1. CH 14.1 The Ocean Floor Oceanography – the study…
71 % of earth covered by oceans
Southern Hemisphere is 81 % water
Northern Hemisphere is 61 % water
4 major ocean basins
Pacific – largest and deepest
Atlantic – narrow
Indian
Arctic

2. Mapping the Ocean Floor
The topography of the ocean floor is as diverse as that of continents
Bathymetry – measurement of ocean depths
HMS Challenger –
SONAR – Sound Navigation and Ranging
Satellites – Surface height from oc floor
Submersibles – manned and remote

3. 14.2 Ocean Floor Features 3 major regions 1. Continental margins
2. Ocean basin floor
3. Mid-ocean ridges

4. 1 - Continental Margins
Passive margins – wide shelves, no trench, sediment accumulation
Active margins – narrow shelf, trenches, volcanoes and EQs
Continental shelf – relatively flat extension of continent underwater
Continental slope – sloped surface beyond the shelf break (submarine canyons)
Continental rise – base of cont slope (turbidity currents)

5. 2 - Ocean Basin Floor Between cont margin & mid-ocean ridge
Covers 30% of earth
Deep ocean trenches (subduction)
Mariana Trench
Abyssal plains - Deep and flat
Seamounts - Underwater volcanoes
Guyots - Flat topped underwater volcanoes

6. 3 - Mid-ocean Ridges Underwater mountain ranges Long and wide
Rift zone
Transform faults
Seafloor spreading
Hydrothermal vents

7. 14.3 Seafloor Sediments Can be classified according to their origin
3 categories
Terrigenous – originates on land
Biogenous – biological in origin
Calcareous ooze
Silicous ooze
Hydrogenous – originates from ocean water
Manganese nodules

9. Seafloor Resources Oil and natural gas Gas hydrates Sand and gravel
Manganese nodules
Evaporative salts