In the mature stage of a river, erosion occurs laterally (sideways) rather than vertically (downwards). This creates a wide river valley that is not very steep. Interlocking spurs have been removed by lateral erosion, which widens the valley floor. Weathering and mass movement have also made the valley sides less steep.
Flood Plains
Working with others:
Look at the photograph of a wide valley for a couple of minutes. Then, in pairs, discuss these questions and write down your answers.
A flood plain is an area of flat land on either side of the river channel found in the mature and old stages of a river. Flood plains are covered in fertile soil, known as alluvium. This rich and fertile soil is full of minerals and so is excellent for farming.
Flood plain
1. State two reasons why this settlement may have been built at this location?
2. Why might you not wish to build a factory too close to this river? Give two reasons for your answer.
Water at flood stage
Sand Silt and clay
Managing information and thinking:
Looking at these photographs of Bandon, Co. Cork, before and after flooding (showing the view up and down the same street), answer these questions:
1. Do you think that this area has experienced flooding in the past? Explain your answer.
2. In your opinion, will there be a large or small financial cost to the local economy? Explain your answer.
3. What measures could the local government put in place to prevent this from happening again?
