2.2 Rivers Flashcards
What are the types of erosion?
- Hydraulic action
- Attrition
- Corrosion
- Corrasion
Hydraulic action
water and air getting into cracks in a rivers banks and bed causing erosion through increased pressure
Attrition
load crashing into each other in a river
Corrasion (abrasion)
the process of a rivers’ load crashing and rubbing into a rivers’ banks and bed causing pieces to break off
Corrosion (solution)
the process of water dissolving a rivers’ load as well as its beds and banks
What are the four types of transportation?
- traction
- saltation
- suspension
- solution
Traction
the heaviest material is rolled, or dragged along the river bed
Saltation
small rocks bounce/bump along the river bed
Suspension
small particles (e.g. clay/silt) are carried by the river bed
Solution
chemical load is carried in the water flow of the river
Upper cross-section of a river
steep gradient
narrow valley
vertical erosion
Middle cross-section of a river
V-shaped
less steep
lateral and vertical erosion
Lower cross-section of a river
flatter land
very gentle
Describe the formation of waterfalls
- soft rock erodes more quickly, under-cutting the hard rock
- the hard rock is left overhanging, because it isn’t supported, it collapses
- the fallen rocks crash into the plunge pool. they swirl around, causing erosion
- process is repeated, water moves upstream
- a steep sided gorge is formed as waterfall retreats
Benefits + problems of waterfalls
benefits:
- beauty
- tourism
- jobs related to tourism
problems:
- danger from fast flowing water
- navigation
- problems of creating transport link
- overcrowding -> pollution
