this slide helps IGCSE to be able to revise and grasp the main topic of rivers

1. River features?
Are facial
features the
same thing for
rivers?
1

2. River Features
Rivers are eroding, transporting and depositing
constantly.
The river can be divided into 3 sections –
Upper Course at the Source, Middle Course
and Lower Course at the Mouth of the river.
The river displays different characteristics at
each section.
2

3. River Structure
3

4. Upper valley characteristics
“V”shape valley,
mostly vertical
erosion
Interlocking spurs
Narrow, shallow
channel, low
velocity and
discharge
Large rocks
that come
from
upstream and
from valley
sides
4

5. Interlocking spurs,
Robinson, Lake District
An upper
course valley
often has
interlocking
spurs, and
steep valley
sides
5

6. River load in upper course
Why are they rounded?
6

7. River load in upper course
Why are they rounded?
Boulders are large and semi-rounded,
due to attrition within the load and
abrasion with the stream bed and
banks
7

8. Waterfall formation
Look at the diagram, How is a waterfall formed?
8

9. Upper Course: Waterfalls &
Gorges
Waterfall
and
Gorge 1
(OBLIQUE AERIAL
VIEW)
EROSION
TYPE: Vertical
and Headward
9

10. High Force waterfall, R. Tees
Waterfall
creates gorge as
it recedes
upstream by
eroding the base
and neck
Plunge pool
10

11. Upper Course: Potholes
Pothole
s
EROSION
TYPE:
Vertical
(by EDDY
CURRENTS)
Boulders broken off by erosion that sit on the river bed create
swirling eddy currents as the water flows past as the river is not
strong enough yet to move the boulders by TRACTION. These
eddies swirl the boulder round and erode a pothole in the river
bed by ABRASION.
11

12. Potholes, human scale!!
12

13. 13

14. Middle course, R. Tees
HOW DOES THIS DIFFER FROM
THE UPPER SECTION?
14

15. Middle course, R. Tees
Valley opens out,
more gentle
slopes, wider
valley bottom
First signs of
meanders
River channel
wider, deeper,
greater velocity
and discharge 15

16. Meandering Rivers
WHAT IS A MEANDER?
16

17. Middle Course: Meanders
Meanders
1
(Aerial View)
Meanders are formed
because the current
swings to the outside of a
bend and concentrates
the erosion there.
Deposition occurs on the
inside of the bed where
there is not enough
energy to carry load.
EROSION TYPE: Lateral

18. Middle Course: Meanders 2
Meanders
2
(Profile View /
Cross Section X - Y)
EROSION
TYPE: Lateral
This cross section clearly shows the eddy current (near ’X’) formed by
the velocity of the river being concentrated on the outside of the bend.
These UNDERCUT the bank causing the formation of a RIVER CLIFF. On
the inside (NEAR ‘Y’), a SLIP-OFF-SLOPE is formed where current is too
slow to carry any load.

19. Meander, R. Lavant,
Chichester
WHICH WAY IS THIS
MEANDER MOVING?
Slip-Off Slope
Pebble deposits on the inner meander bend
where there is low energy
Floodplain
River Cliff
19

20. WHERE IS EROSION
TAKING PLACE?
River Cliff
F
A
E
B
Slip-off
slope
C
}
Meander
loop
D
WHERE IS DEPOSTION TAKING
PLACE?
20

21. What happens to the river when it
moves to the middle course
Gradient becomes less steep
River continues to erode vertically a bit
but more LATERAL erosion now occurs in
MEANDERS
The meanders MIGRATE. What do you
think that means?
Name three effects it have on the
valley.
21

22. 22

23. Lower Course: Severn Valley
HOW DOES IT DIFFER FROM THE MIDDLE
COURSE?
23

24. Lower Severn Valley
Very wide
floodplain
Very gentle valley
side gradients
Well developed
meanders with
bars in the channel
indicating high
sediment load
24

25. Lower Course: Ox-bow lake
Ox-Bow Lake
1
(Aerial View)
EROSION TYPE: Lateral
Ox-bow lakes are formed
when
two
meander
RIVER CLIFFS are being
eroded
towards
each
other.
These
will
eventually meet, causing
the river to then flow
across the bottom of the
diagram.

26. Lower Course: Ox-bow lake 2
Ox-Bow Lake 2
(Aerial View)

27. Ox Bow lake on Mississippi
27

28. The Nile Delta from space
River Nile
28

29. Estuary Formation
HOW DOES THIS DIFFER FROM A
DELTA?
RAISED VALLEY SIDES
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