headward erosion differential erosion V-shaped valley potholes
interlocking spurs less resistant more resistant waterfall overhang gorge rapids
EXAM TIP
Students must be prepared to identify all river landforms from an OS map, a photograph or a diagram in Section 1 (short questions) OR in Part A questions (20 marks) in Section 2.
Youthful Stage – Upper Valley
Characteristics Located near the river source, the river flows through a steep-sided and narrow valley, as it: zz
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exists in an upland area with few tributaries and therefore has a small volume of water;
has a steep gradient, causing it to flow quickly and carry out vertical erosion (Fig. 8.9).
Weathered material, such as large rocks and angular stones, can be seen in the river channel. Known as the bedload, it is used as a tool of erosion (abrasion) when it is moved by traction and saltation.
Upper course (youthful stage)
Cross-section profile
V-shaped valley Gentle sloping valley Long profile
500 400 300 200 100 0
–100
Predominantly erosion
Flat and wide floodplain
Middle course (mature stage)
Lower course (old stage)
transportation and deposition
Erosion,
Predominantly deposition
Source Increasing distance downstream Fig. 8.9 Cross-section and long profile of a river valley from source to mouth.
Original source
A-Z
Vertical erosion: When the river erodes downwards into its bed. This typically occurs in the youthful stage (Fig. 8.10).
