Fluvial Landforms - Caused by Erosion (AQA GCSE Geography): Revision Notes
📚 Revision Notes
3.3.2 Fluvial Landforms - Caused by Erosion
Erosion Processes
- Hydraulic action
- Attrition
- Abrasion
- Solution
Waterfalls
Waterfalls
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Formation: Development:
- As water goes over the step, it erodes more of the softer rock.
- A steep drop is eventually created, called a waterfall.
- Hard rock is eventually undercut by erosion, becoming unsupported and collapsing.
- Collapsed rocks are swirled around at the foot of the waterfall, eroding the softer rock by abrasion and creating a deep plunge pool.
- Over time, more undercutting causes more collapses. The waterfall retreats, leaving behind a steep-sided gorge.
Interlocking Spurs
- Location: In the upper course of a river, most erosion is vertical, creating steep valley sides.
- Characteristics:
- Rivers aren't powerful enough to erode laterally (sideways), so they wind around high hillsides that stick out into their paths.
- The hillsides that interlock with each other like a zip as the river winds around them are called interlocking spurs.
Interlocking Spurs
Meanders
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When a river is eroding and depositing material, meanders and oxbow lakes can form.
Formation of Meanders
- Meanders: Large bends in rivers that develop in their middle and lower courses.
Current and Erosion
- Faster Current:
- Occurs on the outside of the bend.
- River channel is deeper (less friction to slow it down).
- More erosion takes place on the outside of the bend, forming river cliffs.
Formation of Meanders
- Slower Current:
- Occurs on the inside of the bend.
- River channel is shallower (more friction to slow it down).
- Eroded material is deposited on the inside of the bend, forming slip-off slopes.
- Thalweg
- The fastest flow of a river through a meander.
- The fastest flow of a river through a meander.
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Meanders get larger over time and can eventually turn into an oxbow lake.
Oxbow Lakes
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- The neck of the meander becomes progressively eroded.
Meander Process 1
- Erosion causes the river to cut through the neck during a flood.
Meander Process 2
- Deposition seals off the old meander, forming an oxbow lake.
Meander Process 3