stones and material carried by the river hits the bed and the banks of the river, wearing them away.
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Describe the process of attrition
stones and material carried by the river collide and are broken up becoming smaller, rounder and smoother.
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Describe the erosion process of solution
slightly acidic river water dissolves chalk and limestone rocks that are made from calcium carbonate
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Describe the process of hydraulic action
the shear force of the water hitting the bed and banks, compressing air into cracks in the soil/rock forcing it to break apart.
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What are the four processes of transportation?
traction; saltation; suspension; solution
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Describe the process of traction
large rocks and boulders (bedload) are rolled or dragged along the bed of the river.
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Describe the process of saltation
small pebbles or stones are bounced along the bed of the river as the current increases/decreases in velocity.
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Describe the process of suspension
Fine light (silt) material is carried within the water body. The water looks muddy.
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Describe the transportation process of solution
the dissolved minerals carried in the river.
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When does deposition occur in a river system?
A river deposits material when the speed of flow is too slow for it to carry the load.
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Where along the river's course does deposition occur?
1) where the volume of water in a river reduces e.g. during drought; 2) on the inside of a meander 3) at the mouth of the river. Generally anywhere the energy is reduced.
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Describe a V shaped valley
A narrow valley with steep sloping sides found in a river's upper course
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Describe a waterfall
water falling from a higher level to a lower level due to a change in rock structure or a result of glacial erosion
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Describe a gorge
a steep sided narrow valley formed by a retreating waterfall
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Describe a floodplain
a flat piece of land on either side of a river forming the valley floor
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Describe a meander
a bend in the river formed by lateral (sideways) erosion
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What is vertical erosion?
erosion of the river channel which results in deepening rather than widening
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What are interlocking spurs?
Hard, resistant rocks that a river cannot easily erode and therefore the river winds around them
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What is a plunge pool?
A deepened part of the river bed at the base of a waterfall caused by the impact of the falling water
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What is differential erosion?
different rock types erode at different speeds creating landforms such as waterfalls
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What is a slip off slope (point bar)?
A Bank of gently sloping deposited material found on the inside bend of a meander
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