River landforms
Erosional landforms include V-shaped valleys, interlocking spurs, waterfalls and gorges. Meanders and oxbow lakes use erosional and depositional processes in their creation.
Erosional landforms
The process of erosion can create different landforms. The erosional features are often found in the upper course of the river.
Waterfalls and gorges
A waterfall is a sudden drop along the river course. It forms when there are horizontal bands of resistant rock (hard rock) positioned over exposed, less resistant rock (soft rock).
- The soft rock is eroded quicker than the hard rock and this creates a step.
- As erosion continues, the hard rock is undercut forming an overhang.
- Abrasion and hydraulic action erode to create a plunge pool.
- Over time this gets bigger, increasing the size of the overhang until the hard rock is no longer supported and it collapses.
- This process continues and the waterfall retreats upstream.
- A steep-sided valley is left where the waterfall once was. This is called a gorge.
V-shaped valleys and interlocking spurs
In the upper course there is more vertical erosion. The river cuts down into the valley to form a narrow, steep-sided V-shaped valley. If there are areas of hard rock which are harder to erode, the river will bend around it. This creates interlocking spurs of land which link together like the teeth of a zip.
