River Processes

Question 1

Hydraulic action

Answer 1

Force of water breaks rock particles away from river channel

Question 2

Abrasion

Answer 2

Eroded rock picked up by scrape and rub against the channel. Most erosion happens by abrasion .

Question 3

Attrition

Answer 3

Eroded rock picks up the river and smashed into each other making them smaller .

Question 4

Solution

Answer 4

River water dissolves some type of rock , e.g. chalk,limestone

Question 5

Freeze thaw weathering

Answer 5

1-Its where the temperature alternates above and below 0 degrees ( freezing point of water )

2-Water gets into cracks and then when it freezes it expands which put pressure on rocks and then cracks and makes gaps in the rock.

3-Repeated freezing and crack widens causes rock to break up.

Question 6

Traction

Answer 6

Large particles pushed along the river bed by the force of water

Question 7

Suspension

Answer 7

Small particles like silt and clay are carried along by the water

Question 8

Saltation

Answer 8

Pebble sized particles bounce along the river bed by force of water

Question 9

Solution

Answer 9

They are materials that dissolve in the water and are carried along.

Question 10

Deposition

Answer 10

When the river drops the eroded material when its transporting.

Question 11

Why river slow down?

Answer 11

• the volume of water in river falls
• the amount of eroded material in the water increases
• the water is shallow , inside of bend
• river reaches the mouth

Question 12

Ox-bow lakes are formed by …?

Answer 12

Meanders

Question 13

How are oxbow lakes formed?(6 steps)

Answer 13

1. Erosion causes the bends to get closer
2. Until theres only a small bit of land left between bends (neck)
3. The river breaks through this land , usually during a flood
4. The river flows along the shortest course
5. Deposition eventually cuts off the meander
6. Forms an oxbow lake