The Coastal Zone

How do waves shape our coastline?

constructive waves destructive waves

Destructive waves formed by local storms close to the coast. strong backwash/ weak swash larger in height and closely spaced

Constructive waves formed by distant storms strong swash/ weak backwash smaller in height and well spaced apart

Mass movement

Weathering process mechanical weathering- disintegration of rocks without any chemical changes taking place. (freeze-thaw) Chemical weathering- chemical changes occur (acidic rainwater dissolve certain rocks +minerals) Biological weathering- involves the actions of flora and fauna (plant roots grow and expand in the cracks within rocks)

Coastal erosion hydraulic power- sheer power of the waves as they smash into a cliff. Air is trapped in cracks of the rocks, which causes the rock to break Corrasion- fragments of rock are picked up and hurled at the cliff by the sea. The fragments of rock scrape and gouge the cliff Abrasion- 'sandpapering' effect: pebbles grind over a rocky platform, causing it to become smooth. Solution- Vulnerable rocks are dissolved by the seawater. Attrition- rock fragments carried by the sea knock against each other, causing them to become smaller and more rounded

Coastal transportation

Suspension- lighter particles are carried within the water

Traction- large pebbles rolled along the seabed

saltation- a hopping movement of pebbles too heavy to be suspended

Solution- transporting of dissolved chemicals that are not visible

Longshore drift

Headlands and Bays

Caves, arches and stacks

Case study: Barton on Sea

Formation of a wave-cut platform Waves attack the base of a cliff using erosional processes such as hydraulic power Erosional processes create a feature called a wave-cut notch at the base of the cliff Over time, the notch becomes deeper until the overlaying cliff can no longer support its own weight, and so collapses. Through this continuous process of wave-cut notch and cliff collapse, th cliff line gradually retreats. In its place there will be a gentle sloping platform called a wave-cut platform. It is smooth due to the process of abrasion and is found at the foot of a cliff but can only be seen at low tide.

Beaches Formed from the deposition of sediment sandy beaches often found in sheltered bays wave refraction- spreads out waves and reduces their energy, causing deposition

Spits Sediment transported by longshore drift deposited where the coastline changes direction feature extends into the sea as more and more sediment is deposited. over time, the sediment will break the surface forming new land. The tip is affected by waves approaching from different directions, which can cause it to become curved.

Causes of rising sea levelsThe main cause is due to thermal expansion of sea water as it absorbs more heat from the atmosphere. This rise in heat in the atmosphere is due to global warming/ the green house gas effect.

The effects of sea-level rise in Norfolk: Settlements such as King's Lynn may be under threat as sea levels rise. Valuable agricultural land (the Fens) will be at greater risk of flooding The Norfolk Broads are a popular tourist destination bringing £5 million+ to the local area Erosion rates are likely to increase, threatening coastal settlements such as Overstand and Happisburgh. Current sea defences will need strengthening, which will be expensive. The Thames Barrier currently protects buildings worth £80 billion. It will probably need to be replaced in the next 30 to 50 years, As sea levels rise, large areas of the Lower Thames estuary will be at risk from flooding, affecting housing, industry and farmland Low-lying mudflats and marshes in Essex are particularly vulnerable to sea-level rise. Areas of salt marsh are being squeezed between sea walls and rising sea Some 22% of East Anglia's salt marshes could be lost by 2050 In some places, managed retreat (a controversial political decision) will breach sea walls to allow deliberate flooding so that salt marshes can reform

Blue = socialGreen = environmentalYellow =economicPurple =political

How waves shape our coastline

Erosional processes and transportation

Coastal landforms

Landforms from deposition

Rising sea levels