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Rivers erode material from their channels, they transport material and they deposit material.
There are four main ways rivers erode, four main ways rivers transport but only one way
they deposit material -- when they don't have enough energy to transport it any more!
Erosion is the wearing away of the river bed and banks. The four main types of erosion
are hydraulic action, abrasion, attrition and solution.
Hydraulic action is where water forces air into cracks and holes in the rock and soil,
helping to break them up. Abrasion is when the rocks and stones that
are carried along by the river bash into the bed and banks, wearing them away.
Attrition is when the rocks and stones carried by the river wear each other down as they
bash into each other. Solution is when particles in the rocks and
soil of the river bed and banks get dissolved in the river water.
Transportation is when the river carries material along with it. Like erosion, this takes energy
and if the river loses energy, for example if the water flow is slowed down by an obstacle,
the river may deposit the material it was transporting.
There are four main types of transportation: traction, saltation, suspension and solution.
Traction is when large boulders are rolled along the river bed
Saltation is when small boulders and rocks are bounced along the river bed
Suspension is when lighter, smaller bits of rock and soil are carried along in the flow
of the river Solution is when material is dissolved in
the water and carried along with it.