Upper-course river features include steep-sided V-shaped valleys, interlocking spurs, rapids, waterfalls and gorges.
Middle-course-river features include wider, shallower valleys, meanders, and oxbow lakes.
Lower-course river features include wide flat-bottomed valleys, floodplains and deltas.
As the river moves through the upper course it cuts downwards. The gradient here is steep and the river channel is narrow. Vertical erosion in this highland part of the river helps to create steep sided V-shaped valleys, interlocking spurs, rapids, waterfalls and gorges:
As the river erodes the landscape in the upper course, it winds and bends to avoid areas of hard rock. This createsinterlocking spurs, which look a bit like the interlocking parts of a zip.
When a river runs over alternating layers of hard and soft rock, rapids and waterfalls may form.
Middle course features
In the middle course the river has more energy and a high volume of water. The gradient here is gentle and lateral (sideways) erosion has widened the river channel. The river channel has also deepened. A larger river channel means there is less friction, so the water flows faster: