erosion, transportation, deposition and waterfalls

Question 1

name the four processes of erosion?

Answer 1

• hydraulic action
• corrasion
• attrition
• corrosion

Question 2

how does hydraulic action occur?

Answer 2

the force of the water breaks rock particles away from the river channel

Question 3

how does corrasion occur?

Answer 3

rocks that are being carried by the river rub against the channel, constantly wearing it away

Question 4

how does attrition occur?

Answer 4

eroded rocks hit against one another and break into smaller fragments

Question 5

how does corrosion occur?

Answer 5

when the river water dissolves some of the rocks, such as chalk and limestone

Question 6

name the four types of transportation?

Answer 6

• traction
• suspension
• saltation
• solution

Question 7

describe what happens in traction?

Answer 7

large particles of rock, such as boulders, are pushed along the river bed by the force of the water.

Question 8

describe what happens in suspension?

Answer 8

small particles such as slit and clay are carried along by the water

Question 9

describe what happens in saltation?

Answer 9

pebble sized particles are bounced along the river bed by the force of the water

Question 10

describe what happens in solution?

Answer 10

soluble materials are dissolved in the water and are carried along by the river

Question 11

what is deposition?

Answer 11

deposition is when a river drops the eroded material that it has been carrying

Question 12

under what condition does deposition occur?

Answer 12

when a river loses velocity (slows down)

Question 13

what causes a river to slow down?

Answer 13

• the volume of water in a river falls
• the amount of eroded material in a river increases
• the water is shallower
• the river reaches its mouth

Question 14

which course of the river are waterfalls and gorges formed in?

Answer 14

the upper course

Question 15

how are waterfalls formed

Answer 15

the river flows over an area of hard rock followed by an area of softer rock.
the softer rock is eroded faster than the harder rock which creates a step in the river, a steep drop is eventually created, which is called a waterfall

Question 16

What happens to a waterfall over time?

Answer 16

the hard rock becomes undercut, becomes unsupported and collapses, the collapsed rock erodes the bottom of the river creating a plunge pool, over time more undercutting occurs and the waterfall continues to retreat.

Question 17

when the waterfall retreats what is left behind?

Answer 17

a steep sided gorge