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Coastal Landforms
Erosional Landforms, Depositional Landforms
Author:
Syed Ali
Edu Level: Unit1
Date: Sep 12 2025 - 4:46 PM
⏱️Read Time: 3 min
Erosional Coastal Landforms
Headlands and Bays
Headlands are resistant outcrops of hard rock that extend into the sea, while bays are indented sections between headlands.
Formation:
- Found on discordant coastlines, where bands of hard and soft rock run at right angles to the shore.
- Softer rock erodes faster, forming bays, while harder rock remains as headlands.
- Headlands face the full force of destructive waves but also shelter adjacent bays.
Examples:
- Maracas and Tyrico Bays, Trinidad.
- Swanage Bay and Headland (Old Harry Rocks), Dorset, UK.
Caves, Arches, Stacks, and Stumps
Form when headlands are attacked by waves.
Process:
- Cracks are widened into caves by hydraulic action, abrasion, and solution.
- Caves deepen; if two meet, an arch forms.
- The arch roof collapses, leaving a stack.
- The stack erodes further into a stump, visible only at low tide.
Examples:
- Hell’s Gate Arch, Antigua.
- Durdle Door Arch, Dorset, UK.
Cliffs and Wave-cut Platforms
Cliffs are steep rock faces formed where resistant rocks face strong wave attack. Undercutting creates a notch, which causes collapse. Repeated collapse leaves behind a gently sloping wave-cut platform exposed at low tide.
Examples:
- Negril Cliffs, Jamaica.
- Flamborough Head, Yorkshire, UK.
Depositional Coastal Landforms
Beaches
Beaches are accumulations of sand, pebbles, and shingle between the high and low tide marks.
- Sources: rivers, cliff erosion, longshore drift, constructive waves.
- Sandy beaches are gently sloping; shingle beaches are steeper.
- Constructive waves deposit ridges called berms.
- Material sorting: finer near the waterline, coarser near the back.
Examples:
- Maracas Beach, Trinidad.
- Brighton Beach, England.
Spits
Spits are long, narrow ridges of sand or shingle extending from the coast into the sea.
- Formed by longshore drift depositing material when the coastline changes direction or energy drops.
- Recurved ends may form due to wind or wave shifts.
- Behind spits, mudflats and salt marshes often develop.
Examples:
- Caroni Swamp, Trinidad (behind spits).
- Spurn Head, Holderness Coast, UK.
Cuspate Forelands: Triangular accumulations of sand and shingle formed by longshore drift from two directions.
Examples:
- Portland, Jamaica (Palmetto Point).
- Dungeness, Kent, UK.
Bars
A bar forms when a spit grows across a bay, connecting two headlands and trapping water to create a lagoon.
Examples:
- Mayaro Lagoon, Trinidad.
- Slapton Ley Bar, Devon, UK.
Tombolos
A tombolo is formed when a spit or sandbar connects the mainland to an offshore island.
Examples:
- Pigeon Island, St. Lucia.
- Chesil Beach linking to Portland, Dorset, UK.
Sand Dunes
Sand dunes are ridges of sand formed above the high tide mark by wind-blown sand. Vegetation such as marram grass stabilises the dunes.
Examples:
- Manzanilla Sand Dunes, Trinidad.
- Braunton Burrows, Devon, UK.
Salt Marshes
Salt marshes are wetlands formed in sheltered, low-energy areas such as behind spits. Colonised by salt-tolerant vegetation, they trap sediment and gradually build up the marsh.
Examples:
- Caroni Swamp, Trinidad.
- Thames Estuary Salt Marshes, UK.
Methods of Reducing Coastal Erosion
- Sea walls: Georgetown Seawall, Guyana; Blackpool Seawall, UK.
- Groynes: Northern Range, Trinidad; Bournemouth, UK.
- Gabions: Northern Range, Trinidad; Holderness Coast, UK.
- Beach nourishment: Maracas Bay, Trinidad; Miami Beach, USA.
- Rock armour: Maracas Bay, Trinidad; Lyme Regis, UK.
- Coastal reafforestation: Nariva Swamp, Trinidad; Mangrove restoration in Sundarbans, India-Bangladesh.
