Oceanography notes (part 1):

Ocean size and names Nearly 71% of the Earth’s surface is covered by oceans. 4 major oceans ranked by size: Pacific, Atlantic, Indian, Arctic. (Southern Ocean [proposed] = considered an extension of Pacific, Atlantic, and Indian Oceans, and covers the waters that surround Antarctica)

Water distribution: 97.2% of all water on Earth is seawater.

Ocean depths: Average depth is 3688 m (12,100 ft. or ~ 2.3 mi) Deepest: Mariana Trench, 10,994 m (6.83 miles deep = 36,070 ft.). http://oceanservice.noaa.gov/facts/oceandepth.html

Currents: Currents in the ocean can be affected by differences in wind / air pressure, temperature, Coriolis effect, salinity and density.

Sea floor features:

Coastal features: Continental Margin = transition from continent to nearby ocean floor (next two combined) Continental Shelf – Part of the continent which is under water (a shallow area).  Significant due to large amounts of fish, minerals, oil/gas, sand/gravel in this area. Continental Slope – The edge of the continent; ocean drops off to deep water.

Continental slope parts: Submarine Canyons – Canyons cut into the continental slope by turbidity (sediment), currents / earthquakes (mud, sand, and water). Continental Rise – A gently sloping area at the base of the slope. Formed by turbidity flows, may be miles thick.

Ocean floor features: Abyssal Plains – The bottom, 10,000 to 20,000 feet deep. They are the flattest places on the planet as sediments have smoothed out the otherwise irregular ocean floor. Abyssal Fans – Fan shaped deposits at the end of many large rivers.

continental shelf continental shelf continental slope island guyot seamount continental slope continental rise mid-ocean ridge

Other seafloor features: Sea Mounts – Submerged volcano peaks; volcanoes that haven’t yet reached the surface to become islands. Guyots – Flat top seamounts, tops were cut off by wave action.

Ridges: Mid-Ocean Ridges – Mountain ranges which cross every ocean near the basin centers. New sea crust can form here. Hydrothermal Vents – Form along mid-ocean ridges where mineral heavy water escapes from cracks in the hot, new, oceanic crust.

Final features: Trenches – Deep troughs near continents. Where sea floor crust is pushed down into the earth and melted. Fracture Zones – Where mid-ocean ridges are broken by faults.

Oceanography notes (part 2):

Ocean study: Little was known before Sonar, invented in 1920’s. (Sonar = SOund Navigation And Ranging) The world’s largest wilderness.

Sea Water: Salinity – The dissolved solids in seawater. 3.5% of seawater is dissolved minerals / salts Measured in parts per thousand (ppt) “32 – 37 o/oo” [compare to %] Salts in seawater: Sodium Chloride (NaCl or ions) = ~ 85%

What Affects Salinity? Salinity increases with land runoff, evaporation, volcanic eruption, formation of sea ice. Salinity decreases with precipitation, melting of icebergs, sea ice.

The pycnocline: Why does the temperature spike where it does? Why does the salinity spike where it does?

Currents: Currents in the ocean can be affected by differences in wind / air pressure, temperature, Coriolis effect, salinity and density. Tsunami source??

Pacific Plate dynamics:

Pacific Plate dynamics:

OLD: Ocean depths: Average depth is 3790m (12,430 ft.) Deepest - Mariana Trench, 10,923 m (6.86 miles deep = 36,200 ft).