The sea

Notes: The Sea (3rd Year Geography)

Key Concepts:

  1. Coastal Processes

    • The sea shapes the coastline through erosion, transportation, and deposition.

  2. Waves

    • Constructive waves: Build up the coast (gentle, low energy).

    • Destructive waves: Erode the coast (high energy, strong backwash).

Erosion (Breaking Down of the Coastline)

The sea erodes the coast using H.A.S.S:

  1. Hydraulic Action

    • Waves crash into the cliffs, forcing air into cracks.

    • Pressure causes rocks to break apart.

  2. Abrasion

    • Waves pick up sand, pebbles, and stones and hurl them against the coast, wearing it down.

  3. Solution

    • Rocks like limestone dissolve in acidic seawater.

  4. Scouring

    • Waves remove loose sediment from the base of cliffs.

Erosion Landform: Sea Arch

  • Example: Durdle Door, UK

  • Formation:

    1. Waves erode a headland, creating a cave.

    2. Continued erosion deepens the cave, forming an arch.

Deposition (Building Up of the Coastline)

  • Occurs when the sea loses energy and drops its load of sand, pebbles, and silt.

Deposition Landform: Beach

  • Example: Brittas Bay, Ireland

  • Formation:

    1. Constructive waves deposit materials like sand and shingle on the shore.

    2. Longshore drift moves materials along the coast, creating a beach.

Longshore Drift (Transport of Sediments)

  1. Waves approach the shore at an angle.

  2. Swash pushes materials up the beach diagonally.

  3. Backwash pulls materials back straight down.

  4. Repeated process moves sediments along the coastline.

Tips to Remember:

  • H.A.S.S. for erosion processes.

  • Sea Arch: Cave → Arch → Collapse → Stack → Stump.

  • Deposition needs constructive waves to form beaches.