Class notes

Attrition – where material is moved along the bed of a river, collides with other material and breaks up into smaller, rounded pieces.

Corrasion – fine material rubs against the riverbank and bed. A sort of sandpapering action called abrasion wears the bank and bed away.

Corrosion – some rocks forming the banks and bed of a river are dissolved by acids in the water e.g. limestone. The rocks are then eroded.

Hydraulic action – the sheer force of turbulent water hitting the banks of the river can cause joints to be enlarged or loose fragments of rock to be swept away.

Transportation by Rivers:

• Traction – where large rocks and boulders roll or slide along the riverbed.
• Saltation – where smaller stones are bounced along the riverbed in a leap frogging motion.
• Suspension – where very small grains of sand or silt are carried along with the water.
• Solution – where some material is dissolved (like sugar in a cup of tea) and is carried downstream.