Types Of River Systems Flashcards
What is the gradient of the upper course
Steep
What is the dominant process of the upper class , how does it occur
Erosion , occurring vertically
What are the main types of erosion
Abrasion and hydrolic action
What are 4 features of features on the upper course
Interlocking spurs
Waterfalls
Potholes
Rapids
How are potholes created in the upper class
When pebbles fall into the hollows in the rocky river bed , the water swirls the pebbles round making circular holes in the riverbed.
E.g. Bourkeskuck , potholes in mpumalanga
How does a waterfall develop
Along the river course there is a layer of restistant strata (hard rock)
Beneath this is a layer of softer rock , this softer rock is eroded away and this is called undercutting. The hard rock is left behind and a waterfall is formed . A plunge pool is formed due to the waters load
What does retreat upstream mean
Headward erosion
How do waterfalls retreat upstream
The softer rock is eroded away , there’s nothing supporting the hard rock layer. This hard rock layer eventually collapses into the river , causing the waterfall to retreat upstream.
How do waterfalls make economic importance
Hydroelectricity , tourism
What are some examples of waterfalls
Victoria falls , Zimbabwe
Howick falls
Niagra falls
What is the highest waterfall in the world
Angel falls (venesvuela )
Highest waterfall in SA
Tugela falls (KZN)
Desribe the valley of the middle class
There is more water in the river , u shaped valley . Wider with narrow floodplain.
Desribe the gradient of the middle course
Less steep (medium)
What does the middle course do , and how does it occur
Erodes and deposits. Erosion occurs vertically and laterally.
What are the main types of erosion in the middle class
Abrasion, attrition, solution
In the middle course , not much traction occurs. Why?
There are few large particles being carried by the river
What are the 2 features of the middle class
Food plains , meanders
How are food plains formed in the middle class
Formed laterally and depositing aluminum on the sides of the river, used for farming
What is alluvium in the middle class
Deposit of sedament left by flowing flood water in a river valley . Often fertile
What is the meander in the middle class
Loop like bend in a river
How is a meander formed
As the river erodes laterally over the floodplain it flows in large bends
Erosion occurs on the outside of the bend and deposition occurs on the inside of the bend , making the meander more pronounced
Describe the valley of the lower course
Wide , U shaped valley . Gradient of the river is very gentle
What is the dominant process in the lower course
Deposition