Coasts part 1

The area where the land meets the sea

• Destructive/constructive waves
• geology 
• tides
• sea level change 
• human activity (eg. dredging)

• Wind blows across the surface of the sea which causes friction
• Friction causes the water to ripple and the surface becomes rougher and easier for the wind to grip, intensifying the size of the waves

Movement of energy through water

Highest point of wave

Lowest point of wave

Distance between 2 successive waves

Height of wave from trough to still water level

• Wind speed
• Wind strength
• Length of fetch (big fetch = big waves)

Energy = wave length x wave height²

Body of foaming water which surges up the beach

Any water returning back to the sea

Orbital flow

• Elliptical flow (rugby ball shaped) 
• As a wave approaches shallow water, friction with the sea bed increases and the base of the wave begins to slow down. This has the effect of increasing the height of the wave until it breaks onto the beach

• Low frequency, break 6-8 times a minute 
• Under 1m tall
• Widely spaced (100m apart)
• Swash stronger than backwash 
• Creates flatter beach profile

• High frequency (10-14 times a min)
• Usually over 1m tall 
• Closely spaced (20m apart)
• Backwash stronger than swash
• Creates steeper beach profile

• The coastline is irregular
• The surface of the sea is irregular 
• Waves arrive oblique (at an angle) to the coastline

• Depth of waves decreases
• Waves get higher
• Velocity decreases
• Wavelength decreases 
• Erosion to headland 
• Wave energy directed to bays 

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A section of coastline that is involved in the complete cycle of sediment transportation and deposition

The balance between the movement of smaller and larger particles into, within and out of a littoral cell

The gravitational pull of the moon

THe gap between the two high tide peaks

When the Moon and the Sun are at right angles to the Earth causing low high tides and high low tides (small tidal range) because there is less gravitational pull

When the Sun, Moon and Earth are in alignment causing high high tides and low low tides because there is a lot of gravitational pull from Moon

When meteorological conditions produce strong winds that generate waves that go over the high tide mark

• Deposited inland
• Removed by humans

Where sediment transport paths meet, sediment is deposited and builds up

Oscillations in the sea surface caused by the gravitational pull of the moon and the sun

Spring tides

• Cliff erosion
• Eroding depositional features (such as spits)

• Longshore drift
• Saltation

• Dredging
• Estuary

The breakdown of rocks in-situ on the Earth's surface

Processes operating on the land but affect the shape of the coastline, such as biological weathering

Water percolating into weaknesses in rocks and freezing. Frozen water expands by 9% causing stress on the rocks resulting in cracks.

Rocks from the cliff that have been eroded off and collected at the base of the cliff

Salt crystals left behind by evaporated salt grow over time and cause rocks to break apart

• A form of sub-aerial weathering 
• Plant roots prising apart rocks 
• Birds digging into cliffs (eg Puffins)

• Also known as wetting and drying
• The cycle of cliffs expanding when wet and contracting when dry causing clifs to crack and break up

Slow dissolving of calcium carbonate from rocks that turns into carbonic acid when it absorbs carbon dioxide in the air. Acid reacts with the rocks and dissolves them 

More effective in colder waters

Decomposition of rocks due to chemical change. For example, oxidation or carbonation

A form of weathering whereby rocks absorb water causing it to swell and become less stable