Sea And River Formations

Question 1

How is a spit formed?

Answer 1

1. Sediment is carried by longshore drift.
2. When there is a change in the shape of the coastline, deposition occurs. A long thin ridge of material is deposited. This is the spit.
3. A hooked end can form if there is a change in prevailing wind direction
4. Waves cannot get past a spit, therefore the water behind a spit is very sheltered. Silts are deposited here to form salt marshes or mud flats.

Question 2

How is a beach formed?

Answer 2

Beaches are made up from eroded material that has been transported from elsewhere and then deposited by the sea. For this to occur, waves must have limited energy, so beaches often form in sheltered areas like bays. Constructive waves build up beaches as they have a strong swash and a weak backwash.

Question 3

How is a bar formed?

Answer 3

Longshore drift occurs pushing sediment past a headland and as the spit gets closer and close to another headland which is across a bay. Once it connects to the other headland. A lagoon forms of salty water behind the newly formed bar. Lagoons don’t last forever and the sediment gathers.

Question 4

Coastal landforms from erosion: cliff retreat.

Answer 4

Hydraulic action and abrasion occur at the bottom of the cliff and a wave cut notch forms in the side of the cliff which allows more erosion to occur. The rock at the top of the cliff becomes unstable and once the notch gets too deep the rock collapses. This fallen rock forms a wave cut platform. The cliff moves back as this process repeats over time.

Question 5

What factors increase the rate of retreat of a cliff?

Answer 5

Geology, the type of wave (destructive waves erode faster), bad weather weakens the top of the cliff which falls faster e.g storms, human defences slow the process.

Question 6

Coastal formation from erosion: formation of stumps

Answer 6

Abrasion and hydraulic action form a crack in the cliff. This occurs until the crack turns into a cave. This again occurs until the cave turns into an arch arch erodes and falls forming a stack. This is eroded on the bottom and it falls leaving only a stump behind.

Question 7

How is material transported along the coast: longshore drift

Answer 7

Swash hits the beach at an angle of the prevailing wind and the backwash pulls back at 90 degrees. This process occurs along the shoreline

Question 8

What affects the amount of material which is deposited?

Answer 8

If erosion on the nearby coast is high, then lots of rock and sand will fall into the ocean. This will increase deposition on nearby beaches. The more sediment in the ocean, the more deposition there will be.