This lesson aims to teach students about different types of waves and how they impact coastlines. By the end, students should be able to name two types of waves, describe their differences, and explain how each type changes coastlines. Constructive waves are low in height and length with few occurrences per minute, depositing sediment to build wide, flat beaches. Destructive waves are high, short, and frequent, eroding steep beaches by pulling sediment offshore.

1. Lesson Objectives
This lesson is looking at the different types of wave
you can get and how they effect the coast
differently.
By the end of the lesson you should be able to:
Name the two types of wave
Describe the differences between them
Explain how they change the coastline in different
ways.

2. What is the definition of a
coastline?

3. The coast – a narrow zone where
land, sea and atmosphere meet

4. Swash and Backwash!
Swash
Backwash

5. Constructive Waves
Swash
Material deposited on beach
Backwash

6. Destructive Waves
Swash
Material eroded off beach
Backwash

7. Destructive waves mean steep, stepped beach caused by waves pulling sediment
off the beach
Constructive waves mean wide, flat and usually sandy beaches as waves deposit
sediment on the beach

8. Constructive Waves
Destructive Waves

9. Constructive and Destructive Waves
Constructive Destructive
• Height = Low (less than 1 • Height = High (more than 1
metre) metre)
• Length = Long • Length = Short
• Frequency = Fewer than 10 a • Frequency = More than 10 a
minute minute
• Energy = Low • Energy = High
• Beach gradient = flat • Beach gradient = steep
• Main process = deposition • Main process = erosion
• Stronger swash • Stronger backwash

10. Key Words
Fetch – the distance a wave has travelled
Swash – the forward movement of a wave up the beach
after the wave has broken
Backwash – water from a breaking wave which flows under
gravity down the beach
Constructive Wave – deposits sediment, building up the
beach
Destructive Wave – a wave that removes sediment from
the beach, eroding it.