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St. Michael’s RC School
The Upper Course of a River
St. Michael’s RC School
Processes of river erosion
Hydraulic action
Abrasion
Attrition
Corrosion
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Abrasion/Corrasion
This is the process by which the bed and banks are worn down by the river’s load. The river throws these particles against the bed and banks, sometimes at high velocity.
Hydraulic Action
This process involves the force of water against the bed and banks.
Corrosion
This is the chemical action of river water. The acids in the water slowly dissolve the bed and the banks.
Attrition
Material (the load) carried by the river bump into each other and so are smoothed and broken down into smaller particles.
Processes of river erosion
St. Michael’s RC School
Source of a River
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river disappears from view hidden by this spur of land
Upper Valley - River Conwy (near Mignant Moor)
Landforms in the upper course
V-shaped valleys and interlocking spurs
Rapids
Waterfalls
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V-shaped valleys on OS map
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Upper Course of River Tees
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Waterfalls!
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Waterfall formation
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The waterfall retreats back forming a gorge (steep sided valley)
Overhang becomes unsupported and falls into the plunge pool
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High Force
St. Michael’s RC School
St. Michael’s RC School
An example of a waterfall – Gulfoss, Iceland
St. Michael’s RC School
Gulfoss is located in Southwest Iceland on the Huita River.
Gulfoss has two ‘steps’ to its waterfall. These steps are made by basalt lava while the rocks between these layers are softer, sedimentary rocks.
Its gorge is 70m deep and 3 km long!
Gulfoss
