The river from source to mouth
Over the period of the
next few lessons you
will understand how a
river changes from
source to mouth and
include this
information on the
diagram.
Predict…
How do you think the river will change as it
flows from source to mouth?
The upper course of a river
Aim: To understand what the
upper course of a river is like
A River's Upper Course (Youth)
Aim: To understand what the
upper course of a river is like
Processes of river erosion
Hydraulic action
Corrosion
Attrition
Abrasion
Definitions
Hydraulic Action
This process involves the force of water against the bed and banks.
Abrasion/Corrasion
This is the process by which the bed and banks are worn down by the river’s
load. The river throws these particles against the bed and banks, sometimes
at high velocity.
Attrition
Material (the load) carried by the river bump into each other and so are
smoothed and broken down into smaller particles.
Corrosion
This is the chemical action of river water. The acids in the water slowly
dissolve the bed and the banks.
Do you know your processes of erosion?
Watch the video of the upper
course of a river….
When complete you will be
undertaking the
following activities:
1. Describe the upper
course of the river?
2. What makes the upper
course of the river an
ideal place for the
source?
3. Complete paragraph
and fill in missing gaps.
Learning objectives
What are the main processes that operate
in the upper course?
What landforms occur in the upper
course of a river?
How are the landforms created?
Landforms in the upper course
V-shaped valleys and interlocking spurs
Rapids
Waterfalls
River Conwy
(near Mignant Moor)
river disappears from
view hidden by this spur
of land
Why do V-shaped valleys occur?
Interlocking spurs
In the upper course the river does not have a huge amount of energy to erode
as it does not have a high discharge and it has to transport large pieces of
sediment.
When the river meets areas of harder rock that are difficult to erode it winds
around them. A series of hills form on either side of the river called spurs. As
the river flows around these hills they become interlocked. So, a series of
interlocking spurs are often found in the upper course of a river valley.
Techniques! – 1. Fieldsketching….
Produce an annotated fieldsketch to show that this is part of an
upland river valley.
Waterfalls!
Seljalandsfoss, SW Iceland
Waterfall formation
Waterfalls
How does a waterfall form?
Rearrange the stages of formation into the correct order:
Waterfalls
Draw and annotate a diagram to explain the formation
of a waterfall.
Suggested labels:
1.
More resistant rock
2.
Less resistant rock
3.
Plunge Pool
4.
Unsupported rock
5.
Fallen rocks
6.
Gorge
Your labels should contain detailed explanations!
WATERFALL
RETREATS . .
UPSTREAM . .
OVERHANG
UNDERCUTTING
OF SOFT ROCK
PLUNGE
POOL
River load in upper course
Why are they rounded?
21
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
22
Finished questions?
Start your diagram completing the features
for the upper course of the river.