Erosion

Question 1

Hydraulic Action

Answer 1

The force of the river against the banks can cause air to be trapped in cracks and crevices. The pressure weakens the banks and gradually wears it away.

Question 2

Abrasion

Answer 2

Rocks carried along by the river wear down the river bed and banks as they crash along the banks of the river bed.

Question 3

Attrition

Answer 3

Rocks being carried by the river smash together and break into smaller, smoother and rounder particles.

Question 4

Solution

Answer 4

You cannot see this happening but soluble particles are dissolved into the river. Usually limestone or other softer dissolvable types of rock.

Question 5

what is deposition?

Answer 5

Large materials are carried along the river and become smoother and rounder until finally they become sand or silt

Reasons: obstruction, fall in volume of river or reduction of velocity

Question 6

Suspension

Answer 6

Fine, light materials carried along in the water

Question 7

Saltation

Answer 7

Small pebbles and stones are bounced along the river bed

Question 8

Traction

Answer 8

Large boulders and rocks are rolled along the river bed

Question 9

Solution

Answer 9

dissolved particles

Question 10

what does the long profile show?

Answer 10

how the river gradient changes as the river moves from its upper course, to its lower course

Question 11

what does the cross profile show?

Answer 11

how the valley shape changes as the river moves from its upper to its lower course

Question 12

why might a river deposit its load?

Answer 12

• drier weather (less water less energy)
• river slows in speed (less speed so less energy e.g. Inside bend of river)
• river floods (water onto the flood plain and deposits layers of fine silt and clay - known as alluvium- which is fertile and good for farming)