fig. 4-co, p. 97. fig. 4-1, p. 99 fig. 4-2a, p. 100
TRANSCRIPT
Fig. 4-CO, p. 97
Fig. 4-1, p. 99
Fig. 4-2a, p. 100
Fig. 4-2a, p. 100
Beam of sound waves travels to bottom and is reflected back to ship
Depth = V (T/2)
Fig. 4-2b, p. 100
Fig. 4-2b, p. 100
Sound beam emitted by echo sounder (beam angle is exaggerated)
Measured depth is less than actual depth
Mea
sure
d d
epth
equ
als
tru
e d
epth
Seafloor
Tru
e d
epth
im
med
iate
lyb
enea
th v
esse
l
Fig. 4-2c, p. 100
Fig. 4-3, p. 101
Fig. 4-4a, p. 101
Fig. 4-4b, p. 101
Box 4-1a, p. 102
Box 4-1b, p. 103
Box 4-1b, p. 103
500
1,000
1,500
Dep
th (
m)
2,000 −200
−4002,500 −600 X
(m
)
−8003,000
−5,000 −5,500 −6,000Y (m)
Box 4-1c, p. 103
Box 4-1c, p. 103
49 46.5
49 46.0
Lat
itu
de
49 45.5
−16.5 −16.0 −15.5 −15.0−130 −130
Longitude
−130 −130
Fig. 4-5a, p. 104
Fig. 4-5b, p. 104
GeosatOrbit
h
Sea Surface
Ocean
Seafloor
Crust
Fig. 4-5c, p. 104
Fig. 4-6, p. 105
Fig. 4-6a, p. 105
Fig. 4-6b, p. 105
Fig. 4-6b, p. 105
4,5723,048
Sierra Nevada Rocky Mountains10,00015,000
1,524Appalachian Mountains 5,000
Hei
gh
t in
met
ers
0 0
Hei
gh
t in
fee
t
–1,524 –5,000–3,048 –10,000–4,572 –15,000
Dep
th i
n m
eter
s
–6,096 South America Atlantic Ridge Africa –20,000
Dep
th i
n f
eet0 100 200 300 400 500
Horizontal scale in nautical miles
0 200 400 600 800 926Horizontal scale in kilometers
Vertical x 100
Fig. 4-7, p. 105
Fig. 4-7, p. 105
Earth’s area (hundreds of millions of square kilometers)
Mount Everest 8.85 km (5.5 mi)
Ele
vati
on
(ki
lom
eter
s)
Mean land elevation 840 m (2,760 ft) E
leva
tio
n (
mil
es)
Sea level
Mean depth of sea 3,796 m (12,451 ft)
Dep
th (
kilo
met
ers)
Dep
th (
mil
es)
Mariana Trench ~11 km
% Earth’s area at this elevation or higher
Fig. 4-8, p. 106
Fig. 4-8, p. 106
Continental margin
Deep-ocean basin Continental margin
Submarine canyon profile (cut through continental shelf)Sediment
Continental shelfContinental slope
Continental riseOceanic
ridge Sediment
Continental crust (granitic)
Continental crust (granitic)
Oceanic crust (basaltic)
Oceanic crust (basaltic)Asthenosphere
Fig. 4-9, p. 106
Fig. 4-9, p. 106
Continental mountains 10.3%Oceanic
ridges 22.1%Continental lowlands 18.9%
Ocean basin floors 29.8%
Continental shelves and
slopes 11.4%
Volcanic island arcs, trenches, submarine volcanoes, and hills 3.7%
Continental rise 3.8%
Continental crustOceanic crust
Fig. 4-10, p. 107
Fig. 4-10, p. 107
An active margin
Narrow continental shelfPeru–Chile
Trench
A passive marginPlate
boundaryAndes Mountains
South AmericaBroad continental shelf
Plate boundary
Pacific Ocean South American Plate
Deep basin
Atlantic Ocean
Nazca PlatePlate movement
African Plate
Plate movement
Plate movement
Subduction zone (deep and shallow earthquakes)
Mid-Atlantic Ridge (spreading centers, shallow earthquakes)
Fig. 4-11, p. 108
Fig. 4-11, p. 108
Distance from shore (miles)
0 100 200 300 400 500 600 700
Continental marginContinental
shelf Sea level0 0Shelf break (~140 m, 460 ft)
1 Continental rise1
2
Dep
th (
km)
3 2
Dep
th (
mil
es)
4 Deep-ocean floor5 C
on
tin
enta
l slo
pe
3
0 100 200 300 400 500 600 700 800 900 1,000 1,100 1,200 Vertical exaggeration 50:1. Distance from shore (km)
Sea level04
Dep
th (
km)
0 100 200 300 400 500 600 700 800 900 1,000 1,100 1,200No vertical exaggeration.
(sediment thickness varies)
Fig. 4-12, p. 108
Fig. 4-13, p. 109
Fig. 4-14, p. 109
Fig. 4-15, p. 110
Fig. 4-15, p. 110
Today’s sea level00
Hei
gh
t ab
ove
or
bel
ow
p
rese
nt
sea
leve
l (m
)
Hei
gh
t ab
ove
or
bel
ow
p
rese
nt
sea
leve
l (f
t)
–130 –426
0 50,000 100,000 150,000 200,000 250,000Years before present
Fig. 4-16, p. 111
Fig. 4-16, p. 111
Canyon heads Continental
shelf
Shelf break
Deep-sea fan
Continental slope
Distribution channel
Fig. 4-17, p. 111
Fig. 4-18, p. 112
Fig. 4-19, p. 112
Fig. 4-20, p. 112
Fig. 4-20, p. 112
Feet Meters
14,400 4,390
15,000 4,570
0 1 2 3 4 5 Miles
Depth
15,600 4,760
1 2 3 4 5 6 Kilometers
Fig. 4-21a, p. 114
Fig. 4-21a, p. 114
Mid-Atlantic Ridge
Juan de Fuca Ridge
2.6
East Pacific Rise (Ridge)
15.73.8 5.5
10.72.8
9.59.5
6.41.5
6.4Pacific–Antarctic Ridge
Fig. 4-21b, p. 114
Fig. 4-22, p. 115
Fig. 4-23a, p. 116
Fig. 4-23b, p. 116
Fig. 4-23b, p. 116
3,940 meters; 12,000 feet
28°N 50°W4,400 meters; 14,400 feet
5,860 meters; 19,200 feet
10 miles16 kilometers
Fig. 4-24, pp. 116-117
Fig. 4-25, p. 118
Fig. 4-25, p. 118
Plate boundaryOceanic ridge
Adjacent sections here move in same direction
Sections here move in opposite directions
Adjacent sections here move in same direction
Fracture zone
(inactive)
Transform fault (active part of fracture zone)
Fracture zone
(inactive)
Lithosphere
Asthenosphere
Fig. 4-26, p. 119
Fig. 4-27, p. 119
Fig. 4-27, p. 119
Distance (km)
3 2 1 0 1 2 3
2 1Distance (mi)
1 2
Spreading axis
Hydrothermal vents and black
smokers
0 0Zone of leaching1 Ascending
superheated seawaterDep
th (
km)
1
Dep
th (
mi)
Descending seawater2
Magma chamber
0
Fig. 4-28, p. 120
Fig. 4-29a, p. 120
Fig. 4-29a, p. 120
Inactive sinking volcano being "shaved" at ocean surface
Active volcanoes
Older, extinct volcanoes
Older, extinct volcanoesSpreading
center
Sea levelG
S G GG G S G
Magma chambersLithosphere
AsthenosphereG = guyot S = seamount
50 40 30 20 10 0 10 20 30 40 50
Age of ocean floor (millions of years)
Fig. 4-29b, p. 121
Fig. 4-29b, p. 121
169°08'W
168°04'W
169°00'W14°12'S
14°16'S168°56'W
14°20'S168°52'W 14°24'S
−5,000 −4,000 −3,000 −2,000 −1,000 0 Depth (m)
−16,404 −13,123 −9,843 −6,562 −3,281 0 Depth (ft)
Fig. 4-29c, p. 121
Fig. 4-30, p. 122
Fig. 4-30, p. 122
Kuril Trench
Aleutian Trench
Philippine Trench Japan Trench
Puerto Rico TrenchMariana Trench
Middle America Trench
Kermadec–Tonga Trench
Java Trench New Hebrides
TrenchPeru–Chile
Trench
South Sandwich Trench
Challenger Deep
Fig. 4-31, p. 123
Fig. 4-31, p. 123
Guam Mariana Trench Pacific OceanD
epth
(km
)
Mount Everest (...same scale)
Dep
th (
mi)
Guam Mariana Trench
Challenger Deep
Fig. 4-32, pp. 124-125