Long shore drift

• Swash: The forward movement of a wave up a beach, this pushes material up the beach at the angle of the prevailing wind, pushes material up the beach at a 45 degree angle.
• Backwash: The movement of a wave back out to see, this pulls the material straight back down the beach towards the sea, pulls it down the beach at a 90 degree angle.
• A continuation of swash and backwash moves material along a beach.
• Constructive waves: When swash is more powerful then backwash.
• Destructive waves: Where backwash is more powerful then swash - this causes beach erosion.