Fetch is the distance over which wave-forming winds blow before reaching the land.
2. Explain how Britain is affected by winds with a variety of different fetches. (3)
As Britain is an island off the coast of Europe it is affected by winds with short fetches such as easterly winds across the English Channel from northern France or westerly winds across the Irish Sea. North-easterly winds blowing from Scandinavia across the North Sea have a longer fetch. Meanwhile, south-westerly winds blowing onto the south and west coasts of the UK may have a fetch a several thousand kilometres.
3. With the aid of a diagram, describe the formation of a wave-cut platform. (4)
Wave-cut platforms form from the progressive erosion – by abrasion and wave pounding - and the collapse of coastal cliffs results in the formation of a gently shelving expanse of rock at the base of the cliffs. This is usually exposed at low tide.
4. Describe and explain the formation of two or more erosional features of a rocky headland. (6)
As waves approach a rocky headland, refraction acts to concentrate the wave energy on both sides of the headland. Weaknesses in the rock such as cracks or joints are opened up by the hydraulic action of the waves crashing against them. Over time the crack expands to form sea caves. These can be deepened by abrasion from the broken rock being rolled up and down the cave by the waves. In time two caves may erode back to back and join together to form a sea arch.
Further weathering by sub-aerial processes of the arch roof can lead to its collapse. As a result column of rock, called a sea stack, may be left behind rising on its own from the wave cut platform. Eventually, this will collapse to leave behind the rains of its base as a stump.
5. Explain what is meant by a sub-aerial process. (2)
Sub-aerial processes are land processes such as chemical and freeze-thaw weathering and mass movement which are active on and help shape a coastline.
6. Describe the relationship between wind and waves at sea (3)
Wave are formed from the friction of wind blowing over the sea. This friction transfers wind energy into the wave. While the water molecules in a wave travel in circles the energy is transferred in the direction of the wind. Strong winds blowing over a large distance, called the fetch, can result in waves with a long length and relatively low height. Winds blowing over a short fetch can produce more choppy seas with waves with a shortwave and a relatively greater height.
7. Contrast the swash and backwash of a wave. (3)
The swash is the movement of water up a beach after a wave breaks upon it whereas the backwash is the movement of water down the beach as the wave retreats. The direction of swash is determined by the angle of wave approach whereas the backwash retreats under gravity at right angles to the slope of the beach.
5. Explain what is meant by a sub-aerial process. (2)
Sub-aerial processes are land processes such as chemical and freeze-thaw weathering and mass movement which are active on and help shape a coastline.
6. Describe the relationship between wind and waves at sea (3)
Wave are formed from the friction of wind blowing over the sea. This friction transfers wind energy into the wave. While the water molecules in a wave travel in circles the energy is transferred in the direction of the wind. Strong winds blowing over a large distance, called the fetch, can result in waves with a long length and relatively low height. Winds blowing over a short fetch can produce more choppy seas with waves with a shortwave and a relatively greater height.
7. Contrast the swash and backwash of a wave. (3)
The swash is the movement of water up a beach after a wave breaks upon it whereas the backwash is the movement of water down the beach as the wave retreats. The direction of swash is determined by the angle of wave approach whereas the backwash retreats under gravity at right angles to the slope of the beach.
