Download CH 14 The Ocean Floor

CH 14.1 The Ocean Floor
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Oceanography – the study…
71 % of earth covered by oceans
Southern Hemisphere is 81 % water
Northern Hemisphere is 61 % water
4 major ocean basins
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Pacific – largest and deepest
Atlantic – narrow
Indian
Arctic
Mapping the Ocean Floor
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The topography of the ocean floor is as
diverse as that of continents
Bathymetry – measurement of ocean
depths
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HMS Challenger – 1872 - 1876
SONAR – Sound Navigation and Ranging
Satellites – Surface height from oc floor
Submersibles – manned and remote
14.2 Ocean Floor Features
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3 major regions
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1. Continental margins
2. Ocean basin floor
3. Mid-ocean ridges
1 - Continental Margins
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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)
2 - Ocean Basin Floor
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Between cont margin & mid-ocean ridge
Covers 30% of earth
Deep ocean trenches (subduction)
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Mariana Trench
Abyssal plains - Deep and flat
Seamounts - Underwater volcanoes
Guyots - Flat topped underwater
volcanoes
3 - Mid-ocean Ridges
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Underwater mountain ranges
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Long and wide
Rift zone
Transform faults
Seafloor spreading
Hydrothermal vents
14.3 Seafloor Sediments
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Can be classified according to their origin
3 categories
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Terrigenous – originates on land
Biogenous – biological in origin
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Calcareous ooze
Silicous ooze
Hydrogenous – originates from ocean water
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Manganese nodules
Seafloor Resources
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Oil and natural gas
Gas hydrates
Sand and gravel
Manganese nodules
Evaporative salts