1. How Waterfalls Change Over Time
Lesson 5 – page 6

2. Lesson Aims To learn that waterfalls change over time.
To learn that waterfalls retreat backwards.
To learn that when a waterfall retreats a gorge is formed.
To learn that Sipi falls brings benefits as a tourist attraction.
Key Skill = Communication

3. Lip
Hard Rock
Soft Rock
Plunge Pool

4. Processes
Hydraulic Action
Undercutting
Abrasion

6. Activity – Draw and annotate the sketches1 4 6 7 2 5 3
The hard rock forms a lip.
The waterfall retreats backwards leaving a gorge.
Hard rock overlies soft rock.
Erosion of the plunge pool causes undercutting.
The soft rock is eroded to form a deep plunge pool.
The undercut lip collapses into the plunge pool.
Soft rock beneath the hard rock is more easily eroded.

7. Case study Sipi Falls, Uganda
What benefits do Sipi Falls bring to local people?

8. Explain the employment terms:
Extension Activity
Explain the employment terms:
Formal Sector
Informal Sector.