River Processes Flashcards
Erosion
The wearing away of the land / break down of rock by the forces of water, wind and ice.
Hydraulic Action
The force of water and air, pushing into cracks in the river bank and bed, breaking off weaker materials.
Corrasion/Abrasion
Where particles of sand, silt and pebbles, carried in river flow, rub against the river bed and banks, wearing them away.
Attrition
Where pebbles and rocks roll along the river bed and collide or rub against each other, causing the materials to wear down or break up.
Corrosion
Where acids in the river water slowly dissolve away minerals rocks (such as calcium carbonate). This is more common with limestone and chalks.
Transportation
The movement of materials or bedload within river systems. Where materials are rolled or carried by the flow of a river.
Traction
Where larger materials, such as rocks and boulders, are rolled along the river bed.
Saltation
Where smaller pebbles are bounced along the river bed, picked up and then dropped as the flow of the river changes.
Suspension
Where finer particles of sand and silts are carried along in the river flow, giving the river a brown appearance.
Solution
Where minerals, such as limestone and chalk, are dissolved in river water and carried along in the flow. These particles are so small they can barely be seen.
Deposition
The process by which materials/bedload is dropped (dumped/deposited). This usually occurs where the flow of the river has slowed down or changed.
Vertical Erosion
This is where a river is worn away in a downwards action, making the river deeper. This usually occurs, where the gradient of slope is steep so gravity forces erosion downwards.
Lateral Erosion
This is where a river is eroded sideways, causing it to become wider. Here the slope gradient is shallower, so the river is less influenced by gravity, so it can force into the sides of the river.
Headward Erosion
This is where a river cuts forwards, making a river longer.
