Rivers Flashcards
What is the river’s course split into?
Upper course
Middle course
Lower course
As the river moves from its upper course towards its lower course, what happens to the gradient?
The gradient decreases
Explain and describe the river’s upper course
In the upper course, erosion dominates over deposition.
This means that:
The valley is steep-sided and shaped like a V.
The channel that the water flows through is narrow and not very deep
Explain and describe the river’s middle course
In the middle course, neither erosion nor deposition is particularly dominant.
This means that:
The valley has a gentle slope.
The channel is wider than at the upper course. The channel is also deeper than at the upper course
Explain and describe the river’s lower course
In the lower course, deposition dominates over erosion.
This means that:
The valley is wide and flat.
The channel is wide and deep
What are the characteristics of valleys and channels in the upper courses of rivers?
Shallow channel
Narrow channel
V-shaped valley
Steep valley
Where in a river is the gradient the steepest?
Upper course
In the upper course what dominates over deposition?
Erosion
What is the upper course’s channel like?
Narrow and shallow
What is the upper course’s valley like?
Steep - sided and shaped like a V
In the middle course which process is dominant?
Neither erosion nor deposition is particularly dominant
What is the valley like in the middle course?
Has gentle slope
What is the channel like in middle course?
Channel is wider than at the upper course
Channel is also deeper than at the upper course
What process dominates the lower course?
Deposition
What is the valley like in the lower course?
Wide and flat
What is the channel like in the lower course?
Wide and deep
What are the two types of erosion that affect a river’s cross profile?
Vertical erosion and lateral erosion
What is vertical erosion?
Vertical erosion makes the river valley deeper.
Vertical erosion dominates in the upper course.
This is because high levels of turbulence make rough and angular particles drag along the river bed
Why does vertical erosion dominate the upper course?
This is because high levels of turbulence make rough and angular particles drag along the river bed
What is lateral erosion?
Lateral erosion makes the river valley wider.
Lateral erosion dominates in the lower course and middle course
What is abrasion?
where pieces of rock are picked up by the river or sea water and hit against the bed or the banks. This wears them away
What is attrition?
where pieces of bedload (material carried by a river or seawater) are hit against one another. This causes them to break apart and become smaller and more rounded
What is solution?
where soluble rocks are dissolved by the water in the river or sea (limestone and chalk in particular). They are carried along with the river or sea
What is hydraulic action?
where the force of the water hits against the river or sea bed and banks and causes the rock to break off
What are the 4 processes of transportation?
Solution
Suspension
Saltation
Traction
What is suspension?
where silt (sand, clay or other material) and sand particles are held in water (but not dissolved). The silt and sand particles are then transported along with the water
What is saltation?
where small sand and gravel particles bounce along the river bed or sea bed.
They will travel in the direction of the flow of water
What is traction?
where large rocks or large particles are dragged along the river bed or sea bed by the current
Why does deposition of sediment happen?
A river slows down
Reasons why rivers lose velocity and drop material…..?
Increased amount of sediment in the channel
Water becomes shallower
The river’s mouth is reached
Reduced volume of water in the channel
In which part of river’s does deposition not happen?
Upper course
In what part of a river world you find interlocking spurs?
Upper course
What erosional process is predominantly responsible for the formation of plunge pools?
Abrasion
Why are interlocking Spurs in the upper course?
In the upper course, rivers do not have enough energy to erode sideways (lateral erosion). Instead, they follow the winding path through the valley. These interlocking hillsides are the interlocking spurs
Hillsides on either side of a river that interlock are called…..?
Interlocking Spurs
Gorges are formed when……….retreat over time?
Waterfalls
Which processes lead to the formation of meanders?
Erosion
Deposition