3.3.1. River valley formation

What does a river's long profile show?

How its  gradient  changes

What shape does a river's long profile typically form from source to mouth?

A  concave curve 

What type of profile shows a cross-section of the river channel and valley at right angles to the flow?

Cross  profile

Which type of erosion dominates in the upper course of a river?

Vertical erosion 

What shape of valley is characteristic of the upper course of a river?

 V-shaped  valley

Which type of erosion takes over in the middle course of a river?

Lateral erosion 

What develops on the wider valley floor in the middle course of a river?

A floodplain

Which process dominates over erosion in the lower course of a river?

Deposition

What are the built-up banks found in the lower course of a river called?

Levees

Which process of erosion involves the sheer force of water trapping and compressing air in cracks?

Hydraulic action

Which process of erosion is described as rocks and sand wearing down the riverbed like sandpaper?

Abrasion

What process occurs when rocks carried by the river collide and break into smaller, smoother pieces?

Attrition

Which process of erosion involves slightly acidic river water chemically dissolving soluble rocks?

Solution

What term is used for the eroded rock material that flowing water moves downstream?

Bedload

Which method of transportation involves large stones and boulders being rolled along the river bed?

Traction

Which method of transportation involves smaller pebbles and gravel bouncing along the river bed?

Saltation

Which method of transportation involves light sediment being floated along within the water column?

Suspension

Which method of transportation involves soluble minerals being completely dissolved in the water?

Solution

What process occurs when a river loses velocity and energy, dropping its sediment?

Deposition

What causes a river to lose energy and deposit material?

• The gradient flattens

• Friction increases

• Discharge falls

• Entering standing water

What happens to water speed as the river enters gentler slopes in the middle and lower courses?

It decreases

What happens to a river's  carrying capacity  when its discharge falls during dry weather?

It reduces

Which type of material does a river drop first when it loses energy?

Largest ,  heaviest  material

What type of erosion carves a steep, narrow groove downwards into bedrock in the upper course?

Vertical erosion

Order the stages of V-shaped valley formation:

1. Vertical incision

2. Weathering and mass movement

3. Transportation

Which sub-aerial process weakens and shatters rock on steep valley sides?

Freeze-thaw  weathering

What process pulls loose material down slopes into the river channel?

Mass movement

What term describes alternating ridges of rock that jut out from both sides of a V-shaped valley?

Interlocking spurs

Why does a river wind around resistant rock in its upper course rather than cutting straight through?

It lacks the  energy