rivers

Question 1

what is the upper course gradient , valley and channel shape ?

Answer 1

steep gradient , v shaped valley , steep sides narrow shallow channel

Question 2

what is the middle course gradient , valley and channel shape ?

Answer 2

medium gradient , gentle slopping valley sides , wider deep channel

Question 3

what is lower course gradient , valley and channel shape ?

Answer 3

gentle gradient , very wide almost flat valley , very wide and deep channel

Question 4

what is vertical erosion ?

Answer 4

• this deepens the river valley and channel , making it v shaped ,
• dominant in the upper course of river

Question 5

what is lateral erosion ?

Answer 5

• this widens the river valley and channel
• dominant in the middle and lower courses

Question 6

what is long profile ?

Answer 6

long profile of river shows you how the gradient ( steepness ) changes over time

Question 7

what is cross profile ?

Answer 7

shows you the cross section of a river

Question 8

what are the 4 processes of Erosion ?

Answer 8

hydraulic action
solution
abrasion
attrition

Question 9

what is hydraulic action ?

Answer 9

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

Question 10

what is abrasion ?

Answer 10

when pebbles grind along a rock platform, much like sandpaper. Over time the rock becomes smooth

Question 11

what is attrition ?

Answer 11

this is when rocks that the sea is carrying knock against each other. They break apart to become smaller and more rounded.

Question 12

what is solution ( corrosion )

Answer 12

river water dissolves certain types of rock
ex. limestone

Question 13

what is transpiration ?

Answer 13

movement of eroded material

Question 14

what are 4 types of transportation ?

Answer 14

• traction
• suspension
• saltation
• solution

Question 15

what is traction ?

Answer 15

• large particle likes boulders are pushed along the river bed by force of the water.

Question 16

what is suspension ?

Answer 16

• small particle like silt and clay are carried along by the water .

Question 17

what is saltation ?

Answer 17

pebble sized particles bounce along the river bed by the force of water.

Question 18

what is solution

Answer 18

soluble materials dissolves in the water and are carried along .

Question 19

what is deposition ?

Answer 19

when river drops eroded material .

Question 20

when does deposition occur ?

Answer 20

happens when river slows down , ( loses velocity )

Question 21

why does the river slow down and deposit material , basically why does deposition occur ?

Answer 21

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

Question 22

how do oxbow lakes form ?

Answer 22

1 - erosion causes the outside bends to get closer
2 - until theres a little bit of land left between the bends
3 - river breaks through the little bit of land left usually during a flood
4 - rivers then starts to flow along the shortest course
5 - deposition eventually cuts of the meander
6 - forming an oxbow lake

Question 23

how do rivers meander ?

Answer 23

1 - current is faster on the outside of the bend because theres a deeper river channel which makes it deeper . (less friction to slow water down )

2 - so more erosion takes place on the outside of the bend forming river cliffs

3 - current is slower on the inside of the bend because river channel is shallower ( theres more friction to slow it down ).

4- so eroded material is deposited inside of the bend forming slip off slopes