Fluvial Landforms Geography Alevel Year12
Explain how each of the following landforms are formed including diagrams and annotated photographs. When a river runs over alternating layers of hard and soft rock, rapids and waterfalls may form
Waterfalls
A waterfall is a place where water flows over a vertical drop in the course of a stream or river. Landforms in upland regions are dominantly created by erosion processes, where land is worn away. Generally, the volume and discharge of rivers in upland regions tends to be low, and the river uses much of it's energy in overcoming friction. The erosion direction here is vertical, or straight down into the bed of the river. This has the effect of destabilising the slopes on either side of the river, creating a steep landscape They occur where a band of hard rock (e.g. granite) overlies a softer rock (e.g. sandstone). Erosion processes such as Hydraulic Action (the force of the water) and Abrasion (where the river rubs stones that are being transported against the bed of a river thereby breaking it down) dominate. The softer rock is eroded quicker than the harder rock and gradually washes away downstream. This creates a plunge pool where water is swilled around, potholing can occur here and any rocks and debris swept into the plunge pool by the river will be swirled around and rub against the bed and banks of the plunge pool (called corrasion), deepening it further. Over time, the softer rock is eroded further creating an overhang of hard rock. This overhang is unstable as it's weight is unsupported. Eventually, this hard rock collapses because it is unsupported and the waterfall moves back upstream. This creates Gorges, which are steep sided deep river valleys. This process will repeat continually, with the location of the waterfall moving back upstream
Rapids Rapids are sections of a river where the river bed has a relatively steep gradient, causing
Waterfalls
A waterfall is a place where water flows over a vertical drop in the course of a stream or river. Landforms in upland regions are dominantly created by erosion processes, where land is worn away. Generally, the volume and discharge of rivers in upland regions tends to be low, and the river uses much of it's energy in overcoming friction. The erosion direction here is vertical, or straight down into the bed of the river. This has the effect of destabilising the slopes on either side of the river, creating a steep landscape They occur where a band of hard rock (e.g. granite) overlies a softer rock (e.g. sandstone). Erosion processes such as Hydraulic Action (the force of the water) and Abrasion (where the river rubs stones that are being transported against the bed of a river thereby breaking it down) dominate. The softer rock is eroded quicker than the harder rock and gradually washes away downstream. This creates a plunge pool where water is swilled around, potholing can occur here and any rocks and debris swept into the plunge pool by the river will be swirled around and rub against the bed and banks of the plunge pool (called corrasion), deepening it further. Over time, the softer rock is eroded further creating an overhang of hard rock. This overhang is unstable as it's weight is unsupported. Eventually, this hard rock collapses because it is unsupported and the waterfall moves back upstream. This creates Gorges, which are steep sided deep river valleys. This process will repeat continually, with the location of the waterfall moving back upstream
Rapids Rapids are sections of a river where the river bed has a relatively steep gradient, causing