Starter Unscramble the key words Learning objectives To

Starter: Unscramble the key words

Learning objectives • To explain how beach material is transported along the coastline through the process of longshore drift. • To describe how deposition creates coastal landforms: beaches, spits and bars.

Coasts so far… The 2 types of wave Constructive Destructive Factors that determine the size of waves Fetch Prevailing winds

Non-sea processes that shape the coastline Mass Movement: The downhill movement of material under gravity For example: landslides (Holbeck Hall), rockfalls, mudflows and rotational slips Weathering Freeze-thaw (mechanical) and solution (chemical)

Coastal erosion processes The 4 coastal erosion processes: 1) 2) 3) 4) Coastal erosion landforms 1: Hydraulic action Abrasion Solution Attrition Coastal erosion landforms 2: Wave-cut notches and wave-cut platforms Coastal erosion landforms 3: Headlands and bays

Coastal transportation The sea uses the same 4 processes to move its load as a river does. . . Solution Suspension Traction Saltation Where waves approach the shore ‘head-on’ sediment is moved only up and down the beach, not along it. Coastal transportation is the movement of material along a coastline

Coastal transportation along the shore only occurs where the waves approach the shore at an angle Where waves approach the shore ‘at an angle’ sediment will be moved along the beach.

Longshore Drift (also known as LSD) Direction of movement Backwash is always at right angles to the beach swash Backwash The transport of sediment along a stretch of coastline caused by waves approaching the beach at an angle. Activity: Complete the worksheet

Covehithe, Suffolk LSD is in full operation on the Suffolk coast. • What problems could LSD create along the stretch of coastline pictured above? • How could these problems be solved?

A sandy beach is crucial to tourism in Southwold – the town cannot afford LSD to transport it away. Wooden groynes are used to trap the sand. Direction of Longshore drift

A B North th r o N 1. What evidence is there from the two pictures that Longshore drift is occurring at site A and B? 2. In which direction do you think LSD is operating in both pictures A and B?

Groynes Waves approach beach at an angle Sediment accumulation due to Longshore Drift

Trapping sediment in one place through the use of groynes can cause problems further along a coastline. Material is not transported and deposited, so more erosion occurs. Beaches are lost and it can accelerate cliff erosion.

How do constructive waves create beaches? Deposition! Waves run out of energy or they break in a sheltered bay. Backwash is weak and pebbles/sand is left behind. Sand dunes are formed by strong coastal winds blowing inland. The dunes are stabilised by the coarse ‘marram’ grass. Coastal deposition landform 1: beaches

By transporting material and then depositing it (when the sea loses energy) several different coastal landforms are created – called coastal depositional landforms.

Blakeney Spit, North Norfolk Direction of LSD Recurved end Spit (sand/shingle) Salt marsh

Coastal depositional landform 2: Spit Activity using page 147: Either, draw and label a diagram to show a spit is formed Or… You should include the following key words: • • Longshore drift Salt marshes Prevailing winds Estuary or river mouth Read and summarise the information and explain how a spit is formed.

Coastal depositional landform 3: Bars If a spit joins one part of the mainland to another it is called a bar. Behind the bar is trapped a freshwater lake or lagoon. Activity: Outline the main differences between a spit and a bar.

How much do you know about coasts?