Lecture 3: Geology of the Ocean

• Earth's Structure: Inner core, Outer core, mantle, asthenosphere, lithosphere, crust
• Oceans formed 4.2 billion years ago
• Five major oceans: Pacific (largest), Atlantic, Indian, Arctic, Southern
• Alfred Wegener and the theory of continental drift
• Thinnest and youngest rocks are found near ridges

  Thickest and oldest rocks are found farthest away from ridges
• Divergent plate boundaries are where new lithosphere is formed
• Convergent plate boundaries is where old lithosphere is destroyed
• Faults are regions where plates move past one another
• Island arcs are formed through subduction of oceanic crust under continental crust
• Hot spots are areas of high volcanic activity, such as the island of Hawaii.
• Properties of seawater include polar bonds at 105 degrees, weak hydrogen bonds
• Hydrogen bonding and polarity influences solvent action, viscosity, thermal properties, temperature-density properties, and light
• Solvent action is how likely ionic bonds are to break
• The Principle of Constant Proportions states that the proportions of dissolved ions do not change much over the world ocean
• The major ions in seawater are: chloride, sodium, sulfate, magnesium, calcium, potassium, and bicarbonate
• Salinity can change with precipitation and evaporation (more precipitation equals lower salinity)
• The solubility of gases increase with decreased temperature and salinity
• Buffering action from bicarbonate ions, where donating H+ forms a carbonate ion and taking H+ forms carbonic acid
• Factors controlling dissolved oxygen: Biological Oxygen Demand, photosynthesis, temperature (cold water holds more oxygen), and mixing
• Oxygen in deep waters originate at the poles
• Sea surface temperatures range from -2C to 30C
• Thermocline is the zone of rapid temperature change
• Halocline is the zone of rapid salinity change
• Pycnocline is the zone of rapid density change
• Temperate seas are more productive than tropical seas due to more mixing in temperate climates
• The vertical distribution of nutrients is typically opposite that dissolved oxygen during certain times of the year in temperate waters