The document describes landforms created by erosion and deposition in the middle and lower courses of a river. In the middle course, meanders and oxbow lakes are formed. Meanders create point bars on the inside bend through deposition and river cliffs on the outside through erosion. Over time, meander necks may be cut off, forming oxbow lakes. In the lower course, levees and floodplains are formed. Levees are deposited along river banks during flooding, while floodplains are wide, flat areas deposited during over-bank flooding events.

2. Landforms of a River – Middle
and Lower
Lesson Objectives:
• Understanding how processes of erosion and deposition create landforms along a river
in its middle and lower course.

3. Middle Course landforms
• The main process in the middle course are
erosion and deposition

4. 1. Meanders and Oxbow Lakes
• Video here

5. • Meander on a map

9. RIVER CLIFF
POINT BAR
SLIP OFF SLOPE

10. Pont bar

11. Water is pushed to the outer bend . This
reduces friction with the bed and banks. So
the river has more energy for transporting
material which can erode the outside bank
via abrasion.
In the middle course lateral erosion
dominates as the river swings in large
bends known as meanders. Meanders
constantly change their shape and position.
What do you think happens on the inside of
the bend?

12. Point Bar
As the river loses energy
on the inside of the bend
(less water and more
friction) it also cannot
carry as much of its load
and so deposits it.
Deposited material builds
up on the slip off slope
and it forms a point bar.

14. Ox Bow Lakes

15. What happens next?

16. Ox bow lakes

20. 2. Features from erosion and deposition:
Oxbow Lakes
1. Meander formed through erosion and
deposition. A point bar develops on the
inside of the meander (due to deposition)
and a river cliff on the outside (due to
undercutting)
2. During periods of flooding the meander
neck is breached and the water takes the
fastest route across the meander.

21. 2. Features from erosion and
deposition: Oxbow Lakes
3. Erosion (Hydraulic action
especially) continues and the
neck is finally breached.
Deposition begins in the old
meander.
4. Deposition continues and
eventually a lake is formed that
is totally cut off from the river
channel – an oxbow lake.

22. 3. Landforms resulting from deposition in
the lower course: Levees & Floodplains

24. Levees

26. 3. Landforms resulting from
deposition: b. Levees
• Levees are _______ banks found along the side of a river in
its lower course.
• They form as a result of _________.
• The increase in _______ as the flooding river moves over
the land results in ______ it down. Therefore it has less
energy as it moves away from the channel.
• It then deposits its largest/heaviest material first along the
river ______ taking the finer/lighter material further over
the floodplain.
• Subsequent floods serve to ______ up the material along
the bank thereby creating levees.
bank flooding build friction
slowing raised

27. 3. Landforms resulting from
deposition: a. Floodplain
• Meanders widen the valley in the lower course by eroding
laterally as they move across it.
• In _________ conditions – water contained in the channel
• In flood conditions – Water floods onto the ____ land
adjacent to the river and ___________ material.
• _________ sediment is deposited first because the river lacks
energy. Then lighter sediment is carried ________ across the
flood plain as the ______ requires less _______ to move
lighter sediment.
• This creates a wide, flat area of land either side of the river
called the floodplain.
• Further Flat Heavier Normal
Deposits Energy River