Download Oceanography notes:

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