4.3 Coastal Landscapes Flashcards
explain where in the UK has the biggest waves
Devon, Scotland, west wales, west Ireland and other places west of the UK have the biggest waves. This is because the fetch of the wave is 6000 km which gives the wave a long time to build up. Also, the strength of the wind (12 m/s) in the UK gives more energy out to the wave, making it a lot bigger. The wind duration means that the wind blows for a long time due to the westerly winds that are prevailing winds.
explain how waves break
Wind blows over water and causes friction. Water molecules in waves move in a circular orbit as energy moves through water. When a wave moves into shallow water, friction from the sea bed slows down the waves - the wave is elliptical. The wave becomes more elliptical and height increases. The water starts to rush forward - the wave is breaking. The water rushes up the beach as swash and deposits sediment on the beach. The water rushes down the beach as backwash removes sediment from the beach
Compare the characteristics of waves breaking in the summer and winter
In the summer the waves have a stronger swash than backwash, unlike in winter the waves have a stronger backwash than swash. The waves surge forward in summer whereas the waves plunge downwards in winter. In winter, the waves remove sediment from the beach through erosion, but in summer the waves adds sediment to the beach through deposition. In summer the waves have a long wave length and low wave height, but on the other hand in winter it has the opposite wave length and wave height. In summer they have a low wave frequency (6-8 waves a minute), whereas in winter the waves have a high frequency (10-14 waves a minute).
define what coastal erosion is
Erosion is the process whereby waves with high energy strike the coastline and break down and remove sediment / material
Hydraulic action
Is the power and force of air and water being forced into cracks in the rock. The pressure increases and expands. Rock chips off and the crack gets bigger.
Abrasion
When waves break, the sediment (rock) is thrown and rubbed against
the cliff.
Attrition
Waves cause rocks and pebbles to smash into each other and become
smaller and more rounded
Freeze thaw weathering
The water enters cracks in the cliff and the water freezes and expands, creating a pressure increase in the crack, the water melts, refreeezes and eventually rocks break off
Biological weathering
Plant roots go into the rock, putting pressure on it and then larger cracks are formed and after continuous cycles of this, animals burrow and break down the structure of the rock
Chemical weathering
Rainwater absorbs carbon dioxide from vegetation through transpiration, making the water mildly acidic. The carbonic acid reacts with the rocks which contain calcium carbonate and the rocks are then easily dissolved
Why do coastlines erode at different rates
Coastlines erode at different rates because some of the rock on the coast line will have headlands which are hard rock and erodes very slowly. On the other hand, the bays wiuld be soft rock and would erode quicker, forming this landscape. Also, where there is a thin layer of hard rock, once it has eroded soft rock behind it will erode faster, making another erosion happening at another different rates.
Freeze thaw weathering
The water enters cracks in the cliff and the water freezes and expands, creating a pressure increase in the crack, the water melts, refreeezes and eventually rocks break off
Biological weathering
Plant roots go into the rock, putting pressure on it and then larger cracks are formed and after continuous cycles of this, animals burrow and break down the structure of the rock
Chemical weathering
Rainwater absorbs carbon dioxide from vegetation through transpiration, making the water mildly acidic. The carbonic acid reacts with the rocks which contain calcium carbonate and the rocks are then easily dissolved
Show two examples of hard rock
Chalk and limestone
