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

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What does the bottom of the ocean look like? OR What is the topography or bathymetry of the ocean floor? Topography of the Ocean Floor echo soundings (1920 s) ocean ... – PowerPoint PPT presentation

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Title: What does the bottom of the ocean look like? OR What is the topography or bathymetry of the ocean floor?


1
What does the bottom of the ocean look
like?ORWhat is the topography or bathymetry
of the ocean floor?
2
Topography of the Ocean Floor
  • echo soundings (1920s)
  • ocean was not deepest in the center
  • deepest part of the ocean lie near its edges

3
Fig 4-2a, p.67
4
Fig 4-3a, p.67
5
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.
Fig. 4-2b, p. 67
6
Ridges/trenches in South Atlantic Sea Floor
Fig. 4-4c, p. 68
7
Bathymetry can tell you where things are Oceanic
ridge system
Fig nft
8
BATHYMETRY OCEAN FLOOR CONTOURS
Fig 4-5, p.69
9
Fnft The major plates of the earth's crusts
Courtesy of Reto Stockli, NASA Earth Observatory
10
Atlantic Ocean
Fig. 4-17a, p. 78
11
Fnft Some large-scale features of the North
Atlantic seafloor
Courtesy National Geophysical Data Center/NOAA
12
Folded ridges of sediment cover the ocean floor
west of Oregon
Fig. 4-11, p. 74
13
Topography of the Ocean Floor
  • REMEMBER
  • deepest part of the ocean lie near its edges

14
fnft
15
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
Fig 4-6, p.70
17
Fig. 4-25, p. 84
18
Fig 4-9, p.72
19
Florida coast
Fig 4-10, p.73
20
but
  • There are 2 sides to everyOCEAN!

21
Fig 4-8, p.71
22
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
Continental Margins
  • Passive margins
  • continental margins not located on plate
    boundaries
  • Atlantic-type margins

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

25
Fig 4-8, p.71
26
Fig 4-9, p.72
27
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
Continental Margins (Shelves)
  • Continental Shelves
  • Shallow, submerged extension of a continent
  • broad, gently sloping
  • 7.4 of earths Ocean area

29
Fig nft
30
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
Continental Margins
  • Continental Slopes
  • Steeper than the shelf
  • end at the deep ocean

32
Fig 4-9, p.72
33
Fig 4-9, p.72
34
Continental Margins
  • Continental rises
  • at the base of continental slope
  • covered by a blanket of accumulated sediment
  • gradual slope

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

36
F 4.12
37
Submarine Canyon Off of The coast Of New Jersey
Fig 4-13, p.75
38
(No Transcript)
39
Mid-Atlantic Ridge between Florida and western
Africa
  • Canyon in middle
  • of ridge

Fig. 4-17b, p. 78
40
Ocean Basin
  • thick layer of sediment (up to 5 km or 3mi thick)
    covering basaltic rocks
  • Make up more than ½ of the earths surface

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

42
WHERE THE RIDGES ARE!
Fig nft
43
  • 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
Examples of what exists on the Ocean Floor
  • Hydrothermal Vents
  • SeaMounts
  • Guyots
  • Abyssal Hills
  • Abysall Plains
  • Trenches
  • Island Arcs (seen above land)

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

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

47
guyots (G) and seamounts
Fig. 4-23a, p. 82
48
Ocean Basin
  • Island Arcs
  • Curving chains of volcanic islands and seamounts
    found paralleling the edge of trenches

49
Fig 4-23, p.76
50
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
Fnft
52
Fnft
53
Fnft
54
Fnft
55
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
  • 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
Ocean Basin
  • Hydrothermal vents
  • average temp is about 8-16oC (46-61oF) much
    warmer than the typical 3-4oC (37-39oF)
  • support a unique community of organisms that
    depend on bacteria

58
Cross-section of a ridge axis and the plumbing
connected to a vent chimney
59
Fig 4-20, p.80
60
Sidescan sonar image overlaid onto multibeam
bathymetry
61
Approximate locations of confirmed hydrothermal
vents and cold seeps
62
Red-plumed tube worms
Courtesy of Monika Bright, University of Vienna,
hydrothermalvent.com
63
A black smoker on the Galápagos Rift Zone.
Courtesy of UCSB, University S. Carolina,
WHOI/NOAA
64
Fig 4-19, p.79
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