Coasts 3

Coasts 3

IGCSE Geography

Learning Objectives:

• Describe features such as:

  • Bars and Spits

  • Sand Dunes

  • Coral Reefs

  • Mangrove

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Deposition

Erosion

Coastal Features

Bars and Spits

These features will develop where:

• abundant material is available, particularly shingle and sand

• the coastline is irregular, for example where there is variable geology​

• where there are estuaries and major rivers​

Bars

Bars

Offshore bars are usually composed of coarse sand or shingle. As waves touch the sea bed, materials are disturbed and pushed up as offshore creating bars.

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Between the bar and the shore, lagoons (also called sounds) develop. ​

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Bars can also be driven onshore by storm winds and waves.​

If the water in the lagoon is calm and fed by rivers, marshes and mudflats can be found.

Spits

Spit

A beach of sand or shingle linked at one end to land found where wave energy is reduced (near headlands and bays, river mouths).

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The main body of the spit is curved but it has additional, smaller hooks, or recurves​.

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Spit

On the seaward side, the slope to deeper water is very steep. Within the curve of the spit, the water is shallow and a considerable area of mudflat and saltmarsh is exposed at low water.

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Saltmarshes continue to grow as mud and is trapped by the marsh vegetation.​

Sand Dunes

Coral Reefs

Sand Dunes

Dynamic environment as important changes takes place in a very short space of time.

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Extensive sandy beaches backed by sand dunes due to strong onshore winds transport the sand.

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Dunes can be blown inland and can therefore treathen coastal farmland and even villages.​

Beach conditions are very dry (water soaks into the sand) and salty.​

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Succession - the growth of new plants.

Coral Reefs

are calcium carbonate structures made up of reef-building stony corals.

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Limited to the depth that light can reach and located mostly in tropical seas, where temperatures, salinity and clear water allow them to develop.​

Fringes the coast of a landmass. They grow along shores that are protected by barrier reefs.

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Low wave energy conditions.​

Fringing reefs

Occur at a greater distance from the shore separated by a wide, deep lagoon.

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Barrier reefs are broader, older, and more continuous.​

Barrier reefs

Ring-shaped.

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Rise from the submerged volcanic foundation. Confined to the flanks of submerged oceanic islands.

Atoll reefs

Coral reefs are often described as 'rainforests of the sea' due to its rich biodiversity.

Great Barrier Reef, Australia​

Mangroves

Mangroves

Salt-tolerant forests of trees and shrubs that grow in the tidal estuaries and coastal zones of tropical areas.

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Muddy waters, rich in nutrients from decaying leaves and wood, are home to a great variety of sponges, worms, crustaceans, molluscs and algae.​

Value of Mangroves

Mangroves provide large quantities of food and fuel, building materials and medicine.

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Mangroves protect coastslines by absorbing the force of hurricanes and storms.​

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They act as natural filters, absorbing nutrients from farming and sewage disposal.​

Next Meeting: Coastal Hazards and Opportunities