Geography:coastal landscapes and processes

Coastal landscapes and processes

Physical processes

Erosion is the wearing away of rocks

• Hydraulic action is the sheer power of waves smashing against the cliff and air becomes trapped causing the rock to break
• Abrasion is when rocks are thrown at the cliff
• Attrition is when rocks grind against each other becoming smoother and more rounder
• Solution is when sea water dissolves certain types of rocks

Weathering is the physical breakdown of rocks

• Mechanical weathering (freeze thaw) takes place when water collects in a rock and freezes. This causes the rock to expand and widen the crack. The water then melts and goes deeper into the crack. This process repeats until the rock is fully broken
• Chemical weathering is acid rain. Rain water is slightly acidic and it causes a weak chemical reaction to take place causing the rock to weaken and break down
• Biological weathering takes place when roots of growing plants and trees widen cracks  and burrowing animals and nesting birds can cause rocks to weaken and decay

Mass movement is a large scale downward movement of rocks and materials

• Slumping occurs after long periods of rainfall. Water seeps into the permeable rocks and where permeable rock meets impermeable rock, the saturated soil slumps along the surface
• Sliding is similar to slumping but the movement of rocks occurs along a flat surface and large amounts of soil and rock move down rapidly causing a lot of damage

Transportation is when eroded and weathered material are carried in water. These materials are deposited when the waves loses its energy

• Traction is when pebbles and larger sediments are rolled along the sea bed as they are heavy
• Saltation is when small pieces of shingle or large sand grains are bounced as they are not heavy enough to sink or light enough to float
• Suspension is when small particles are carried in the water such as silt and clay
• Solution is when minerals are dissolved in sea water and the load is not visible

Influence of geological structures

• Concordant coastlines are found when rocks run parallel to the coastline
• Discordant coastlines are found when rocks lie at right angles to the coastline forming headlands and bays

Waves are generated by wind blowing over the sea. The friction with the surface of the water causes ripples to form which grows larger into waves

• Constructive waves helps build material on the beach and has a strong swash and a weak backwash. They are formed in calm weather
• Destructive waves removes material from the coastline and has a strong backwash and a weak swash. They are formed in storm conditions

The height and energy of waves depends on:   

• Wind strength (speed): the stronger the wind the greater the friction on the sea surface, therefore the bigger the wave
• Wind duration: length of time wind blowing
• Fetch: the distance of open water which the wind has been blowing. The longer the fetch, the more powerful the wave

UK's weather and climate (to continue)

Erosional…