A number of surface processes take place on rivers. These surface processes create many features along the route of the river.
• Youthful stage (Upper) Surface processes:
the ways in which weathering and erosion create different features on the Earth’s surface, and so shape the landscape.
The river course can be divided into three stages that reflect the change in gradient (slope) from the river’s source high up in the mountains to its mouth at sea level. The three stages are:
• Mature stage (Middle)
Youthful stage (Upper)
Gradient Speed Water quantity Erosion/Deposition Profile of river
Steep Fast-flowing
Low volume of water Erosion Steep, V-shaped valley Narrow, shallow channel
High level of material on river bed (larger rocks)
Landforms
V-shaped valleys Interlocking spurs Waterfalls
• Old stage (Lower)
The characteristics and landforms of each stage are set out in the table below. The landforms will be explained throughout the chapter.
Mature stage (Middle)
Gently sloping
River starts to slow down Higher volume of water Erosion and deposition
Open, gently sloping valley with flood plain Wider, deeper channel Suspended sediment
Meanders Oxbow lakes
Old stage (Lower)
Levelling off Slow-moving
Largest volume of water Deposition Flat and wide flood plain
Very wide and very deep channel
High levels of suspended sediment
Flood plains Levees
) Figure 9.2 The three stages in the course of a river
