river landscapes

Question 1

what is a course?

Answer 1

the path of the river as it flows downhill

Question 2

rivers have a _____ upper course, a ______ ________ middle course and an almost ______ lower course

Answer 2

steep
gently sloping
flat

Question 3

what does the long profile of a river show you

Answer 3

how the gradient of the river changes

Question 4

what can rivers form as they flow down hill

Answer 4

channels and valleys

Question 5

what does the cross profile do?

Answer 5

shows you what a cross section of the river looks like

Question 6

what are the two types of river erosion

Answer 6

vertical or lateral

Question 7

can vertical and lateral erosion happen at the same time?

Answer 7

yes but one is usually more dominant than the other

Question 8

what does vertical erosion do?

Answer 8

• deepens the river valley and channel making it V-shaped

Question 9

where is vertical erosion dominant

Answer 9

in the upper course of the river

Question 10

what does lateral erosion do?

Answer 10

• widens the river channel and valley

Question 11

where is lateral erosion dominant

Answer 11

in the middle and lower course of the valley

Question 12

what are the four processes or erosion in rivers

Answer 12

• solution
• abrasion
• hydraulic action
• attrition

Question 13

what is hydraulic action

Answer 13

when the force of the river water colliding with the rocks breaks rock particles away from the river channel

Question 14

what is abrasion?

Answer 14

eroded rocks picked up by the river scrape against the channel causing it to wear away - most erosion happens by abrasion

Question 15

what is attrition

Answer 15

eroded rocks picked up by the river crash into each-other and break into smaller fragments and the edges get rounded off - attrition causes particle size to decrease from source to mouth

Question 16

what is solution ( erosion)

Answer 16

river water dissolves some types of rock e.g limestone and chalk

Question 17

what are the 4 different types of river transportation?

Answer 17

• solution
• saltation
• traction
• suspension

Question 18

what is traction

Answer 18

• large particles like boulders are pushed along the river bed by the force of the water

Question 19

what is saltation

Answer 19

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

Question 20

what is suspension

Answer 20

small particles like slit and slay are carried aloong by the water

Question 21

what is solution ( transportation)

Answer 21

soluble material e.g limestone dissolve in the water and are carried along.

Question 22

what is deposition

Answer 22

when a river drops the material is carrying

Question 23

when does deposition occur

Answer 23

when the river looses velocity and energy

Question 24

why does the river slow down

Answer 24

• volume of water falls
• amount of eroded material increases
• water is shallower e.g on teh inside of a bend
• the river reaches its mouth

Question 25

where are waterfalls and gorges found

Answer 25

in the upper course of a river

Question 26

where do waterfalls form

Answer 26

where a river flows over an area of hard rock followed by an area of soft rock

Question 27

how are waterfalls formeed

Answer 27

the softer rock is eroded more than the harder rock creating a ‘step in the river’
as the water flows more the step is eroded more
eventually a ‘ steep drop’ is created which is a waterfall

Question 28

what type of erosion is used to erode the soft rock in the formation of a waterfall

Answer 28

abrasion and hydraulic action

Question 29

what does fluvial mean

Answer 29

another word for river

Question 30

how is a gorge formed

Answer 30

after the formation of a water fall:

• the hard rock is undercut by erosion and becomes unsupported and eventually collapses
  the collapsed rocks swirl around the foot of the waterfall and erode the soft rock by abrasion which creates a deep ‘ plunge pool’
• over time more undercutting causes more collapse. the waterfall retreats leaving a steep sided gorge

Question 31

give an example of a waterfall

Answer 31

high force waterfall on the river tees, county durham

Question 32

why are interlocking spurs created

Answer 32

in the upper course of the river most erosion is vertical as the river lacks the power to erode laterally so the have to wind around the hillsides that stick out into their paths.

Question 33

what is the interlocking spur

Answer 33

the hillsides that interlock with each other as the river winds around them

Question 34

where do meanders and ox-bow lakes form

Answer 34

in the middle to lower course of the river where the channel as both deep and shallow sections.

Question 35

how are meanders formed

Answer 35

• the current is faster on the outside of the bend because the river channel is deeper
• the causes more erosion to happen on the outside of the bend forming river cliffs
• the current is slower on the inside because the river channel is shallower
• so eroded material is deposited on the inside of the bend creating slip-off slopes

Question 36

how are ox-bow lakes formed

Answer 36

oxbow lakes come from meanders

• erosion on the outside bends cause them to get closer
• until there only a small amount of land between the bends called the ‘neck’
• the river breaks through the neck, usually during a flood.
• and then the river flows along the shortest course
• deposition eventually cuts off the meander forming an ox-bow lake
• ox-bow lakes eventually dry up back into land

Question 37

what is a flood plain

Answer 37

a flood plain is the wide valley floor on either side of a river which occasionally floods

Question 38

what happens when a river floods

Answer 38

the water slows down, loses energy and deposits the material that its transporting which builds up the flood plain

Question 39

what are leeves

Answer 39

they are natural embankments along the edge of a river channel

Question 40

how are levees formed

Answer 40

• during a flood, eroded material is deposited onto a floodplain
• the Heaviest material is deposited closest to the channel because it gets dropped first when the river loses energy
• over time the deposited material builds up creating levees along the edge of a channel

Question 41

where are estuaries found

Answer 41

at the mouths of rivers

Question 42

how are mud flats formed

Answer 42

• at river mouths
• the water is tidal so the river level rises and falls each day
• when the river floods over the banks of the river it carries silt and and sand onto the valley floor
• as the tide reaches the highest point water moves slowly so the river has little energy and deposits sediment
• over time more sediment builds up creating large mudflats

Question 43

what are estuaries

Answer 43

estuaries are tidal areas where the river meets the sea