1. Ocean Topography

2. Mapping the Ocean Floor
Bathymetry
measurement of ocean depths
Charting topography of ocean floor
Mapping via
Sonar – sound navigation ranging
Satellites – using microwaves
Submersibles

3. Ocean Regions
Continental Margins
Ocean basin floor
Mid ocean Ridge

4. Continental Margin
Zone of transition between continent & ocean basin floor
Undisturbed sediment covers continental margin

5. Continental Margin Atlantic – Pacific
Thick layers undisturbed sediment
Little volcanic or earthquake activity
Pacific
Narrow continental margin
Volcanic & earthquake activity

6. Continental Margin Continental shelf Continental slope
Continental rise

7. Continental Shelf
Gently sloping submerged surface extending from shoreline
Associated with coastal plain
Part of continent located under water
Undersea during interglacial periods
Mineral deposits
Large reservoirs of oil & natural gas
Huge sand & gravel deposits
Can be shallow or deep

8. Continental Slope Steep gradient leading to deep-ocean floor
Seaward edge of continental shelf
Submarine canyon
Seaward extension of a valley that was cut on the continental shelf
Occurred during time sea level was lower
Canyon carved into outer continental shelf, slope, and rise
Due to turbidity currents
Turbidity currents – downslope of sediment laden water water created when sand and mud on the continental shelf and slope are dislodged and thrown into suspension

9. Continental Rise Gentle slope Generally smooth surface
Built up by shedding of sediments from the continental block
From base of continental slope to abyssal plain

10. Ocean Basin Floor Ocean basin floor Deep ocean trenches
Area of the deep-ocean; between continental margin and oceanic ridge
Deep ocean trenches
Sites of plate convergence
One moving plate descends beneath another
Plunges back into mantle
Long, narrow creases
Most at margins of Pacific
Challenger Deep- 11,022 meters deep

11. Ocean Basin Floor Abyssal plain
Deep, flat or very gently sloping areas
Between foot of continental rise & mid oceanic ridge
Thick accumulation of fine sediment
Found in all oceans
Atlantic most extensive
due to few trenches

12. Ocean Basin Floor Abyssal hills Hills along the ocean floor
100 to 2000 meters high, several km
across

13. Ocean Basin Floor Seamount Volcanic peak rises from deep-ocean floor
Up to 1000 meters above deep-ocean floor
Steeped sided, cone shaped
Found floors of all oceans, greatest number in the Pacific.
e.g. Hawaiin-Emporer
Seamont Chain; From the
Hawaiin Islands to
Aleutian trench

14. Ocean Basin Floor Guyot Table mount Flat top seamount
Formed by erosion of seamount via waves, winds, atmospheric processes

15. Mid Ocean Ridge Found near center of ocean basins
Interconnected system of underwater mountains
Developed on newly formed crust (sea floor spreading)
Winds through all major oceans
70,000 km long
1000 to 4000 km wide
Broken into segments, offset by transform faults
Oceanic spreading center

16. Mid Ocean Ridge Rift zone Found in highest part mid ocean ridge
Narrow trench (rift valley)

17. Mid Ocean Ridge Hyperthermal vents Form along mid ocean ridge
Mineral rich water heated by hot newly formed oceanic crust
Escapes through cracks in new crust to surrounding cold water