Wave/ Current/ Tides – Coastal Landforms

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Other than the action of waves, the coastal landforms depend upon
  1. the configuration of land and sea floor;
  2. whether the coast is advancing (emerging) seaward or retreating (submerging) landward
Concept of evolution of coastal landforms:
  1. High, rocky coasts (submerged coasts);
  2. low, smooth, and gently sloping sedimentary coasts (emerged coasts).
High rocky coasts
  • River drowned with highly irregular coastline. hill sides drop off sharply into the water.
  • Shores do not show any depositional landforms initially. Erosion features dominate.
  • With constant pounding by waves, the cliffs recede leaving a wave-cut platform in front of the sea cliff.
  • The materials which fall off, and removed from the sea cliffs, gradually break into smaller fragments and roll to roundness, will get deposited in the offshore.
  • Deposit in the offshore, a wave-built terrace would develop in front of wave-cut terrace.
  • Bars are submerged features and Barrier bars – Bars shown up above water.Barrier bar which get keyed up to the headland of a bay is called a spit. When barrier bars and spits form at the mouth of a bay and block it, a lagoon forms.
Low sedimentary coasts
  • A long low sedimentary coasts the rivers appear to extend their length by building coastal plains and deltas. Depositional features dominate.
  • Bottom sediments get churned and move readily building bars, barrier bars, spits and lagoons.
  • The west coast - high rocky retreating coast. Erosional forms Dominate.
  • The east coast - low sedimentary coast. Depositional forms dominate.
Erosional Landforms
Cliffs, Terraces, Caves and Stacks
  • Wave-cut cliffs and terraces are two forms usually found where erosion is the dominant shore process.
  • Platforms occurring at elevations above the average height of waves is called a wave cut terrace.
  • Lashing of waves against the base of the cliff and the rock debris that gets smashed against the cliff along with lashing waves create hollows and these hollows get widened and deepened to form sea caves.
  • Resistant masses of rock, originally parts of a cliff or hill are called sea stacks.
Depositional Landforms
Beaches and Dunes
  • Characteristic of shorelines that are dominated by deposition. Occur as patches along even the rugged shores.
  • Shingle beaches contain excessively small pebbles and even cobbles.
Bars, Barriers and Spits
  • Parallel to the coast is called an off-shore bar.
  • off-shore bar which is exposed due to further addition of sand is termed a barrier bar.
  • Splits - Barrier bars get keyed up to one end of the bay.

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