River processes
Learning objectives:
1.
Understand the different types of weathering
2. Know what mass movement is
3. Understand the different types of erosion and
transportation
4. Understand how material is deposited
Running water has a significant
influence on the development of
landforms.
Before we learn about these
landforms, we need to understand
the processes that shape them, as
well as the factors affecting these
processes:
1. Weathering and mass movement
2. Erosion
3. Deposition
What are the
differences between
these three rivers?
Why do differences
occur?
Activity
Copy and complete this paragraph…
Rivers are always at work changing and
shaping the surface of our world. When
rivers have lots of energy the water wears
away rock, stones and soil from their bed
and banks, this is called _____ . The rivers
then carry this material downstream, or
_____ it from one place to another. When
the river loses some of its energy it cannot
continue to carry the material so it drops it,
this is known as _____ .
Part 1 (a) What is weathering?
Weathering happens when
rocks are attacked and
broken up by the weather,
particularly through rainfall
and significant variations in
temperature.
There are 3 main types of
weathering:
1. Physical weathering
2. Biological weathering
3. Chemical weathering
10 mins
Your challenge...
• You will be working in groups and you will
receive some information on the following
topics to help you explain the processes that
happen in deserts:
• Physical weathering
• Chemical weathering
• Biological weathering
 Using the information you have, you need to
create a presentation with a maximum of 10
words – use picture representations that you
will then explain to your classmates
10 mins
Your next challenge
• One person will be the teacher
• The other people will go and find out
about one other process
• You will need to take notes as you will be
explaining it to the other members of
your group.
What is going on in this photograph?
A landslide –
this is a
hazardous
form of mass
movement.
Mass
movement
often initially
results from
weathering
because the
rock becomes
‘loose’.
15 mins
Part 1 (b) Mass movement in
river valleys
There are two main types of mass movement in river
valleys. Using the explanations below, draw an
annotated diagram to explain these two processes:
1. Slumping – this happens when the bottom of the valley
side is cut away by the river flowing at its base. This
makes the slope unstable and weathered material slopes
down towards the river. Slumping is also helped when the
weathered material on the slope is saturated by heavy
rain. The water makes the weathered material heavier
and also acts as a lubricant. Slumping of large amounts
of material often leads to a landslide.
2. Soil creep – when weathered material moves slowly down
a slope under the influence of gravity. It collects at the
bottom of the valley side and is eroded by the river.
20 mins
Part 2. What is erosion?
Erosion is the wearing away and removal of the land by
wind and water.
How much do you know
about erosion?
Using the next slide to
help you, try to
complete the first
section of the
worksheet
Processes of river erosion
Hydraulic action
Corrosion /
Solution
Attrition
Abrasion
Processes of River Erosion
Hydraulic Action
Abrasion
Attrition
Corrosion /
Solution
You are about to take part in the
secret art of erosion kung fu…
Hydraulic Action: make punching movements with handdemonstrates force of water hitting river bank.
Abrasion: make a throwing gesture with hands like you are
throwing dealing cards very rapidly
Attrition: make 2 fists, and then bring them towards each
other, hitting each other, then open hand to resemble a
stone breaking.
Corrosion: have arms out stretched in front of you, waving
fingers, and moving arms downwards. Sound effect of
something dissolving is needed.
How much do you know
about transportation?
Once the river contains
eroded material or any
type of ‘sediment load’,
it transports it
downstream.
Try to match the
correct terms with the
illustrations on the
diagram.
5 mins
Part 3. What is deposition?
Deposition: is the laying down of material
transported by the river – this occurs when
there is a decrease in energy, speed and
discharge of the river.
It often happens when the river enters a lake
or the sea, or wherever there is a decrease in
the gradient of the river’s channel
Odd one out
•
Saltation Traction Abrasion Suspension
•
Physical Mass movement Biological Chemical
•
Saltation Solution Attrition Hydraulic action
•
Steep gradient Low energy Decrease in discharge Low velocity
•
Slumping Deposition Weathering Mass movement
Odd one out - answers
•
Saltation Traction Abrasion Suspension
•
Physical Mass movement Biological Chemical
•
Saltation Solution Attrition Hydraulic action
•
Steep gradient Low energy Decrease in discharge
Low velocity
•
Slumping Deposition Weathering Mass movement