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Stages of a River Stage:Upper Course 1. Source 2. Waterfall
4 3. V-shaped valley 3 4. Steep sided valley 5. Interlocking spur
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Stages of a River Stage: Middle Course 6. Gentle Valley Sides
7. Flood-plain 8. Meander
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Stages of a River Stage: Lower Course 9. Ox-bow lake 10. Mouth
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The river flows over areas of hard rock above soft rock
How a waterfall is formed. 1. 2 3. 4. The river flows over areas of hard rock above soft rock The soft rock at the bottom of a waterfall is eroded more quickly to form a plunge pool The hard rock is undercut and becomes unsupported The hard rock above the plunge pool collapses and the waterfall moves back
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Formation of V-Shaped Valleys
erosion is mainly vertical river in its upper course has much energy so erosion takes place the steep slopes suffer from weathering erosion by the river undercuts the slope making it unstable Weathered material travels downslope to wards the river weathered material is used to erode the river channel further by abrasion
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What happens on a River Meander?
SID FOE Slower current Faster current Inside Outside (river beach) ( river cliff) Erosion of bank and bed Deposition of Sand and shingle
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In time the lake will evaporate or silt up 5.
Formation of an Ox-bow Lake The river meanders in its valley with erosion on the outside and deposition on the inside of the bend. 1. The neck of the meander becomes narrower due to erosion on the outside of the bends. 2. When the river floods it has enough energy to erode a new channel across the meander 3. The old meander is separated from the river by deposition and is left as an ox-bow lake. 4. In time the lake will evaporate or silt up 5.
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How Flood Plain and Levees are formed
Gentle valley sides Flat floodplain Coarse material Forms natural levees Layers of silt Deposited during floods
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How floodplain and levees are formed
In the lower course of a river river overflows its bank during a time of Flooding. There is a sudden loss of energy. The courser material is deposited first along the banks This forms levees. The finer material called silt is carried further by the flood water Silt is deposited over the flood plain as even more energy is lost
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River Characteristics
Upper Course Middle Course Lower Course Slope Width Depth Straightness Load amount Type of load Main work Valley width
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River Characteristics
Upper Course Middle Course Lower Course quite steep Slope usually steep gentle narrow quite wide wide Width shallow Depth quite deep deep Straightness winding meandering big meanders Load amount little some lots small+ rounded Type of load large/small angular medium/small rounded erosion transportation Transportation transportation deposition Main work Valley width narrow quite wide wide
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