1E Geography
Ms Cummins
Revision
1. Name and explain the different parts to a
river.
2. Name and explain the 3 different stages of a
river.
3. Name and explain the work of rivers.
Start on high,
Flow down low,
Creating features
As they flow!
River System
Youth Stage
=
Upper Course
Mature Stage
=
Middle Course
Old age Stage
=
Lower Course
The Work of Rivers
• The Work of Rivers includes:
1. River Erosion (wearing away the landscape).
2. River Transportation (removing the material
that it erodes).
3. River Deposition (Laying down or dropping
the material along the way or in the sea).
River Erosion
• Hydraulic Action
• Abrasion
• Attrition
• Solution
Transportation
Deposition
• The River drops or deposits its material when:
•
•
•
•
It loses speed and has less energy.
The river’s volume decreases.
It enters a flat or gently sloping plain.
When it flows into a lake or sea.
Learning outcomes
• You will know about the features that form at
a rivers Youthful Stage!
1. V-Shaped Valley
2. Interlocking Spurs
3. Waterfall and Plunge Pool.
The Youthful Stage
• The River has a steep gradient (slope).
• The Valley has a narrow floor and steep sides.
The Youthful Stage
• At the youthful stage rivers tend to be fast
flowing with lots of energy!
• Erosion is the dominating process at the
youthful stage
Features at a rivers Youthful Stage
• A number of features are created at a rivers
youthful stage!
• These are:
1. V Shaped Valley.
2. Interlocking Spurs.
3. Waterfall and Plunge Pool.
V Shaped Valley, example: River Liffey.
V Shaped Valley
• Description: A river valley with steep valley sides
and a narrow floor.
• Formation: In the youthful stage the steep
gradient results in a fast flowing river with lots of
energy. The river uses this energy to erode the
river bed. Vertical erosion dominates here.
Through abrasion and hydraulic action the river
erodes its bed to produce a valley with steep
sides and a narrow floor i.e. A V Shaped Valley.
• Leave space for diagram page 38 of book.
Interlocking Spurs, example: River
Liffey
Interlocking Spurs
• Description: are series of ridges that jut out from
both sides of a young river valley and lock into
one another like the teeth of a zip.
• Formation: when the river meets hard or
resistant rocks, it is unable to erode them.
Instead, it winds and bends to avoid them. The
rock land where the river has to make its way
around are called interlocking spurs.
• Leave space for diagram page 38 of book.
Waterfall and Plunge Pool e.g Torc
Waterfall, Kilarney, Co. Kerry
Waterfall
• Description: A sudden/sharp fall in the river bed.
• Formation: water falls from where there is hard
and soft rock side by side on the river bed. The
hard rock resists river erosion but the soft rock is
eroded by the river through abrasion and
hydraulic action. The river erodes the soft rock,
lowers the river bed and in time produces a
waterfall.
Plunge Pool
• Description: a pool at the bottom of a waterfall.
• Formation: when the river plunges over a
waterfall it “crashes” onto the river bed directly
beneath the waterfall. The impact of this on the
river bed cause hydraulic action to take place.
This causes erosion of the river bed which results
in a plunge pool directly beneath the waterfall.
• Leave space for diagram page 39 of book.
Can you put the
labels below into
the correct
place on he
diagram?
Features at a rivers Mature Stage
1. Meanders
2. U Shaped Valley
Meander example: River Strule,
Omagh
Meanders
Meanders
Description: Meanders are curves/bends that develop
along the mature (and old) course of a river.
Formation: Meanders are formed by a combination of
erosion and deposition. Erosion by abrasion and
hydraulic action on the outer bank is balanced by
deposition on the inner bank. It is erosion of the
outer bank and deposition on the inner bank which
results in a meander being formed.
The Old Age Stage
• The river flows much slower here.
• The river has an almost flat gradient.
• The valley has a wide flat floor and gentle
side.
Features at a rivers Old Age Stage
• Oxbow lake
• Levees
• Deltas
• Flood plains
Floodplain- Irish example- The River
Shannon, Shannon Bridge, Co. Offaly
• Description: level of land on either side of a mature (or
old) river that floods when a river overflows and is
covered with alluvium.
• Formation: rivers are sometimes not able to carry all of
the water in the river system. This might be the result
of heavy and persistent rain or winter snow and ice
melting. When the river can’t carry all of its water it
overflows. The flood waters carry sand, silt and
sediment with them this material is known as alluvium
material. When the floods are gone the alluvial
material left on the land make up a flood-plain.
Floodplain example, The River Tay,
Scotland.
Oxbow lake, example, River Liffey and
Mississippi
• Description : a meander which has been cut off from
the main river.
• Formation: erosion continues to take place on the
outer bank of the river and the neck of land between
the 2 meanders, as it gets narrower (diagram page 41
of book).
• During a flood when the river has more energy, the
neck of land is finally cut through. When this happens,
a new straighter river channel is created.
• Both ends of the meander are cut off from the river
channel to form an oxbow lake.
Levees
• Description : raised banks of alluvium that are
found along the banks of some rivers in their
old age stage.
• Formation: after many periods of flooding
over the floodplain deposits build up to form
levees.
• Example: River Moy and Liffey.
• Diagram page 41 of book.
Delta
• Description: lots of sand, silt and sediment built up
at the mouth of a river.
• Formation: Deltas are formed at the mouth of the
river. When a river flows into the sea it loses its
speed and deposits its material. If the material is a
large amount the tides and currents may not be
strong enough to take it out to sea. The deposits
build up gradually and eventually rise above sea
level to form a delta.
• Example, Po Delta- Northern Italy.
Stage
Slope
Main processes
Valley shape
Main features
Upper Course
Middle Course
Lower Course