Lecture #5 Week #4 A.K. Morris, Ph.D. Chapter 4 Chapter 4 Seafloor & Ocean Basins Seafloor & Ocean Basins Oceanography Lecture #5 A.K. Morris, Ph.D. 1 We are a species of seafarers We are a species of seafarers 2 We have become very good at We have become very good at “reading reading” the sea surface the sea surface 3 Despite all that we know Despite all that we know historically about the ocean historically about the ocean 4 Seegurke J. Gutt Our knowledge of the seafloor Our knowledge of the seafloor pales in comparison. pales in comparison. 5 Fig. 4.1 No shortage of ways to sample the ocean bottom these days 6
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We are a species of seafarers Chapter 4 Seafloor Ocean Basinsstaff · 2010-09-07 · Lecture #5 Week #4 A.K. Morris, Ph.D. Chapter 4 Seafloor & Ocean Basins Oceanography Lecture #5
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Lecture #5 Week #4
A.K. Morris, Ph.D.
Chapter 4Chapter 4
Seafloor & Ocean BasinsSeafloor & Ocean Basins
OceanographyLecture #5A.K. Morris, Ph.D.
1
We are a species of seafarersWe are a species of seafarers
2
We have become very good at We have become very good at ““readingreading””the sea surfacethe sea surface
3
Despite all that we knowDespite all that we knowhistorically about the oceanhistorically about the ocean
4
Seegurke J. Gutt
Our knowledge of the seafloorOur knowledge of the seafloorpales in comparison.pales in comparison.
5
Fig. 4.1
No shortage of ways to sample the ocean bottom these days
6
Lecture #5 Week #4
A.K. Morris, Ph.D.
Proto‐bathysphere
••Made out of leather and metalMade out of leather and metal••Gaspard SchottGaspard Schott’’ss““Curiosa sive Mirabilia ArtisCuriosa sive Mirabilia Artis”” 16641664
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Historic seafloor MappingHistoric seafloor Mapping• “Heaving the lead”
• Line is “clearly” marked– 2 fathoms from the lead ‐ 2 strips of
leather.
– 3 fa ‐ 3 strips of leather.
– 5 fa‐ a piece of white cloth.
– 7 fa‐ a piece of red cloth.
– 10 fa‐ a piece of leather with a hole in it.
– 13 fa‐ a piece of blue cloth.
– 15 fa‐ same as for 5 fathoms.
– 17 fa‐ same as for 7 fathoms.
– 20 fa‐ small line with 2 knots.
– 25 fa‐ small line with 1 knot.
– 30 fa‐ small line with 3 knots.
– 35 fa‐ small line with 1 knot.
– 40 fa‐ small line with 4 knots.
UGH! UGH! –– dondon’’t forget your t forget your ““clearclear”” markersmarkers 8
•• Actually detected the MidActually detected the Mid‐‐Atlantic ridge, Atlantic ridge, but didnbut didn’’t know what to make of itt know what to make of it
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Matthew Fontaine Maury (1806‐1873)•• Aside: commissioned by the American whaling industry to map Aside: commissioned by the American whaling industry to map
•• Sound waves fired by an air gun from the shipSound waves fired by an air gun from the ship•• Sound echoes off different subSound echoes off different sub--layerslayers•• Returns to detector at different timesReturns to detector at different times
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MultiMulti‐‐channel seismic systems (large scale)channel seismic systems (large scale)
•• Same concept using sound waves fired by an air gunSame concept using sound waves fired by an air gun•• Uses many different frequencies, soUses many different frequencies, so•• Much better resolutionMuch better resolution
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Actual multiActual multi‐‐channel seismic data channel seismic data
•• SideSide--scan sonar is very popular todayscan sonar is very popular today•• FanFan--shaped pulsesshaped pulses•• Works well over relatively flat areasWorks well over relatively flat areas