The Work of Rivers File

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Rivers
Chapter 7
Start on high,
Flow down low,
Creating features
As they flow!
Youth Stage
=
Upper Course
Mature Stage
=
Middle Course
Old age Stage
=
Lower Course
The Work of Rivers
Stage
Slope
Main processes
Valley shape
Main features
Upper Course
Middle Course
Lower Course
Stage
Slope
Main processes
Valley shape
Main features
Upper Course
Middle Course
Lower Course
The Work of Rivers
Processes of erosion:
1. Hydraulic Action
The force of the moving water causes
erosion of the river bed and the banks of
the river. The greater the speed and
amount of water the greater the force.
The Work of Rivers
Processes of erosion:
2. Abrasion
The rivers load is bounced and dragged
along the river bed causing it to scrape and
deepen the course of the river.
The Work of Rivers
Processes of erosion:
3. Attrition
The rivers load is constantly colliding in
the moving river water causing the load to
break down into smaller pieces.
The Work of Rivers
Processes of erosion:
4. Cavitation
As a river flows over the uneven river bed
air bubbles travel up to the top of the river,
pop and send ripples out towards the river
banks. These ripples gently erode the
rivers banks.
The Work of Rivers
Processes of erosion:
5. Solution
Chemicals in the rivers water and rocks
along the river course change the river
chemically which reacts with and erodes
various rocks along the way.
F.E.E.D
F: Feature (Name, erosion or deposition, stage it is found)
E: Explain with at least one or two processes explained
E: Three examples, one Irish
D: Clear 1/2/3 diagram/s to show how the feature is
formed.
Youth Stage
=
Waterfalls
Mature Stage
=
Meanders and Oxbow Lakes
Old age Stage
=
Deltas
• V – Shaped Valleys
• Interlocking Spurs
• Waterfalls
A typical upper course V-Shaped valley
with interlocking spurs, steep valley
sides and active slope processes.
The diagram below shows the formation
of interlocking spurs.
1
2
3
4
Waterfall
Youth Stage
Hydraulic Action
Abrasion
Waterfalls are features of erosion usually found in the upper course (youth stage) of a river.
They are found in areas where a river is flowing over bands of hard and soft rock. The
hard rock is slower to break down but the river can erode the soft rock much quicker. A
band of hard rock lies on an area of soft rock. The river erodes the soft rock by the
processes of hydraulic action (the force of the moving water) and abrasion (the scraping
of the rivers load against the banks and bed). This causes a small notch to be formed into
the soft rock which is eroded further into a drop over which the water falls. As the water
falls over the drop there is a greater rate of hydraulic action and the rivers load also scrapes
and deepens a hole in the bottom of the waterfall. This hole is called a Plunge Pool. The
hard rock is slowly eroded and hangs over the edge called a Overhang. This is eventually
worn down by the river and is carried away as the rivers load.
Examples of waterfalls include:
1
2
3
Diagram of a waterfall being formed
foe/sor
(e) px2
weu
Aoh/sr
srw
ucipp
neisr
[email protected]w
rfovd
Weu=
Waterfall
erodes
upstream
foe/sor=
Feature of erosion….stage of river
Aoh/sr srw=
Areas of
hard/soft rock,
soft rock weaker
Ucipp=
Undercut
collapses
into
plunge
pool
[email protected]=
Plunge pool
at base of
waterfall
(e) px2=
Erosion, Process
are hydrualic
action and
abrasion
Rfovd=
River falls over vertical
drop
Neisr=
Notch eroded in
soft rock
Can you put
the labels
below into
the correct
place on he
diagram?
Meanders and Ox Bow Lakes
Mature and Old Age Stage
Erosion and
Depositon
Ox Bow lake on Mississippi
F.E.E.D
F: Feature (Name, erosion or deposition, stage it is found)
E: Explain with at least one or two processes explained
E: Three examples, one Irish
D: Clear 1/2/3 diagram/s to show how the feature is
formed.
F.E.E.D
F: Feature (Name, erosion or deposition, stage it is found)
E: Explain with at least one or two processes explained
E: Three examples, one Irish
D: Clear 1/2/3 diagram/s to show how the feature is
formed.
Examples of deltas include:
The River Nile, Egypt
The Mississippi River in Louisiana, USA
The River Shannon in Limerick, Ireland
1. Name the river and the city of this case study?
2. The city is between two physical areas…what are
they?
3. How is the city protected from flooding?
4. What did the President do to the amount of money
available for protection of the land?
5. When did the disaster strike?
6. What was the name of the hurricane?
7. How many poor people could not leave the area?
8. How many people drowned in this disaster?
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