Coastal Landforms -physical Flashcards
Describe the correlation between the distance of a wave traveled and the power.
A shorter distance would mean a smaller and less powerful wave.
Constructive waves=
Low surging waves, long wave length. Strong swash, weak backwash. Beach gain. Usually associated with a gentle beach profile but overtime, it will get steeper.
Destructive waves=
Storms are usually responsible for these waves. High, plunging waves-with a short wavelength. Wave break=weak swash, strong backwash. Beach loss. Steeper beach profile although, over time, the beach will flatten.
Tidal range-
The tidal range is the vertical difference between the high tide and the succeeding low tide. Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.
Sediment cell-
A stretch of coastline, usually bordered by two headlands, where the movement of sediment tends to be contained. 11 major sediment cells have been identified in the UK.
How do tides influence the coast ? (3)
If there is a small tidal range, the power of the waves is concentrated on a relatively narrow section of a cliff. If there is a large tidal range, vast tracts of sand can become exposed at low tide. When the sand dries out, onshore winds can transport the sand to form sand dunes. Tidal currents are important in moving sediment to and from a beach.
Fetch-
The distance a wave has come before it reaches the shoreline.
Weathering at the coast=
Freeze-thaw weathering, salt weathering, biological weathering, wetting and drying, and finally, carbonation.
Freeze-thaw weathering =
Also known as ‘frost shattering’, involves water getting into cracks and pores in a cliff and then freezing to form ice. When the water freezes, it expands in volume by about 9%. This expansion exerts stress and pressure on the rock, which forces the cracks to widen. With regular freezing and thawing, some fragments of rock eventually break away to collect at the base of the cliff as ‘scree’.
Salt weathering =
Salt is already available in the tidal (or wave splash) zone. When it evaporates, it leaves salt crystals behind. These crystals can grow larger over time which then exerts stress and pressure -like ice- causing it to break apart. Salt is also able to corrode rock particularly if it contains traces of iron.
Wetting and drying weathering=
A process that is common on the shore. Clay rich rocks eg shale, expand when they get wet and contract when they dry out. This causes them to crack and therefore contribute to their breakup.
Carbonation weathering =
Involves the slow dissolving of calcium carbonate from rocks like limestone. When it absorbs carbon dioxide from the air, water forms weak carbonic acid. Then, this reacts with the calcium carbonate within certain rocks to form calcium bicarbonate. This is easily dissolved. The cooler the temperature of the water, the more carbon dioxide will be absorbed. This increases the effectiveness of carbonation.
Biological weathering=
Several types of biological weathering are: .plant roots prise apart rocks on the cliff where they grow into small cracks and then thicken and deepen with age. .water passing through decaying vegetation becomes acidic -leading to enhanced chemical weathering. .Birds, eg puffins, and animals, eg rabbits 🐰, dig burrows in cliffs. .Marine animals/organisms are also capable of burrowing into rocks, eg piddocks, or secreting acids, eg limpets.
Maldives:
A collection of coral atolls, which are badly affected by climate change.
Found in the Indian Ocean, destroying crops.
Mr Nasheed answers to ‘what do you hope to achieve?’ By replying ‘we hope not to die. I hope I can live in the Maldives and raise my grandchildren here’.
Walton on the Naze -the effectiveness to hard management :
Essex, sea wall. Groynes (wooden) Rip Rap A frame revetment, wooden but full of rocks at the end of all the groynes
