OCEANS, COASTAL PROCESSES & LANDFORMS
70.78% of the Earth is covered by water. Of this 96.53% is in the oceans & ~3.47% is
freshwater, in the ppm are organisms & dust.
Ocean Factoids
Area = 361 x 106 km2 (139 x 106 mi2)
Volume = 1.37 x 109 km3 (329 x 106 mi3); 0.13% of Earth’s volume
Mass = 141 x 1018 mt, 0.02% of Earth’s mass
Average Depth = ~3796 m (12,451 ft)
Deepest part = 11,022 m (36,163 ft), the Challenger Deep in the Mariana Trench
Average Salinity = 34.7 g/kg (‰); 3.47%
Amount of Salt = 4.6 x 1012 mt
Average Temperature = 3.9°C (39°F)
Average pH = ~8 (slightly alkaline)
Age = ~ 4 x 109 yrs
Northern Hemisphere is 60.7% sea & 39.3% land
Southern Hemisphere is 80.9% sea & 19.1% land
Salinity - measure of the quantity of total dissolved solids (TDS) in ocean water,
measured in g/kg, ppt, ‰
These TDS come from the erosion of crustal rock & excess volatiles from deep crustal &
upper mantle sources through volcanism
Salinity Components - only 6 elements make up >99% of the TDS;
the water is 85.8% O & 10.7% H
chlorine, Cl
55.04%
sodium, Na+
30.61
2sulfur (as sulfate), SO4
7.68
magnesium, Mg2+
3.69
2+
calcium, Ca
1.16
potassium, K+
1.10
99.28
Physical Structure of the Ocean - exhibits density stratification
1) surface zone - upper layer of the ocean (~2% of the ocean’s volume) where
temperature & salinity are relatively constant; varies in depth from 0 to 150 m
2) thermocline (therm: heat & clinare: slope) - middle layer where temperature changes
rapidly with depth; primarily in the mid & low latitudes
3) deep zone - very cold layer, ranging in temperature from -1° to 3°C (~80% of the
ocean’s volume)