Geoscience Reference
In-Depth Information
FIG
11.
Landforms of rivers.
As the valley develops, its profile can become more complex. In some cases,
slopes appear to have retreated across a landscape some distance from the position in
which they were initially created by river down-cutting. A river with a wide valley
floor is one of the most obvious examples of this, in which movements of the channel
across the floor have caused the slopes to retreat as the valley floor has become wider.
In some cases, slopes appear to have retreated over many kilometres from the original
valley as numerous collapses of the slope took place.
Overall, therefore, the valley profile and the channel course reflect variations in
the strength of the material being eroded, and in the strength and flood pattern of the
river. Climate changes are likely to have a major effect on the strength of the river by
altering the volume of water flowing through the channels. Additionally, the lowering
or raising of the channel by Earth movement effects (see Chapter 3) can affect the evol-
ution of the landscape by river processes. For example, both climate change and the
vertical movement of the river channel can initiate the formation of river terraces. Dif-
ferent examples of all these river geometries will be discussed in greater detail in the
Area descriptions in Chapters 4-8.
