Marine science E2

Terrigenous (Lithogenous)

• Derived from land (erosion of rocks, volcanic ash, dust).

• Transported by rivers, wind, glaciers, or turbidity currents.

Biogenous

• From the remains of living organisms (shells, skeletons of plankton).

• Made of silica (SiO₂) or calcium carbonate (CaCO₃)

Hydrogenous (Authigenic)

Precipitated directly from seawater (e.g., manganese nodules, phosphorites).

CosmogenouS

• From outer space (micrometeorites, cosmic dust, tektites).

Factors that determine sediment distribution

• Proximity to land: Terrigenous dominates near continents.

• Biological productivity: Biogenous dominates in high-productivity zones.

• Depth and dissolution: CaCO₃ dissolves below the CCD (carbonate compensation depth).

• Ocean currents: Move and sort sediments.

• Climate: Affects erosion rates and biological activity.

My favorite sediment & why

Biogenous ooze — because it’s made of microscopic shells that blanket much of the seafloor, preserving Earth’s biological history and giving clues about past climate and ocean conditions.

How and why atmospheric convection cells form

Uneven solar heating: Equator gets more direct sunlight → warm air rises → moves poleward → cools and sinks.

Hadley Cell (0–30°):

Rising warm air near equator → rain (tropics); sinking dry air at 30° → deserts.

Ferrel Cell (30–60°):

Mid-latitude mixing zone; westerly winds dominate.

Polar Cell (60–90°):

Cold air sinks at poles and flows equatorward.

Wet regions:

• Equator (ITCZ), 60° latitudes.

Dry regions:

30° (deserts), poles.

Coriolis Effect

• Apparent deflection of moving objects (air or water) due to Earth’s rotation.

• Deflection direction:

  • Right in Northern Hemisphere

  • Left in Southern Hemisphere

• Effect: Causes curved wind patterns—trade winds, westerlies, and polar easterlies.

Model (description for drawing)

• Label equator, 30°, 60°, 90° in each hemisphere.

• Show three cells (Hadley, Ferrel, Polar).

• Add prevailing winds:

  • Trade Winds: East → West (deflected right/left).

  • Westerlies: West → East.

  • Polar Easterlies: East → West.

Ekman Spiral

• Wind → surface water → moves at 45° to wind direction (due to Coriolis).

• Each deeper layer moves slower and more rotated → forms a spiral pattern.

• Net transport (Ekman transport): 90° to the right (NH) or left (SH) of the wind.

Geostrophic Flow

• Forms when pressure gradient force (from water piled up in gyre centers) is balanced by the Coriolis force.

• Keeps gyres circulating even when winds weaken.

Western Intensification

Due to Earth’s rotation and Coriolis effect, the western boundary currents (like the Gulf Stream, Kuroshio) are narrow, deep, and fast, while eastern boundary currents (like California Current) are broad, shallow, and slow.

Upwelling

Surface water moves away → deep, nutrient-rich water rises → increases primary productivity.

Downwelling

Surface water piles up and sinks → transports oxygen to deep ocean.

Major upwelling regions

• Equatorial Pacific

• Coasts of Peru, California, Canary Islands, and Benguela (South Africa)

Crest

Highest point of a wave

Trough

Lowest point of a wave

Wavelength

Distance between crests

Wave height

Vertical distance crest–trough

Wave period

Time for one wavelength to pass a point

Capillary waves, Wind (gravity) waves, Tsunamis, Tides

Ocean swell vs sea

• Sea: Choppy waves in the area where wind is blowing.

• Swell: Long, uniform waves that have traveled out of their generating area.

Constructive

Crests align → bigger waves.

Destructive

Crest meets trough → smaller wave or cancellation.

Mixed

Combination, leading to irregular wave heights.

Wave interference

Constructive, destructive, mixed

Why waves break near shore

As waves approach shallow water, bottom friction slows the wave base → wavelength shortens, height increases → wave becomes unstable and breaks.

How Earth, Moon, and Sun create tides

Tides are caused by the gravitational pull of the Moon and Sun on Earth’s oceans.

Two bulges:

1. Facing the Moon (gravitational pull).

2. Opposite side (inertia from Earth–Moon system rotation).

Spring tides:

• Sun, Moon, and Earth aligned (new & full moon)

• Highest highs and lowest lows (greatest tidal range).

Neap tides:

• Sun and Moon at 90° (first & third quarter).

• Lowest tidal range.