Waterfall Formation

Waterfalls form where the river bed has a layer of harder rock overlying the softer rocks.

1. As water falls the softer rock is eroded much more quickly than the harder rock; therefore undercutting the harder rock.
2. The hard, overrhanging rock eventurally collapses.
3. The collapsed rocks fall into the plunge pool causing more erosion of the soft rocks and a deeper plunge pool.
4. This goes on continuously causing the waterfall to retreat upstream.
5. The waterfall leaves a steap sided gorge as it reatrets.

Waterfalls may also be caused as a result of:

• Glacial Erosion
• A Fall in Sea Level
• Earth Movement