River Processes Flashcards
What is a process?
A set of activities that interact to achieve a result
What are the three main river processes?
Erosion, transportation and deposition
What is erosion?
The process that wears away the river bed and banks
What is transportation?
The act of rivers transporting materials
What is deposition?
When rivers drop the material they’ve been carrying
What are the four subsections in erosion?
Hydraulic action, abrasion, attrition and solution
What is hydraulic action?
Where fast flowing water is forced into cracks and breaks up the bank over time
What is abrasion?
Where sand or pebbles get dragged along the river bed or knock into it by saltation wearing away the bank
What is attrition?
When rocks knock together and wear each other away
What is solution?
When alkaline rocks get dissolved by acidic rain water
What are the four subsections of transportation?
Traction, saltation, suspension and solution
What is traction?
When large stones get dragged along the river bed
What is saltation?
When smaller stones are picked up then dropped giving them a bouncing motion
What is suspension?
When tiny particles are carried in the river’s current
What is solution in transportation?
When dissolved chemicals, invisible to the naked eye are carried along the river
When does erosion happen?
If a river has a lot of energy left after overcoming friction ( a fast flowing, efficient channel)
When does deposition happen?
If a river does not have enough energy to carry load
What are the three types of weathering that happen in a river valley?
Physical, chemical and biological
What is physical weathering and give an example?
When physical force breaks rocks into pieces e.g. freeze thaw.
What is chemical weathering and give an example?
Any chemical change/ decay of a solid rock e.g acid rain on limestone
What is biological weathering?
Where small cracks allow plant roots to penetrate forcing the cracks apart as the plant grows
What are the two types of mass movement and state if they are rapid or slow?
Soil creep (slow) and slumping (rapid)
What is soil creep?
When rain dislodges tiny soil particles at a rate of around 2m per year
What is slumping?
Where a large segment of the cliff moves down-slope
