EROSION, TRANSPORTATION AND DEPOSITION.
- Created by: chelsie webb
- Created on: 12-08-13 15:54
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- EROSION, TRANSPORTATION AND DEPOSITION.
- EROSION
- Vertical and lateral erosion change the cross profile of a river
- Can be vertical or lateral- both happen at the same time.
- One is usually dominant over the other at different parts of the river.
- VERTICAL EROSION.
- depends on the river valley and channel, making it V-shaped.
- its dominant in the upper course of the river
- LATERAL EROSION.
- widens the river valley and channel.
- dominant in the middle and lower course
- Can be vertical or lateral- both happen at the same time.
- HYDRAULIC ACTION: force of the water breaks down rock particles away from the river channel
- ABRASION
- eroded rocks picked up by the river scrape and rub against the channel, wearing it away.
- most erosion happens by abrasion
- ATTRITION
- eroded rocks picked up by the river smash into each other and break into smaller fragments
- their edges get rounded off as they rub together
- SOLUTION: river water dissolves some types of rock; e.g. chalk and limestone
- Vertical and lateral erosion change the cross profile of a river
- TRANSPORTATION
- The material a river has eroded is transported downstream
- TRACTION: large particles like boulders are pushed along the river bed by the force of the water.
- SALTATION: pebble-sized particles are bounced along the river bed by the force of water
- SUSPENSION: small particles like silt and clay are carried along by the water
- SOLUTION: soluble materials dissolve in the water and are carried along.
- DEPOSITION
- happens when a river slows down (loses velocity)
- when a river drops the eroded material its transporting
- reasons why rivers slow down and deposit material:
- volume of water in the river falls
- river reaches its mouth
- water is shallower, e.g. on the inside of a bend
- amount of eroded material in the water increases
- EROSION
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