belt, volcanoes Continental shelf, continental slope, oceanic trench Oceanic Trenches Earthquakes of the Benioff seismic Zones Volcanoes Low Heat Flow Negative Gravity Anomalies

23. Active continental margin along Oregon Coast. Folded sea floor sediments being scraped from the Juan de Fuca Plate as it subducts beneath the N. American Plate

24. Fig. 4.6

25. Fig. 4.7 “Typical” Passive Margin

27. Submarine Canyons Abyssal Fans (at base like alluvial fans) Down-canyon movement of sand Bottom Currents (tides?) River erosion (during ice age shelf exposure) Turbidity Currents Graded bedding Shallow water fossils

28. Submarine Canyon

29. Fig. 4.8

30. Fig. 4.10

32. Turbidity current off Jamaica

33. Field Notes: Giant Hawaiian Landslides Giant landslides Blocks or rock: 30 km x 5 km x 2 km Frequency of occurrence Several per million years Posed important hazard Scientific research Identifying the causes Predicting the next giant landslide

35. Fig. 4.11

36. Fig. 4.12

37. Box Fig. 2

38. Fig. 4.14

39. Fig. 4.13

40. Fig. 4.15

41. Fig. 4.16

42. Sediments Particle size Classification Horizontal transport and sorting Location Classification: neritic or pelagic Rates of deposit Processes and variability Source and chemistry Lithogenous sediments Biogenous sediments Hydrogenous sediments Cosmogenous sediments

44. Fig. 4.17

45. Fig. 4.18

47. Classifying Sediment by Source Terrigenous – composed of fragments of pre-existing rock material Terrigenous – composed of fragments of pre-existing rock material Neritic - at the coast Neritic - at the coast Biogenous – composed of hard remains of once-living organisms Biogenous – composed of hard remains of once-living organisms Pelagic – open water Pelagic – open water Hydrogenous - formed when dissolved materials come out of solution (precipitate) Hydrogenous - formed when dissolved materials come out of solution (precipitate) Authigenic – formed in place Authigenic – formed in place Cosmogenous Sediment – outer space derived Cosmogenous Sediment – outer space derived Sediment Mixtures – mostly the case Sediment Mixtures – mostly the case

48. Origin of terrigenous sediment Forms by: Weathering = breakup of exposed rock Transportation = movement of sediment Deposition = settling and accumulation Sediment-transporting media

49. Terrigenous sediment texture Texture includes: Texture includes: Grain size Grain size Sorting Sorting Rounding Rounding Maturity Maturity

50. Wind blown dust as a source of terrigenous sediment in the Deep Ocean

51. Distribution of terrigenous sediment Terrigenous sediment occurs as: Terrigenous sediment occurs as: Neritic (nearshore) deposits Neritic (nearshore) deposits Beaches Beaches Continental shelves Continental shelves Turbidites Turbidites Glacial-rafted debris Glacial-rafted debris Pelagic (deep ocean floor) deposits Pelagic (deep ocean floor) deposits Abyssal clay Abyssal clay

54. Fig. 4.19

55. Fig. 4.20

56. Fig. 4.21a

57. Fig. 4.21b

58. Fig. 4.21c

59. Demise of the Dinosaurs Example

60. Sediments Patterns of deposit on the sea floor Processes and patterns Climatic variations are recorded in layered sediments Formation of rock - lithification Sedimentary rock Metamorphic rock Sampling methods Dredges, grab samplers, a corer, and acoustic profiling Sediments as historical records Distribution and isotopic composition of skeletal remains

62. Fig. 4.23

63. Fig. 4.24

64. Fig. 4.25a

65. Fig. 4.25b

66. Fig. 4.26

67. Fig. 4.27a,b

68. Fig. 4.27c

69. Fig. 4.27d

70. Fig. 4.27e

71. Seabed Resources Sand and gravel Sand and gravel, calcium oxide, calcium carbonate, tin, iron, platinum, gold, and diamonds (currently mined) Phosphorite Phosphate fertilizer (not currently mined) Sulfur (no longer mined) Coal (currently mined) Oil and gas (currently extracted) Gas hydrates (not mined) Methane and water

72. Fig. 4.28

73. Seabed Resources Manganese nodules Manganese, copper, nickel, and cobalt (not currently mined) Sulfide mineral deposits (not currently mined) Relatively little is known about these deposits to determine their economic importance Laws and treaties 200-mile economic zones International treaties

74. Summary Methods for measuring ocean depth Bathymetric features Continental shelf, slope, and rise Ocean basin floor Seamounts and barrier reef formation Sediment classification Size, location, origin, and chemistry Biogenous sediments Siliceous and calcareous sediments Carbonate compensation depth (CCD) Sediment sampling methods Calcareous biogenous sediment cores Used to study climate change

75. The End