Beach Formation and Profiles

Beaches are dynamic coastal features that change in response to wave action and sediment movement. Understanding beach formation is crucial in coastal landforms PDF studies.

Swash-Aligned Beaches

Swash-aligned beaches form when:

• Waves approach perpendicular to the shore.
• There are no prevailing winds, resulting in no longshore drift.
• The swash and backwash are aligned, limiting longshore sediment movement.
• They are common on indented coastlines where longshore sediment movement is limited.

Example: Cardigan Bay in Wales is an example of a coastline with swash-aligned beaches.

Drift-Aligned Beaches

Drift-aligned beaches are the stereotypical beach type and form when:

• Waves approach at an oblique angle to the shore.
• Sediment is moved via longshore drift.
• Waves break at different times along the beach due to imperfect refraction.
• They are associated with the formation of spits.

Vocabulary: Longshore drift - The movement of beach material along the coast by wave action.

Storm Cut and Swell Fill Beach Profiles

Beaches exhibit different profiles depending on wave conditions:

1. Storm Profile:

   • Created by steep, destructive waves.
   • Sediment is moved offshore.
   • Quick succession of waves reduces swash ability to transport sediment.
   • Results in a gentler overall gradient.

2. Swell Profile:

   • Created by constructive waves with long intervals between them.
   • Strong swash takes sediment from lower beach and deposits it higher up.
   • Creates a steeper overall gradient.

Highlight: The alternation between storm and swell profiles demonstrates the dynamic nature of beach environments.

Beach Ridge and Berm Formation

• Beach ridges form as waves are refracted on approach to the seafloor.
• Berms develop at the upper limit of wave action during normal conditions.

Definition: A berm is a nearly horizontal portion of the beach formed by the deposit of material by wave action.

Sand Dune Formation and Coastal Depositional Features

Sand dunes are important coastal landforms that develop in areas with abundant sand supply and onshore winds. Their formation is a key topic in types of coastal landforms with pictures.

Sand Dune Formation Process

1. In macrotidal areas, sand dries out during low tide.
2. Wind transports dry sand through saltation.
3. Sand accumulates around obstacles on the beach, such as vegetation or debris.
4. Embryo dunes form on the strand line, stabilized by pioneer plants like marram grass.
5. Fore dunes develop behind embryo dunes, featuring yellow dunes with more diverse vegetation.
6. Grey dunes form further inland, with a more stable environment and diverse plant communities.

Vocabulary: Saltation - The bouncing movement of sand particles caused by wind action.

Coastal Vegetation Succession

The vegetation on sand dunes changes as you move inland:

1. Blue-green algae and sea couch grass on embryo dunes.
2. Marram grass on fore dunes.
3. Sea buckthorn and other shrubs on yellow dunes.
4. Heath plants dominating grey dunes.

Highlight: The succession of plant communities on sand dunes reflects the changing environmental conditions from the beach to inland areas.

Other Coastal Depositional Features

• Spits: Form where longshore drift deposits material along a coastline, often at the mouth of estuaries.
• Salt Marshes: Develop in sheltered areas where fine sediment can accumulate and halophytic plants can grow.
• Shingle/Pebble Deposits: Form in shallow water in the lee of headlands.

Example: The formation of spits, such as Spurn Head in East Yorkshire, UK, illustrates the power of longshore drift in shaping coastal landscapes.

These coastal depositional features play crucial roles in coastal ecosystems and provide natural defenses against erosion and flooding.