river processes

Question 1

what is erosion

Answer 1

Erosion is the process that wears away the river bed and banks. Erosion also breaks up the rocks that are carried by the river.

Question 2

what are the four types of erosion

Answer 2

abrasion, hydraulic action, attrition, corrosion/solution

Question 3

how does abrasion work

Answer 3

rocks rub across the landscape in a sandpaper like effect eroding the landscape

Question 4

how does hydraulic action work

Answer 4

the force of waves crashing into the landscape breaking and eroding it

Question 5

how does attrition work

Answer 5

two rocks smash into eachother in the water eventually making eachother smoother and smaller

Question 6

how does corrosion/solution work

Answer 6

This is the chemical action of river water. The acids in the water slowly dissolve the bed and the banks.

Question 7

what is vertical erosion

Answer 7

Vertical erosion is downwards and creates v-shaped valleys and waterfalls

Question 8

what is lateral erosion

Answer 8

Lateral erosion is side to side and creates meanders

Question 9

what is physical weathering

Answer 9

breaking rocks into smaller and smaller pieces and can be done by changes in temperature and by rain expanding after freezing in a gap

Question 10

what is chemical weathering

Answer 10

causes rocks to decay and slightly disintegrate and is usually caused through acid rain

Question 11

what is biological weathering

Answer 11

the roots of plants, especially trees growing into cracks in rocks and eventually separating the rocks

Question 12

what is mass movement

Answer 12

Once rocks are broken down the weathered material starts to move down the slope under the influence of gravity

Question 13

what is slumping

Answer 13

The bottom of a valley side slope is cut away by the river flowing at it’s base. It makes the slope unstable and weathered material slumps down towards the river.

Question 14

what is soil creep

Answer 14

Weathered material moves slowly down slope under the influence of gravity. It collects at the bottom of the valley side and is eroded by the river.

Question 15

what is a rivers load

Answer 15

the material transported down it

Question 16

what is traction

Answer 16

large, heavy pebbles are rolled along the river bed. This is most common near the source of a river, as here the load is larger.

Question 17

what is saltation

Answer 17

pebbles are bounced along the river bed, most commonly near the source.

Question 18

what is suspension

Answer 18

lighter sediment is suspended (carried) within the water, most commonly near the mouth of the river.

Question 19

what is solution

Answer 19

the transport of dissolved chemicals. This varies along the river depending on the presence of soluble rocks.

Question 20

what is the long profile of a river

Answer 20

The long profile shows the gradient of a river as it journeys from source to mouth. It spans the source of a river (where it starts) and the mouth (where it reaches the sea).

Question 21

what is the point of the long profile of a river

Answer 21

The long profile of a river is a way of displaying the channel slope (gradient) of a river along its entire length. Therefore, it shows how a river loses height with increasing distance towards the sea.

Question 22

what is the cross profile of a river

Answer 22

A cross profile is a section taken sideways across a river and/or valley. It is an imaginary ‘slice’ across a river channel and its valley.