River processes
- Erosion - the wearing away of the land and the stones carried in the river.
- transportationTo move objects or people from one place to another. - the movement of rocks, sand, and silt by the river.
- depositionWhen material is deposited or left behind, eg when a river loses its energy and is unable to carry its load any further, or waves move sand onto a beach but lack the energy to carry it away. - the dumping of rocks, sand and silt wherever the river slows down.
Erosion
The main ways in which a river erodes are:
- corrasionWhen rocks carried by water wear away the landscape (also called abrasion). - wearing away of the riverbedThe land at the bottom of a river. and banks by the loadThe particles of rock carried by a river. hitting against them.
- attritionThe wearing down of the load as the rocks and pebbles hit the sea bed and each other, breaking into smaller and more rounded pieces. - wearing down of the load as the rocks and pebbles hit the river bed and each other, breaking into smaller and more rounded pieces.
- hydraulic actionErosion caused by the force of river water hitting cracks in the side of the river bank. The air in the cracks becomes compressed and then explodes outwards, breaking off bits of rock. - breaking away of the river bed and banks by the sheer force of the water getting into small cracks.
- Chemical action (corrosionWhen chemicals in the water dissolve minerals in the rocks, causing them to break up (also called solution).) - water dissolves minerals from the rocks and washes them away.
Transport
The main ways in which transport happens are:
- tractionWhen quite large stones are rolled or dragged along the river bed by the force of the water. - quite large stones can be rolled or dragged along the river bed by the force of the water.
- saltationWhen small stones which the water cannot lift bounce off each other and are carried forward by the water above the river bed for short distances. - small stones which the water cannot lift, bounce off each other and are carried forward for short distances by the water above the river bed.
- suspensionA mixture of two substances, one of which is finely divided throughout the other. - if particles are small enough the river can lift them and carry them long distances.
- solutionWhen chemicals in the water dissolve minerals in the rocks, causing them to break up (also called corrosion). - when the river dissolves minerals from the rocks they are carried in the water itself.
Deposition
The main way in which deposition happens is through loss of speed. When a river slows down on the inside of bends or when it meets deeper water - such as a lake - it loses energy and cannot carry so much. This causes it to drop some of its load.