AICE Marine Science AS Chapter 2: Earth Processes Study Guide Notes

2.1 Tectonic Processes
Structure of Earth's Interior

  • Crust: Outermost layer; 5 km thick under oceans and 70 km under continents. Oceanic crust is basaltic and denser; continental crust is granite and less dense.

  • Mantle: Semi-solid rock below the crust; convection currents in the upper mantel.

  • Core: Dense center composed of iron and nickel; liquid outer core and solid inner core.

Theory of Continental Drift

  • Proposed by Alfred Wegener (1912), stating continents were connected (Pangea). Evidence includes similar fossils, geological structures, and matching shorelines.

Theory of Plate Tectonics

  • Updated continental drift theory, explaining lithosphere's tectonic plates movement. Evidence includes fossil distributions and paleomagnetic stripes.

Plate Boundaries

  • Convergent: Plates push together; subduction zones formed.

  • Divergent: Plates move apart; mid-ocean ridges create new crust.

  • Transform: Plates slide past each other; earthquakes occur due to friction.

2.2 Weathering, Erosion, and Sedimentation
Mid-Ocean Ridges and Hydrothermal Vents

  • Formed at divergent boundaries, cold water mixes with magma. Hydrothermal vents support unique ecosystems through chemosynthesis.

Weathering, Erosion, and Sedimentation

  • Weathering: Breakdown of rocks.

  • Erosion: Movement of materials.

  • Sedimentation: Accumulation of sediments in new locations.

Types of Erosion

  • Ice, Gravity, Wind, Water Erosion: Each process involves different agents of transport.

Littoral Zone Morphology

  • Rocky Shores: Durable granite; resistant to erosion.

  • Sandy Shores: Formed by wave action.

  • Muddy Shores: Calm areas with fine sediment deposition.

2.3 Tides and Ocean Currents
Estuaries and Deltas

  • Estuaries: Mixing of freshwater and saltwater creates unique ecosystems.

  • Deltas: Formed by sediment deposition at river mouths (e.g., Mississippi, Nile).

Tides

  • Caused by gravitational pull; types include semi-diurnal, diurnal, spring, and neap tides.

Factors Affecting Tidal Range

  • Coastal shape and weather; Bay of Fundy has the highest tidal range.

Ocean Currents

  • Driven by wind and density variations; includes surface and deep currents.

Global Conveyor Belt

  • Deep ocean currents circulate cold, nutrient-rich water.

Upwelling and El Niño

  • Upwelling: Nutrient-rich water rises.

  • El Niño: Warm water accumulation disrupts upwelling; impacts ecosystems.

  • La Niña: Cooling phase enhancing upwelling and productivity.