SPECIFICATION TARGET: to be able to explain the impact of weathering, erosion and mass movement on river landscapes.

Key Point Rivers are channels of water which drain the land’s surface. They erode, transport and deposit materials, creating steep valleys and wide floodplains. As river’s cut into the landscape they expose bedrock, leading to further change through weathering and mass movement.

Processes of river erosion Hydraulic action Attrition Corrosion Abrasion

Definitions Hydraulic Action This process involves the force of water against the bed and banks. 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. Attrition Material (the load) carried by the river bump into each other and so are smoothed and broken down into smaller particles. Corrosion This is the chemical action of river water. The acids in the water slowly dissolve the bed and the banks.

Do you know your processes of erosion?

Freeze thaw Biological Chemical Weathering

Soil creep Individual particles of soil move slowly down a slope under gravity and then collect at the bottom. The river may then erode this material.

slumping When the bottom of the valley side is eroded by the river. This makes the slope steeper and the valley side material can slide downwards in a rotational manner, often triggered by rain which lubricates the rock and makes it much heavier.