IGCSE Marine Science: The Earth and Its Oceans

Overview

• Understanding the relation between the Earth, Moon, and Sun.
• Exploring the internal structure of the Earth and its effects on oceans.
• Identifying the five oceans and the flow of water.
• Examining tides, tsunamis, and rip currents.

Motion of the Earth, Moon, and Sun

• Natural Satellite: The Moon is a natural satellite of the Earth.
• Gravitational Forces:
  • Gravity keeps the Earth in orbit around the Sun.
  • Gravity also maintains the Moon's orbit around the Earth.

Internal Structure of the Earth

• Layers of the Earth:
  • Crust: Thin, solid outer layer.
  • Mantle: Semi-molten layer beneath the crust.
  • Core: Mostly iron, generating the Earth's magnetic field.
• Tectonic Plates:
  • The Earth's crust is broken into large tectonic plates.
  • Movement caused by convection currents in the mantle.

Plate Boundaries

• Types of movements:
  • Convergent Boundaries: Plates move toward each other.
  • Divergent Boundaries: Plates move apart.
  • Transform Boundaries: Plates slide past each other.
• Consequences:
  • Movement can cause earthquakes.
  • Formation of geological features like volcanoes, mid-ocean ridges, and ocean trenches.

Oceans and Water Flow

Distinct Oceans

• The Earth has five main oceans:
  • Pacific Ocean
  • Atlantic Ocean
  • Indian Ocean
  • Southern Ocean
  • Arctic Ocean
• Oceans are interconnected, forming a world ocean covering more than two-thirds of the planet.

Ocean Currents

• Oceanic Currents: Continuous flow of seawater in a specific direction, influenced by:
  • Prevailing winds
  • Earth's rotation (Coriolis effect)
  • Changes in seawater density
• Gyres: Large circular systems of ocean currents, five main gyres in major oceans.

Tides

• Causes of Tides:
  • Result from the gravitational pull of the Moon and Sun on ocean water.
• Tidal Changes:
  • Spring Tides: Higher tidal amplitude when the Moon is full or new.
  • Neap Tides: Lower tidal amplitude when the Moon is in the first or last quarter.

Tsunamis and Rip Currents

Tsunamis

• Formation: Caused by sudden displacement of large volumes of seawater.
• Effects: Can devastate marine life and coastal communities.

Rip Currents

• Description: Strong, narrow channels of water flowing away from the shore.
• Danger: Can pose significant risk to swimmers along beaches and coastlines.