Wide Valley

In the mature stage of a river, erosion happens laterally rather than vertically. This creates a wide river valley that is not too steep. Interlocking spurs have been removed by lateral erosion, which helps widen the valley floor. Weathering and mass movement have also contributed to making the valley less steep. 

Flood Plains

A flood plain is an area of land on either side of a river channel found in the mature and old stages of a river. Flood plains are covered in fertile soil which is called alluvium. This rich and fertile soil is full of minerals which makes it excellent for farming.