The sea JC Geography

Constructive waves

the swash is Greater than the backwash. Constructive waves deposit material.

Destructive Waves

coastal erosion, backwash is stronger than the swash.

Hydraulic action

The physical force of the waves breaks material off the coastline.

Abrasion

Loose material (rocks and sand) is thrown against the coastline by waves. This action breaks more material off the coastline.

Compression

When waves crash against a cliff air gets trapped in the cracks and joints on the cliff face and becomes compressed. When the waves retreat the pressure, Is suddenly released. This process of compression and released happens repeatedly until the rock eventually shatters.

Solution

Some rocks such as limestone and chalk are dissolved by water

Attrition

The stones that are carried in the water are constantly hitting against each other. Over time they become wore down smooth and rounded. This can eventually lead to the formation of sand.

What is the fetch?

The distance of open sea the wave travels over

Name a landform of coastal erosion.

Sea cliff

What is a sea cliff?

A vertical or steep slope on the coastline.

Sea cliff step 1

Waves erode a notch at a line of weakness between the high and low water mark. The notch grows bigger due to hydraulic action of waves.

Sea cliff step 2

Undercutting (cutting of waves into rock base) occurs. The rock above the notch is called the overhang, which eventually collapses

Sea cliff step 3

Processes of compression & abrasion keep on eroding the cliff so it retreats into the coastline. 

Sea cliff step 4

The rock left at the old base of the cliff is called a wave-cut platform. Material eroded from the new cliff face is deposited on the platform to form a wave-built terrace.

Sea cliff example

Cliffs of Moher, Co. Clare

Name a landform of coastal deposition.

Beach/ storm beach

Beach definition

A build-up of sand and shingle (small pebbles) deposited by constructive waves.E

Example of a beach

Bettystown Beach, Co. Meath

Example of storm beach

Port beach, Co. Louth

Beach formation step 1

When waves break they lose energy and are unable to carry their load. The swash carries material up the shore and deposits it.

Beach formation step 2

The waves are unable to carry the material because the backwash is weaker than the swash. The heaviest material is dropped first and the finer material carried closer to the shoreline.

Beach formation step 3

Over time this forms a beach. During storms waves are stronger and carry heavier material like boulders and rocks. The heavy material is deposited above the high water line, making a storm beach.

What is longshore drift?

The movement of material (sand and shingle) along the coast by waves approaching at an angle.

What drives longshore drift?

The prevailing wind, which makes waves hit the shore at an angle.

How does swash move material?

Swash moves material up the beach at the same angle as the incoming wave.

How does backwash move material?

Backwash moves material straight down the beach due to gravity.

WHAT IS RECREATION

The sea provides a lot of activities such as surfing and kayaking. this is a benefit to coastal towns. Tourism brings increased income to theses places.

Example of recreation

LAHINCH IN co. Care

Pollution problems

Marine pollution is a big problem today. Oceans are being flooded with chemicals and rubbish, things such as using farm fertilisers and littering