Chapter 8- Rivers

Question 1

What is the source?

Answer 1

Where the river begins

Question 2

What is the course?

Answer 2

The path of the river from source to mouth

Question 3

What are tributaries?

Answer 3

Small rivers that join a larger river

Question 4

What is the watershed?

Answer 4

A line dividing the waters of a river basin from the waters of another river basin

Question 5

What is a delta?

Answer 5

Land that forms at the mouth of a river due to deposition

Question 6

What is the mouth?

Answer 6

Where the river enters the sea or lake

Question 7

What is the basin?

Answer 7

The area drained by the river from source to mouth

Question 8

What is a confluence?

Answer 8

The pace where a tributary joins the main river

Question 9

What is an estuary?

Answer 9

The tidal mouth of a river

Transition between river and sea, affected by the tide

Question 10

What are distributaries?

Answer 10

Smaller rivers that break food from the main river

Question 11

What is the material transported by a river called?

Answer 11

Load

Question 12

What are the 4 methods of river erosion?

Answer 12

Hydraulic action
Abrasion
Attrition
Solution

Question 13

What is hydraulic action?

Answer 13

The force of moving water eroding the bed and the banks

Question 14

What is abrasion?

Answer 14

The load hitting of the bed and the banks wearing them away

Question 15

What is attrition?

Answer 15

The load hitting off itself, wearing itself down

Question 16

What is solution?

Answer 16

Rock minerals dissolve in a river and are carried away

Question 17

What are the four methods of river transport?

Answer 17

Solution
Suspension
Saltation
Traction

Question 18

What is suspension?

Answer 18

Light material e.g. Silt is transported in the water

Question 19

What is saltation?

Answer 19

Small stones are bounced along river bed

Question 20

What is traction?

Answer 20

Large rocks ate rolled along riverbed

Question 21

What is deposition?

Answer 21

When a river slows down, it loses energy so it deposits some of its load

Question 22

What are the 3 stages of a river?

Answer 22

Youthful
Mature
Old-age

Question 23

What are th characteristics of the youthful stage?

Answer 23

Steep slope
Fast moving
V-shaped valley: steep sides, narrow floor

Question 24

What are the characteristics of the mature stage?

Answer 24

Slower moving
Wider
Gentle slope
Mature valley: gentle sides, wide floor

Question 25

What are the characteristics of the old age stage?

Answer 25

Slow Meandering Almost flat slope Plain: little/no valley

Question 26

What stage is river erosion most active?

Answer 26

Youthful

Question 27

What is vertical erosion?

Answer 27

Wearing away of river bed

Question 28

Name 2 landforms of the youthful stage of a river

Answer 28

V-shaped valley | Waterfalls

Question 29

How are v-shaped valleys formed?

Answer 29

River wears down valley floor Weathering wears back slopes of valley Gravity causes regolith on valley sides to move downslope

Question 30

What are interlocking spurs?

Answer 30

When sides of a belly jut into each other | -created when youthful river avoids hard rocks

Question 31

When do waterfalls occur?

Answer 31

When a river falls from a height

Question 32

How are waterfalls formed?

Answer 32

A band of hard rock lies next to a band of softer rock River erodes soft rock faster, creating waterfall Plunge pool develops at base- caused by hydraulic action and abrasion River undercuts harder rock creating overhang Rock over head collapses Waterfall retreats up stream

Question 33

Name an example of a waterfall

Answer 33

Powerscourt Waterfall, Co. Wicklow

Question 34

Name 2 landforms of the mature stage

Answer 34

Floodplain | Meander

Question 35

What is a floodplain?

Answer 35

A flat area along the river corse that is flooded by the river As the river floods it lays down alluvium on the valley floor

Question 36

What is alluvium?

Answer 36

Mixture of clay, silt, sand, gravel and other material

Question 37

What are meanders?

Answer 37

Bends in the river in the mature and old age stages

Question 38

How are meanders formed?

Answer 38

*when river wears away on its outer bend and deposits on its inner bend 1. Water flows faster on outer bend- erodes bank by undercutting causing it to collapse 2. Water flows slower on inner bend- deposits load here This continues and meander becomes more prominent

Question 39

Name three landforms of the old-age stage

Answer 39

Ox-bow lakes Levees Deltas

Question 40

What is an ox-bow lake?

Answer 40

A curved shape of water formed when a meander in a river is cut off leaving the river to straighten its course

Question 41

How are ox-bow lakes formed?

Answer 41

1. River forms a meander 2. River erodes land on outer bends 3. River deposits on inner bends 4. During a flood, river breaks through to straighten course 5. Meander is cut off from river ti form ox-bow lake Eventually lake will dry out, leaving the shape in the landscape

Question 42

What is a levee?

Answer 42

A raised bank of earth running along the sides of a river