1. Chapter 3 Marine Provinces
Essentials of Oceanography
7th Edition

2. Bathymetry
Bathymetry is the measurement of ocean depths and the charting of the shape or topography of the ocean floor
The ocean floor is a highly varied terrain that contains many interesting features
Early methods of determining ocean depths involved using a long weighted line (called a sounding line)

3. Bathymetric techniques
Echosounders send sound through water to determine water depth and sea floor features
Figure 3-1

4. Bathymetric techniques
Side-scan sonar uses a “fish” towed behind a ship to give a more detailed picture of the sea floor
Figure 3-2

5. Bathymetric techniques
Low frequency sound is used to determine structure beneath the sea floor
Figure 3-3

6. Bathymetric techniques
Satellites measure sea surface elevation, which mimics sea floor bathymetry
Figure 3D

7. The hypsographic curve
The hypsographic curve shows the relationship between the height of the land and the depth of the oceans
Figure 3-4

8. Major regions of the North Atlantic Ocean floor
Continental margin
Ocean basin floor
Mid-ocean ridge
Figure 3-5

9. Passive versus active continental margins
Passive margin
No plate boundary
Shelf
Slope
Rise
Figure 3-6

10. Passive versus active continental margins
Active margin
Plate boundary
Convergent
Shelf
Slope (steep)
Trench
Transform
Continental borderland
Figure 3-6

11. Submarine canyons and deep-sea fans
Turbidity currents carve submarine canyons into the slope and shelf
Debris from turbidity currents creates graded bedding deposits and deep-sea fans
Figure 3-8a

12. Diver in the La Jolla Submarine Canyon
Figure 3-8b

13. Abyssal plains Deep flat areas formed by suspension settling
Volcanic peaks poke through the sediment
Abyssal hills (seaknolls)
Seamounts
Tablemounts (guyots)
Figure 3-9

14. Ocean trenches Deepest parts of the ocean Formed by plate convergence
Most trenches are in the Pacific Ocean
Associated with volcanic arcs
Island arc
Continental arc
Figure 3-10

15. The mid-ocean ridge Circles the globe like the seam of a baseball
Mostly traverses the middle of ocean basins
A topographically high mountain range
Entirely volcanic in origin
Associated with plate divergence
In the Pacific Ocean, called the East Pacific Rise
In the Atlantic Ocean, called the Mid-Atlantic Ridge
Internet flybys of portions of the mid-ocean ridge

16. The Mid-Atlantic Ridge
Traverses the center of the Atlantic Ocean
Contains a central down-dropped rift valley
Comes above sea level in Iceland
Figure 3-12

17. Features of the mid-ocean ridge
Rift valleys
Form when plates split apart
Down-dropped areas associated with faults and earthquakes
Figure 3-13

18. Features of the mid-ocean ridge
Pillow lava
Forms when hot lava comes into contact with cold seawater and quickly cools
Basalt composition
Figure 3-14

19. Features of the mid-ocean ridge
Hydrothermal vents
Form when seawater is heated by magma
Black smokers emit hot water through chimneys
Associated with metal sulfide deposits and unusual lifeforms
Figure 3-15

20. Transform faults and fracture zones
Occur between segments of the mid-ocean ridge
Transform plate boundaries
Movement in opposite directions
Figure 3-16

21. Transform faults and fracture zones
Occur beyond segments of the mid-ocean ridge
Not plate boundaries
Movement in the same direction
Figure 3-16

22. Essentials of Oceanography 7th Edition
End of Chapter 3
Essentials of Oceanography
7th Edition